Viva in
Medical Physiology
Viva in
Medical Physiology
Second Edition
AK Basak
PhD
Professor and Head
Department of Physiology
Haldia Institute of Dental Sciences and Research,
Haldia, Purba Medinipur, West Bengal, India
Formerly
Associate Professor and Head
Department of Physiology
Institute of Dental Sciences , Bareilly, UP, India
Associate Professor and Head
Department of Physiology
Avadh Institute of Dental Sciences, Lucknow, UP, India
Asst. Professor in Physiology
Universal College of Medical Sciences, Nepal
Asst. Professor in Physiology
Nepalgunj Medical College, Nepal
®
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Viva in Medical Physiology
© 2009, Jaypee Brothers Medical Publishers
All rights reserved. No part of this publication should be reproduced, stored in a retrieval system, or transmitted in
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First Edition: 2004
Second Edition: 2009
ISBN 978-81-8448-684-1
Typeset at JPBMP typesetting unit
Printed at
To
my dear son
'Sohom’,
my students
and
well wishers
Preface to the Second Edition
I must extend my heart-felt gratitude for warm response from my
students, readers and colleagues and even my teachers for the 1st
edition of this book. I also acknowledge some suggestions from my
students and colleagues that led me to bring this 2nd edition of this
book. To make this book more beneficial and meaningful from the
examination point of view and also to make it self-contained as per
the demand of the students, the following aspects are also included
in this edition of this book:
 More number of clinical/applied questions with their answers.
 Questions with answers for preparing practical (Lab-based)
viva examinations.
 Important values to remember to have a bird's eye view on
different physiological norms just before facing the viva voce
examinations.
I am deeply indebted to Prof BN Koley and Dr (Mrs)
J Koley (Calcutta University), Prof NK Mishra and Prof SN Pandeya
(Nepalgunj Medical College), Prof V Reghunandanan and Dr (Mrs)
R Reghunandanan (Universal College of Medical Sciences), Prof VK
Negi (Harsaran Dass Institute of Dental Sciences, Ghaziabad), Prof
SK Saxena (Sikkim-Manipal Institute of Medical Sciences), Dr Ashoke
Agarwal and Dr Keshav Agarwal (Institute of Dental Sciences,
Bareilly, UP), Prof Sekhar Chakraborty and Dr J Samanta (Haldia
Institute of Dental Sciences and Research) who always thought very
good of mine. The generous help rendered by the faculty members
of Haldia Institute of Dental Sciences and Research (especially Dr
Soudeep Sau and Dr SR Tripathy) is also warmly acknowledged.
I also wish to express my sincere thanks to my wife Dhriti
Basak—who has helped me in each and every step of the
preparation of this book and also has edited the literary aspect
of this book.
Finally I also express my sincere gratitude to Shri Jitendar
P Vij Chairman and Managing Director, Tarun Duneja, DirectorPublishing and other Staff of M/s Jaypee Brothers Medical
Publishers (P) Ltd. for publishing this book.
viii VIVA IN MEDICAL PHYSIOLOGY
I will be grateful if this book meets the demand of the students.
The author is highly regretted for any typographical mistake,
human errors, inaccuracies or ambiguities if any in this title. I
will be very happy to receive any opinion, feedback and valuable
suggestions from the teachers, senior colleagues and students for
further improvement of this book.
AK Basak
Preface to the First Edition
While examining the MBBS and BDS students in their viva voce
examination, I have felt that even the good students hardly answer
the questions very precisely and to the point. Though there are small
number of viva books in Physiology with us, these are not sufficient
to meet the demand of the students so that they can answer A to Z of
viva questions generally asked by the examiners. Moreover, it is never
possible to the students to go through any text book while going to face
viva-voce examinations. These facts led me to write the book Viva in
Medical Physiology . While writing thisbook I have tried my best to
include all types of viva questions dealt with basic, brainstorming,
applied and clinical. Language of the book has also been kept easily
understandable. I hope this book will serve the purpose for not only
the BDS students but equally also the MBBS , MSc and BSc (Medical/
Human Physiology), MD (Physiology) students and also other allied
health subjects like physiotherapy, nursing, etc.
I am highly grateful to my students, colleagues and well wishers
of Avadh Institute of Dental Sciences (Lucknow); Universal College
of Medical Sciences (Nepal) and also Nepalgunj Medical College
(Nepal) for their encouragement and sincere suggestions for writing
up of this book. I am also deeply indebted to Prof. B N Koley and
Dr (Mrs) J Koley (Calcutta University), Prof NK Mishra and Prof SN
Pandeya (Nepalgunj Medical College), Prof V Reghunandanan and
Dr (Mrs) R Reghunandanan (Universal College of Medical Sciences),
Prof VK Negi (Harsaran Dass Institute of Dental Sciences, Gaziabad),
Prof SK Saxena (Sikkim-Manipal Institute of Medical Sciences),
Dr Rajuma Baudha (Avadh Institute of Dental Sciences) who always
thought very good of mine. I am also highly grateful to my family
members who always supported me in my academic pursuit.
I am really obliged to my wife, Mrs Dhriti Basak not only for
editing the language of this book but also for her sacrifice whose time
I usurped during the preparation of this book.
Finally I also express my sincere gratitude to Shri Jitendar P Vij,
Chairman and Managing Director, Tarun Duneja, Director-
x VIVA IN MEDICAL PHYSIOLOGY
Publishing and other Staff of M/s Jaypee Brothers Medical
Publishers (P) Ltd. for publishing this book.
I will be grateful if this book meets the demand of the students. I
will be very happy to receive opinions , comments and valuable
suggestions from all my senior colleagues, fellow teachers and
students so that every aspects of this book can be reviewed in
succeeding editions.
AK Basak
Contents
Section I: Theory Viva
1. Basic Concepts ................................................................... 1
2. Blood ................................................................................. 11
3. Cardiovascular System ................................................... 39
4. GI System and Metabolism ............................................ 75
5. Respiratory System ......................................................... 91
6. Nerve Muscle Physiology ............................................ 117
7. Excretory System ........................................................... 135
8. Skin and Body Temperature Regulation ................... 147
9. Central Nervous System .............................................. 152
10. Special Senses ................................................................. 178
11. Endocrinal System ......................................................... 189
12. Reproductive System .................................................... 212
Section II: Practical Viva
Part A: Hematology ...................................................... 226
Part B: Human Experiments ........................................ 239
Section III: Appendix
Important Values to Remember .................................. 252
BASIC CONCEPTS 1
SECTION I : THEORY VIVA
SECTION I: THEORY VIVA
1.1
Basic Concepts
1. What do you mean by unit membrane?
Not only the cell membrane but also the nucleus,
chloroplast and mitochondria are double membranous,
i.e. they are covered by two wall layers each of which, is
consisting of protein-lipid-lipid-protein. This type of
membrane is known as unit membrane.
1
2. What is fluid mosaic model of cell membrane?
As per this model all membranes of different cell
organelles along with the plasma membrane are made
up of double layer of lipid molecules in which proteins
are embedded like the tiles of mosaic floors. This model
is first proposed by Singer and Nicholson.
3. Mention the chemical nature of proteins present
in plasma membrane with special reference to its
functions.
Chemically the proteins present on plasma membrane
are of two types:
i. Lipoproteins—It functions as enzymes and ion
channels.
ii. Glyco-proteins—It functions as receptor for
hormone and neurotransmitters.
4. Classify the proteins as per their location on plasma
membrane and mention each of their functions.
As per their location proteins are of 3 types:
2 VIVA IN MEDICAL PHYSIOLOGY
i. Intrinsic protein—These are located in the inner
surface of membrane and serve mainly as enzymes.
ii. Extrinsic protein—These are located in the outer
surface of membrane and contribute to the
cytoskeleton.
iii. Transmembrane protein—They extend through the
membrane and serve as channel proteins, carriers,
pump and receptors.
5. Mention the function of SER and RER.
Functions of smooth endoplasmic reticulum (SER) are
as follows:
• It is the site of steroid synthesis.
• It plays important role in skeletal and cardiac muscles.
Function of RER: It is the site of protein synthesis.
6. Name at least four lysosymes.
These are: Ribonuclease and deoxyribonuclease,
phosphatase, collagenase and glycosidase.
7. What are the differences between microfilaments
and microtubules?
Microtubules are long, hollow structure, 25 mm in diameter
whereas microfilaments are solid fibres of 4-6 mm in
diameter.
8. Enumerate different types of cell junction and each
of their function.
On the basis of their functions cell junctions are classified
into 3 groups:
1. Occluding junction or Zona occludens or tight
junction—Prevents movement of ions and other
molecules across the membrane.
2. Anchoring junctions—These are of 3 types:
a. Macula adherens or desmosome—which acts as
a strong anchor between the cells/tissues is
subjected to mechanical stress like epidermis of
skin.
b. Zonula adherens or belt desmosome.
c. Fascia adherens or strip desmosome.
SECTION I : THEORY VIVA
BASIC CONCEPTS 3
3. Communicating junctions—These are again of 3 types
a. Gap junction- allows the speedy movement of Na+,
K+, Ca+2, ATP, Sugar, amino acids, vitamins, etc.
across the membrane.
b. Plasmodesmata.
c. Chemical synapse.
9. What are the types of intercellular communication?
There are 5 types of intercellular communication process
as follows:
i. Neural communication: In this process on
stimulation the nerve cells release neurotransmitters which act on post synaptic cell to activate
or inhibit it.
ii. Endocrine communication: In this process the
cells (endocrine cells) release hormones which
reach target cell via circulating blood and thus
communicate with other cells.
iii. Paracrine communication: Depending on the
requirement sometimes cell produces some
substances which diffuse to ECF. While circulating
through the ECF these substances control the
activity of neighbouring cells.
iv. Autocrine communication: Sometimes some cells
secrete chemical messengers which bind to
receptors on the same cell to modify the activity of
that cell. This process is known as autocrine
communication.
v. Juxtacrine communication: In some situations
some cells express multiple growth factors e.g.:
trans forming growth factors alpha (TGF α)
extracellularly on transmembrane proteins that
provide an anchor to the cell. Other cells having
TGF α receptors bind to those cells having TGF
α on their membrane to communicate each other.
4 VIVA IN MEDICAL PHYSIOLOGY
10. How does lipid and water soluble substances
diffuse through cell membrane?
Lipid soluble substances diffuse through lipid layer of
membrane whereas water soluble substances diffuse
through the channels present in cell membrane.
11. What do you mean by voltage gated and ligand
gated channels? Give example of each.
The ion channels, the gate(s) of which open or close by
alteration in membrane potential, is known as voltage
gated channels. Examples, Na+ and K+ or Ca++ channels
present in cell membrane.
Whereas the ion channels, the gate(s) of which open
or close in response to binding of channel proteins with
some ligand molecules like neurotransmitters, hormone,
intra-cellular Ca++, cAMP, G protein, etc. is called as ligand
gated channels. Example—Na+ and K+channels present
in post-synaptic membrane of synapses.
12. Name the types of bone cells. What is the function
of osteoclast cells?
There are three types of bone cells—Osteoblast,
Osteoclasts and Osteocytes. The osteoclast cells are
phagocytic in nature which digest the bone and release
their products into ECF.
13. Classify the bones and give the examples of each
of them.
On the basis of histology: It is of 2 types:
i) Compact bone: These are solid, dense and harder
(e.g. shaft of long bones)
ii) Cancellous (spongy) Bone: It is characterised by
bigger marrow spaces and is relatively less hard
(e.g. ends of long bones).
On the basis of shape: It is of 4 types:
iii) Long bones (e.g. femur, humorous)
iv) Short bones (e.g. carpals, tarsal, phalanges)
v) Flat bones (e.g. scapulae, sternum)
vi) Irregular bones (e.g. vertebral, facial bones).
SECTION I : THEORY VIVA
BASIC CONCEPTS 5
14. What is facilitated diffusion? Give example.
It is a carrier mediated transport process in which carrier
protein undergoes repetitive spontaneous configurational
changes during which the binding site for the substance
is alternatively exposed to the ECF and ICF and thereby
allow the inward movement of substances inside the cell.
Example—transport of glucose into RBC.
15. Name the factors affecting diffusion.
The factors are: Gradient, Temperature, Size of the
molecule, Solubility and Cross sectional area.
16. Define osmosis.
It is the passive flow of solvent, i.e. water across the
selectively permeable membrane into a region of higher
concentration of solute to which the membrane is
impermeable.
17. Define osmotic pressure.
The tendency for movement of solvent molecules to a
region of greater solute concentration can be prevented
by applying pressure to the more concentrated solution.
The pressure necessary to prevent this type of solvent
migration is called as osmotic pressure.
18. What is osmolarity and osmolality?
Osmolarity is the number of osmoles per litre of solution.
Whereas osmolality is the number of osmoles per kg of
the solvent.
19. What is osmolality of normal human plasma? What
is tonicity?
Osmolality of normal human plasma is 290 mosm/lit. The
osmolality of a solution relative to plasma is called as
tonicity.
20. How does hyperosmolality can produce coma?
It is by causing cellular dehydration.
6 VIVA IN MEDICAL PHYSIOLOGY
21. What is solvent drag?
When water flows into or out of capillaries it carries
dissolved particles with it. This force is known as solvent
drag.
22. Define active transport process. What are their
types?
When the transport of substances across the membrane
takes place against their chemical or electrical or pressure
gradient for which energy is required, this type of transport
process is called as active transport process. It is mainly
of 2 types as follows:
• Primary active transport where energy is required
directly.
• Secondary active transport in which the required
energy is obtained from primary active transport.
23. Name the types of pump required for primary active
transport with its site of location.
• Na+–K+ pump—Present in cell membrane of all parts
of the body.
• Ca+2–pump—Present in sarcoplasmic reticulum of
muscle cells.
• K +–H + pump—Present in the cells of the gastric
mucosa and renal tubules.
24. How many types of carrier mediated transport
processes are present in body? Name them with
examples?
These are of three types which are as follows:
• Uniport—facilitated diffusion of glucose in renal
tubules.
• Symport—secondary active transport of glucose in
renal tubules coupled with Na+.
• Antiport—Na+– Ca++exchanger in muscle cell and also
Na+– H+exchanger in renal tubules.
25. Define phagocytosis.
It is the process by which the extracellular substances
SECTION I : THEORY VIVA
BASIC CONCEPTS 7
like bacteria, dead tissue, foreign particles are engulfed
and digested by the cells.
26. What is the total amount of water in our body?
It is 42 litre in a 60 kg body weight person, i.e. 70 per
cent of the body weight.
27. Why total body water is lower in female than male?
It is because of presence of relatively greater amount of
subcutaneous fat in female body.
28. Name different compartments of ECF.
• Plasma—25 per cent
• Interstitial fluid—75 per cent
• Transcellular fluid—minute amount.
29. Name the method for measuring body fluid volume.
It is indicator dilution method.
30. What are the criteria of good indicator used for
measuring body fluid volume?
These are as follows:
• Must be non-toxic.
• Must mix evenly throughout the compartments being
measured.
• It should neither be reabsorbed nor be secreted.
• It should not alter the water distribution of the
compartment being measured.
• It should be relatively easy to measure.
31. From the clinical point of view define acidosis and
alkalosis.
Decrease blood pH, less than 7.35 is known as acidosis
and increase blood pH, more than 7.45 is called alkalosis.
32. What is buffer? What is its chemical nature?
Buffer is a substance that has the ability to bind or release
H+ ion in solution. Chemically it is a weak acid and its
conjugated base.
8 VIVA IN MEDICAL PHYSIOLOGY
33. What is anion gap?
There is a difference of sum totals of anions and cations
in each compartment which is known as anion gap.
Normal anion gap in plasma is 10-15 mosml/ lit which is
reduced in metabolic acidosis during diabetic coma.
34. Define oedema.
Accumulation of water either in cell interior (intra cellular
edema) or within ECF (extra cellular edema) is termed
as oedema.
35. What are the mechanisms by which body fluid
volume is regulated ?
The body fluid volume is kept constant within the normal
range by different mechanisms as follows:
1. ADH mechanism
2. By initiation of thirst sensation
3. By renin angiotensin–Aldosterone system
4. Renal body fluid mechanism
5. By controlling secretion of atrial natriuretic peptide
(ANP).
36. Define homeostasis.
Maintenance of the constant internal environment of the
body to enable its normal function is known as
homeostasis.
37. What do you mean by internal environment?
The ECF surrounding the body cells is called internal
environment as the cellular function depends on this
particular environmental condition.
38. What is negative feedback mechanism?
The homeostatic mechanism in which the final response
becomes opposite to that of its initiating stimulus is known
as negative feedback mechanism.
39. Define positive feedback mechanism.
The homeostatic mechanism in which the final response
becomes similar to that of its initiating stimulus is known
as positive feedback mechanism.
SECTION I : THEORY VIVA
BASIC CONCEPTS 9
40. Does the positive feedback is harmful to the body?
Not always, in case of parturition, blood clotting and
initiation of action potential positive feedback mechanism
is operated which is not harmful to the body rather
beneficial one.
41. Define action potential. What are its phases?
Definition: In response to a stimulus of threshold intensity
there is transient change in potential difference across
the cell membrane (inside electronegative and outside
electropositive) which when reaches to a critical level,
produces a electrical signal that can be propagated
beyond its site of origin. This transient change of
membrane potential which is propagatory in nature is
known as Action Potential (AP).
The phase of AP are—Resting or polarised phase,
depolarisation, repolarisation and hyperpolarisation.
42. What are monophasic and biphasic action
potential? Give the example of each of them.
The AP initiated in response to the stimulus can be
recorded through Cathode Ray Oscilloscope by placing
two electrodes in two separate site of the membrane. If
one electrode is placed outside the membrane and
another is inserted inside the membrane or one electrode
is placed externally on the surface of the healthy site of
the membrane and another at the damaged/injured/
sectioned site then the recorded action potential will be
monophasic.
Whereas if both the electrodes are placed at the
outside of the membrane the AP is recorded as an upward
deflection followed by short isoelectric period and then a
downward deflection which is known as biphasic action
potentia (Fig.1.1.1A).
Monophasic AP is intracellular recording whereas
biphasic AP is extracellular recordings.The examples of
biphasic AP are: ECG, EEG, EMG
10 VIVA IN MEDICAL PHYSIOLOGY
Fig. 1.1.1A: Graphical presentation of biphasic action potential
Fig. 1.1.1B: Graphical presentation of compound action potential
43. What is compound action potential?
It is the monophasic recording of the action potential from
the nerve trunk (mixed nerve) which contains many fibers
of varying diameter. As the diameter of the nerves fiber
in a mixed nerve varies their conduction rate will also
vary. This is why the onset of the peak in different nerve
fiber will be different resulting a wavy action potential
(Fig. 1.1.1B).
BLOOD 11
SECTION I : THEORY VIVA
1.2
Blood
1. What are the formed elements of blood?
These are RBC, WBC and platelets.
2. Enumerate the functions of plasma protein.
These are:
A. Coagulation of blood: Fibrinogen, prothrombin and
other coagulation factors help in coagulation of blood.
B. Maintenance of colloidal osmotic pressure: The
plasma proteins do not pass through the capillary
membrane easily during normal state. So it remains
in the blood and exerts osmotic pressure. This helps
to maintain the exchange of fluid at tissue level.
C. Maintenance of viscosity of blood and Blood
pressure: It (especially albumin) regulates viscosity
of the blood and as resistance of blood flow is directly
proportional to viscosity of blood, it also maintains the
systemic arterial blood pressure.
D. Maintenance of acid base balance: The plasma
proteins, particularly albumin, play an important role
in maintaining the acid base balance in the blood.
This is due to the fact that in physiological pH plasma
proteins exist as an ‘ionised’ form and in this form it’s
C terminal end (i.e. COO= –) can buffer the change
due to the addition of an acid and N terminal end (i.e.
–NH3+) can buffer the change that follow addition of
an alkali.
E. Regulation of ESR : Globulin and fibrinogen increase
the rate of rouleaux formation and thus increase ESR.
12 VIVA
IN MEDICAL PHYSIOLOGY
F. Providing of suspension stability of RBC: During
circulation, the RBCs remain suspended uniformly in
the blood without rouleaux formation. This property
of RBC is known as suspension stability of RBC,
which is provided mainly by globulin and fibrinogen.
G. Act as a reservoir : Plasma proteins act as a reservoir
during the conditions like fasting, starvation, etc.
H. Production of trephone: Leukocytes produce
trephones from plasma proteins which are required
for nourishment of tissue cells in culture.
I. Immune function: Globulin produces antibodies and
thus provides immunity to the body.
J. Transportation: It combines loosely with hormones,
metal, drugs, etc. and transports to appropriate site
for their release as an active components.
K. Fibrinolysis: Intravascular clot (thrombus) is digested
by the enzymes of fibrinolytic system present in plasma
which saves the body from disastrous effects of
thrombus.
3. What are the non-protein substances in blood?
These include urea, uric acid, creatine, creatinine,
xanthine and hypoxanthine (in traces).
4. Name three clinical conditions when NPN in blood
alters.
NPN increases in renal insufficiency, adrenal insufficiency
and thyrotoxicosis, whereas it decreases in later months
of pregnancy.
5. What are non-NPN substances in blood?
These are neutral fat, phospholipids, glucose and
cholesterol.
6. What is the difference between plasma and serum?
Plasma is fluid portion of the blood obtained without
clotting while serum is the fluid obtained after clotting.
Serum is thus plasma without fibrin.
SECTION I : THEORY VIVA
BLOOD 13
7. What is the normal concentration of plasma
protein?
It is 6.4-8.3 gm/100 ml of blood.
8. What is the origin of plasma proteins?
• In embryonic stage—Mesenchymal cell
• In adult—Albumin and fibrinogen from liver; globulin
from reticulo-endothelial cells, lymphocytes.
9. What will happen if plasma protein concentration
decreases?
a. Less than 2 gm%: results shock and even death.
b. To 4 gm%: exhaustion of protein reserves in the
body
10. How hypoproteinemia produces edema?
Hypoproteinemia→ decrease in capillary oncotic
pressure→ decrease in filtration at arterial end→
decrease in absorption of fluid at venous end→
abonormal collection of fluid in interstitial spaces→
edema.
11. What is A/G ratio?
It is the ratio of albumin to globulin. Normally it is 1.7:1.
12. Name three conditions when there
physiological decrease of albumin.
In infancy, newborns and early pregnancy.
is
a
13. What is the average daily production of plasma
proteins?
It is about 15 gm/day.
14. Can any of the plasma proteins pass through
capillary endothelium?
Capillary endothelium normally is impermeable to plasma
proteins though in some diseases like glomerulonephritis,
nephrotic syndrome, etc. albumin can pass through the
capillary membranes.
14 VIVA
IN MEDICAL PHYSIOLOGY
15. State the specific gravity of blood, serum and
corpuscles.
Blood: 1.055–1.060; Serum: 1.028–1.032; Corpuscles:
1.090.
16. Name the main conditions in which blood viscosity
rise.
It is during acidosis, hypercalcaemia and
hyperglycaemia.
17. What is the normal pH of blood?
It is 7.3 - 7.4.
18. Name the buffer systems in the body which help to
maintain the body pH.
It is bicarbonate, phosphate, protein and hemoglobin
buffer systems.
19. How is the biconcavity of RBC is maintained?
It is maintained by the presence of a contractile layer of
a lipoprotein molecule "spectrin" in a fibrillar manner below
its cell membrane.
20. What are the advantages of biconcave shape of
RBC?
These are:
• It can withstand considerable changes of osmotic
pressure by altering its cell volume and thereby
prevent hemolysis.
• Allows easy passage of RBC through narrow
capillaries by folding itself.
• Facilitates quick and optimal exchange of gases in
and out of hemoglobin.
21. What are the advantages of having no nucleus, no
mitochondria and no ribosome in RBC.
It is to accommodate more amount of hemoglobin and
also to decrease the use of O2 by its own structure and
thereby increases the availability of O2 to the other cells.
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22. What are the disadvantages of non-nucleated RBC?
• It cannot multiply.
• It cannot synthesize necessary enzymes so has less
life span.
23. How does RBC survive for 120 days though it has
no nucleus, mitochondria and ribosomes?
For energy supply RBCs depend on glucose metabolism
only, which comes through facilitated diffusion. These
glucoses are oxidised by cytoplasmic enzymes already
present inside the cells to get the energy for their activity.
When these cytoplasmic enzymes are exhausted, i.e.
after 120 days, it dies.
24. Which is the principle cation in RBC?
It is potassium ion.
25. What is the diameter of normal RBC?
It is 6.7-7.7 cµ.
26. Why RBC is stained pink by Leishman’s stain though
it has no ribosomes in their cytoplasm?
It is because of presence of hemoglobin.
27. Mention the site of RBC formation.
• In foetus—bone marrow, spleen, liver and thymus
gland.
• After birth—red bone marrow of long bones like
sternum, vertebrae, etc.
28. Name the mother cell of RBC.
Haemocytoblast which gives rise proerythroblast.
29.
Why hemoglobin is present within RBC not in
plasma?
There are several reasons like:
• To prevent rise of viscosity of plasma that may lead
to increase of blood pressure.
• To prevent the increase in osmotic pressure of plasma
and thereby prevent the disturbances of fluid exchange
mechanism due to rise in osmotic pressure.
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To prevent breakdown of Hb by tissue macrophage
system.
To prevent loss of Hb through urine.
30. What is the shape of Hb crystals of human blood?
What is its name?
Shape is rhombic or trycyclic. It is haemin crystal.
31. What is the site of production of heme of Hb?
It is in mitochondria.
32. Mention the average daily production of Hb in the
body?
It is about 7-8 gms/day.
33. Name the common methods of Hb estimation.
These are:
Sahli’s haemoglobinometer method, Haldane
haemoglobinometer method, Oxy-Hb colorimetric and
also Cyano methaemoglobin colorimetric method.
34. Why does Sahli’s method so accurate?
• In this method reduced Hb in the blood is not
converted into acid haematin, thereby the value
obtained is less than the total Hb content in the blood.
• This method depends on person’s colour vision. As
the colour vision varies from person to person result
may also vary.
35. Enumerate main functions of iron.
These are: Hb synthesis, RBC development, O2 carriage
and tissue oxidation through cytochrome.
36. In which form iron is stored in reticuloendothelial
cells?
Ferritin and hemosiderin form.
37. Mention the forms of Hb present in human blood.
These are: Oxyhaemoglobin, carbaminohaemoglobin,
reduced (deoxygenated) Hb, Carboxy-Hb and
Methaemoglobin.
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38. Mention the varieties of haemoglobin with special
reference to difference of each.
These are as follows:
• Adult Hb (HbA) - Contains 2 α and 2 β globin chain.
• Adult Hb (HbA2) - Contains 2 α and 2 δ chain.
• Foetal Hb (HbF) - Contains 2 α and 2 γ chain
• HbS
- Contains 2 α and 2 β chain
but in β chain glutamate of 6th
position is replaced by a valine
residue.
39. Why does Hb level lower in female?
This is due to the:
• Presence of estrogen which inhibits erythropoietin
secretion resulting less RBC formation.
• Absence of testicular androgens which stimulate
Erythropoietin secretion in male and thereby
increases RBC count.
40. Why does Hb level high in the newborn?
The newborns are generally in a state of mild hypoxia
which in turn stimulates erythropoietin secretion and
thereby increases RBC count and thus Hb concentration.
41. What is the fate of hemoglobin?
Old and inactive red cells are ingested by the RES and
are broken into globin and iron. Globin and iron are
reused whereas the porphyrin moiety of iron is converted
into biliverdin and thence bilirubin which are excreted into
bile and ultimately excreted mostly through the faeces
and partly through the urine.
42. Define anaemia.
It is a clinical condition characterised by decrease in O2
carrying capacity of blood either due to decreased Hb
concentration or decreased RBC count or both.
43. Classify anemia.
On the basis of etiological classification it is of following
types:
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Hemorrhagic anemia
Dietary deficiency anemia like folic acid deficiency and
iron deficiency anemia.
Anemia due to abnormal hemopoiesis, i.e. aplastic
anemia.
Hemolytic anemia.
44. What are the signs and symptoms of anemia?
• Signs: Paleness of skin and mucous membrane of
mouth cavity, etc. spoon-shaped nails and
hemorrhages in the retina. In severe cases there may
be enlargement of heart and even heart failure.
• Symptoms: Breathlessness, fatigue, palpitation, loss
of appetite and bowel disturbances.
45. What is the commonest form of anemia in the world?
It is iron deficiency anemia.
46. What is the etiology of pernicious anemia?
It is due to deficiency of hematinic principle, i.e. lack of
castle’s intrinsic factor, resulting failure of absorption of
vitamin B12 from diet through ileum.
47. Name the physiological and pathological condition
of anemia?
Physiological—Pregnancy.
Pathological—Thalassemia, spherocytosis, malaria, iron
deficiency, etc.
48. What is polycythemia? What is its difference with
polycythemia vera?
Polycythemia refers to the increase in the number of RBC
above normal level. Polycythemia vera is the condition
characterised by very high RBC count due to gene
abnormalities of hemopoietic cells.
49. Name the physiological and pathological condition
of polycythemia.
Physiological—Muscular exercise, high altitude, high
environmental temperature, etc.
Pathological—Cardiac failure, diarrhoea, etc.
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50. Which is the most common site for bone marrow
biopsy?
Body of sternum between 2nd and 3rd ribs.
51. Which type of bone marrow is concerned with
hemopoiesis - red or yellow?
It is red bone marrow.
52. What are the common indications for bone marrow
study?
These are – disorders of haemopoietic system, conditions
like multiple myeloma, cancer in lung, liver, prostate,
breast, etc.
53. What is the normal average ratio of WBC to RBC in
human blood?
It is 1:700 (WBC:RBC).
54. What is MCV and what is its significance?
It is volume of a single RBC in cubic micron. The normal
range is 74-94 mm3. It is the basis to diagnose the maturity
of the RBC, i.e. whether it is normocytes or microcytes or
macrocytes.
55. What is MCH?
It is the average amount of Hb in a single RBC in
picogram. Normal value is 30 pgm (range:28-32 pgm).
56. What is MCHC? What is its importance?
It is the amount of Hb expressed as percentage of the
volume of a RBC or it is the Hb concentration in a single
RBC. Normal value is 33 per cent (range: 35 ± 3%). MCHC
is determined to know whether the RBC is normochromic
or hypochromic.
57. Can it be possible to be hyperchromic anaemia?
No, as MCHC can never be more than 38% because it
cannot hold Hb beyond the saturation point.
58. What will happen
a. If iron in heme is present in ferric form
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b. If HBF persists during adult life:
i. Ferric form of iron will bind O2 tightly resulting no
removal of O2 from iron atom and then O2 can not
be used by the body.
ii. If HBF is present in adult blood there is shifting of
O2 dissociation curve to the left because of less
affinity of HbF for 2-3-DPG resulting more uptake
of O2 in lungs and less release of O2 in tissues.
59. What will happen if folic acid is given to pernicious
anemic patient?
The administration of folic acid to pernicious anemic
patient will improve the blood picture but it can not protect
against neuropathy which is due to deficiency of vit-B12.
60. What is the role of iron in the body?
These are: synthesis of hemoglobin, myoglobin and
cytochromes.
61. What is the blood and bone marrow picture in iron
deficiency anemia?
The RBCs are microcytic, hypochromic and MCH, MCHC
and total RBC count is reduced, whereas the bone marrow
shows proliferation of the precursor cells with a larger
proportion of the mature forms. Some of the precursor
cells may show scanty, polychromatic cytoplasm with a
pyknotic necleus, i.e. the cytoplasmic maturity is less
than nuclear maturity.
62. What is the blood and bone marrow picture in
megaloblastic anemia?
The blood picture is characterised by macrocytosis,
anisocytosis, poikilocytosis, neutropenia with over
matured neutrophils and also thrombocytopenia.
Whereas in bone marrow all the RBC precursors show
megaloblastic changes that includes:
1. Larger cell with larger nucleus
2. More reticular chromatin
3. Normal hemoglobinisation of cytoplasm.
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63. What is the dietary, active and therapeutic form of
folic acid?
• Dietary form: polyglutamates
• Active form: tetrahydropholate
• Therapeutic form: pteroylglutamic acid
64. What are the effects of foliate deficiency?
This results defective erythropoiesis resulting
megaloblastic anemia.
65. Compare and contrast the folic acid, vit-B12 and iron
deficiency anemia.
Iron deficiency anemia
Folic acid deficiency
anemia
Vit-B12 deficiency
anemia
RBC s are microcytic and
hypochromic
RBC s are macrocytic
RBC s are macrocytic
Bone marrow shows
hyperplasia of red cell
precursors
Bone marrow shows
megaloblastic
changes and presence
of erythroblasts
Bone marrow shows
megaloblastic changes
and presence of
erythroblasts
Nuclear maturation of
RBC is normal
Nuclear maturation of
RBC is impaired
Nuclear maturation of RBC
is impaired.
No associated
neurological hazzards
No associated
neurological hazzards
Associated neurological
hazzards
66. Give characteristics features of (i) iron deficiency
anemia (ii) pernicious anemia.
i. Characteristics feature of iron deficiency anemia is
as follows:
• Microcytic hypochromic RBC
• MCV, MCH, MCHC and CI decreases
• RBC count decreases or remains normal
• Normoblastic hyperplasia of bone marrow
• Normal WBC and platelet count
• Soft, brittle and spoon shaped nail
• Angry red tongue and dysphagia
• Irritability, loss of concentration, headache,
impotence
• Early breathlessness, palpitation
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ii. Characteristics feature of pernicious anemia is as
follows:
• Microcytic normochromic RBC
• Marked decrease in RBC count and Hb
concentration
• Lemon yellow coloured skin due to anemic
paleness and mild jaundice
• MCV, MCH increases and MCHC remains normal
• Increase in reticulocyte count
• Low grade hemolytic jaundice
• Increase in serum iron concentration
• Paresthesia, i.e. numbness, tingling, burning
sensation ataxia, etc.
67. Define colour index.
It is the ratio of Hb to RBC which is normally about 1
(range 0.85-1.15).
68. What is PCV?
It is the percentage composition of the cells in the whole
blood.
69. What is ESR? How it differs from PCV?
ESR is the rate of settling of red cells in a special tube
fixed vertically. To determine PCV the tube containing
anticoagulant mixed blood is required to be centrifuged
whereas in ESR centrifugation is not required.
70. What is importance of ESR?
It helps to diagnose broader aspect of some disease
though it has got more prognostic value. It helps in
assessing the progress of patients treated for chronic
diseases like pulmonary tuberculosis and rheumatoid
arthritis.
71. What happens if the RBC is kept in hypotonic and
hypertonic saline?
• In hypotonic solution, water moves inside the RBC
cell due to concentration gradient → swelling up of
RBC →increase of RBC volume →rupture (hemolysis)
of RBC takes place.
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In hypertonic solution, water moves out of the cell →
shrinkage of the cell (crenated).
72. What is the clinical significance of doing osmotic
fragility test?
It is a screening test in various types of hemolytic anemia
and also used as a diagnostic purpose in hereditary
spherocytosis.
73. Enumerate the variations of osmotic fragility of RBC.
Osmotic fragility is decreased during acholuric jaundice
and some anemias. Whereas it is increased during
hereditary spherocytosis, deficiency of glucose-6phosphate dehydrogenase, cobra bite, etc.
74. At what serum bilirubin level clinical jaundice
occurs in adults and infants?
• In adult: If serum bilirubin increases beyond 2 mg% it
results jaundice
• In infants: If serum bilirubin increases beyond 5 mg%
it results jaundice
75. Why jaundice is first detected in the eyes?
It is because of whiteness of sclera. Sclera has a protein
known as elastin which has high affinity to bind bilirubin.
So even in low grade of jaundice bilirubin can get bind
with sclera.
76. What is the clinical importance of glycosylated
hemoglobin?
The blood level of glycosylated hemoglobin (HbA1C)
reflects the average blood glucose level over the period
of preceding 5-8 weeks and thus serves as an index of
long-term control of diabetes mellitus. Thus a pateint if
becomes careless about controlling his hyperglycemia
and takes an insulin injection only before visiting his
doctor would have normal blood glucose but his HbA1C
will be raised.
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77. Why does stool darken on standing in air?
It is due to the conversion of residual urobilinogens
(colourless) to coloured urobillins.
78. What is prehepatic jaundice? Why it does result in
unconjugated hyperbilirubinemia?
When jaundice occurs due to increased formation of
bilirubin it is called as prehepatic or hemolytic jaundice.
In this case the liver is unable to conjugate the large
amounts of bilirubin produced resulting in unconjugated
hyperbilirubinemia.
79. What is post hepatic jaundice? Why it does result
in conjugated hyperbilirubinemia?
If the jaundice occurs due to biliary obstruction it is known
as post hepatic jaundice. In this case the conjugated
bilirubin produced in the liver regurgitates back into blood
instead of flowing out into the duodenum. This is why it
results in conjugated hyperbilirubinemia.
80. What is hepatic jaundice? Why it does usually result
in conjugated hyperbilirubinemia?
The jaundice due to the impairment of all steps of bilirubin
metabolism in liver is known as hepatic jaundice. The
commenest cause is infective hepatitis. In this case the
excretion of bilirubin is worstly affected that results in
conjugated hyperbilirubinemia.
81. What are trephones?
These are the substances prepared by leucocytes from
plasma proteins that help in tissue nutrition.
82. What is the average period for normal development
of neutrophils?
12 days.
83. Why the neutrophils are called polymorphs?
Because they have multilobed nucleus.
84. Why neutrophils are so named?
This is a misnomer because they are not stained by the
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neutral stain rather by the mixed (both acidic and basic)
stain like Leishman stain.
85. Which stain is generally used to stain the peripheral
blood smear?
It is Leishman stain.
86. Which is the largest cell in the peripheral blood?
It is monocyte (diameter 15-20 µm).
87. What is respiratory burst?
Within seconds of stimulation neutrophils sharply increase
their oxygen uptake which is known as respiratory burst.
88. What is Cook-Arneth count? What is its
significance?
Counting of neutrophils on the basis of the number of
lobes of their nuclei is called Cook- Arneth count.
Clinical significance: It represents the maturity of
neutrophils. If shift to the left occurs that indicates the
hyperactive bone marrow whereas hypoactive bone
marrow is indicated by shift to the right.
89. How do you differentiate between neutrophils,
eosinophils and basophils?
Parameter
Neutrophils
Eosinophils
Basophils
1. Size of the cell
2. Number of lobes
in nucleus
10-14 µm.
10-16 µm
10-14 µm
Multilobed
Usually bi lobed
bi lobed
3. Shape of nucleus
Irregular
Spectacleshaped
Usually ‘S’ shaped
4. Colour of granules
in cytoplasm
Pinkish
Brick red
Purple
5. Nature of granules
Very fine
Coarse
Very coarse, making
the nucleus obscure
Very dense
Small in number
6. Number of granules
Few
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90. How do you differentiate small and large
lymphocyte? Which one is more mature?
Parameter
Small Lymphocyte
Large Lymphocyte
1. Size of the cell
Almost equal to the
RBC size
Almost twice of RBC
2. Amount of
cytoplasm
Very thin layer of
cytoplasm present
only in periphery
Plenty in compare to
small lymphocyte.
3. Shape of nucleus
Round
Round or oval
Small lymphocyte is more mature.
91. How do you differentiate large lymphocyte with
monocyte?
Parameter
Large lymphocyte Monocyte
1. Size
Twice of RBC
Almost thrice of RBC
2. Shape of nucleus
Round or oval
Indented or kidney-shaped
3. Position of nucleus
Central
Eccentric
4. Amount of cytoplasm
More than
half of the cell.
Less than
half of the cell
92. What is Schilling index?
Arranging and counting of all leucocytes according to
their age is known as Schilling index.
93. What are the body’s Ist line of defense and where
they are located?
It is monocyte macrophage system or RES. They are
located in almost all the tissues but in different form, e.g.:
• In skin and subcutaneous tissues — Histocytes
• Lungs
— Alveolar
macrophages
• Intestine
— Lymphoid tissue
• Liver and spleen pulp
— Kupffer cells.
94. Which lobed neutrophils are most active?
It is three lobed neutrophil (N3).
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95. What do you mean by shift to the left and what is its
significance?
In Arneth count, if N1 + N2 + N3 becomes greater than 80
percent then it is known as shift to left or regenerative
shift. It indicates the hyperactive bone marrow.
96. What is shift to the right? What is its significance?
In Arneth count, if N4 + N5 + N6 is greater then 20 per
cent it is called as shift to right or degenerative shift which
indicates the hypoactive bone marrow.
97. Is trilobed eosinophil possible?
Yes, 15 percent of eosinophils are trilobed.
98. What are the stages of phagocytosis of WBC?
These are as follows:
Diapedesis → chemotaxis → opsonisation and then
phagocytosis → which causes degranulation → then
inflammatory response → finally stops or limits
inflammation.
99. Classify the lymphocytes.
Histologically—two types: Small and large lymphocytes.
Functionally—two types: T-lymphocytes (responsible for
cellular immunity) and B-lymphocytes (responsible for
humoral immunity).
100. Define neutrophilia and neutropenia. Mention each
of their causes.
Increase in the number of neutrophils in differential count
and absolute count (over 10,000 cumm of blood) is called
as neutrophilia.
Causes
Pathological
• Acute pyogenic infection like abscess, tonsilitis,
appendicitis, etc.
• Burn, acute hemorrhage and hemolysis
• Tissue necrosis like myocardial infarction and renal
infarction.
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Physiological: Muscular exercise, stress, pregnancy, etc.
Neutropenia: The clinical condition characterised by the
reduction of neutrophil count in both differential and
absolute count is called as neutropenia.
Causes
• Viral infection like typhoid, paratyphoid, AIDS, Kalaazar, etc.
• Bone marrow depression.
101. Define eosinophilia and eosinopenia. Mention their
causes.
Increase of absolute eosinophil count more than 500 cells
per cumm of blood is called as eosinophilia whereas the
reduction of the absolute count below 50 cumm of blood
is known as eosinopenia.
Causes of eosinophilia—Allergy, parasitic infection,
leukaemia, etc.
Causes of eosinopenia—ACTH or glucocorticoid therapy,
acute stressful illness and acute pyogenic infection.
102. What is basophilia? When does it occur?
Increase of absolute count of basophil more than 100
cumm is known as basophilia. It occurs in viral infection
like small-pox, chickenpox and also in chronic myeloid
leukaemia.
103. What is monocytosis? Mention the causes of
monocytosis and monocytopenia.
Increase in the count of monocyte (absolute count >5000/
cumm of blood) is called as monocytosis.
Causes of monocytosis—Malaria, Kala-azar, Rheumatoid
arthritis, Leukaemias, etc.
Causes of monocytopenia—Bone marrow depression.
104. Define lymphocytosis and lymphopenia. When do
they occur?
High lymphocyte count (absolute count > 5000/cumm of
blood) is known as lymphocytosis. It occurs in viral
infection like chickenpox, whooping cough, etc., chronic
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infection like TB, hepatitis, leukaemia, etc. Whereas low
lymphocyte count in peripheral blood is known as
lymphocytopenia. It is seen in patients with steroid
therapy.
105. What is leukaemoid reaction?
Extreme increase of TLC (>50,000/cumm of blood)
characterised with elevated level of leucocyte alkaline
phosphatase due to severe infection is known as
leukaemoid reaction. Its difference with leukaemia is that
in case of leukaemia alkaline phosphatase level is
reduced whereas here it is increased significantly.
106. What is leucocytosis? Name the physiological and
pathological condition causing leucocytosis.
Increase in TLC beyond 11000 cells/cumm of blood is
called leucocytosis.
Physiological condition—Newborn babies, exercise,
parturition, etc.
Pathological condition—Acute pyogenic infection like
boils, abscess, tonsilitis, appendicitis and also MI, burns
and malignancies.
107. What is leukopenia? Name the physiological and
pathological conditions causing leukopenia.
Decrease of the TLC below 4000 cells/cumm of blood is
known as leukopenia.
Causes
Physiological condition — Exposure to extreme cold.
Pathological condition — Nonpyogenic infection like
typhoid, paratyphoid fever.
• Viral infection like influenzae, smallpox and AIDS.
• Arsenic and Antimony poisoning,
• Vit. B12 and folate deficiency.
• Malnutrition and starvation.
108. What is the leukaemia? What is its difference with
leukocytosis?
Leukaemia is a group of malignant neoplasms resulting
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from uncontrolled proliferation of hemopoietic leukocytic
stem cells of bone marrow and lymphoid tissue.
In this case, TLC becomes much higher than
leukocytosis, i.e. 1-3 lac/cumm and number of immature
cells are dominant.
109. Mention the functions of platelets.
These are to: protect endothelial linning of blood vessels,
initiate blood clotting, hasten clot retraction, release
histamine and prostaglandin for vasoconstriction.
110. What are the events involved in hemostasis?
These are:
a. Vasoconstriction
b. Formation of temporary hemostatic plug.
c. Conversion of temporary hemostatic plug into
secondary or definitive hemostatic plug by fibrin.
111. How the primary hemostatic plug is formed?
It is represented by the following sequences:
Platelets adhesion → platelets activation → platelets
aggregation →activation of phospholipase A2 →release
of arachidonic acid from membrane phospholipids →
release of thromboxane A2 and prostacyclin → this
ultimately causes adhesion of more and more platelets
and then platelets are aggregated with each other to seal
the rupture of blood vessels temporarily.
112. What are the principle causes of hemorrhagic state
in the body?
These are:
a. Defect in the blood vessels due to infection, allergy,
etc.
b. Defect in platelets (purpura)
c. Defect in clotting mechanism.
113. Which coagulation factor is lacking in hemophilia?
It is factor VIII or anti-hemophilic globulin.
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114. What is clot retraction? What is the role of platelets
in clot retraction?
After the formation of clot, it starts contracting and after
about 30-45 min, a straw coloured fluid, i.e. serum oozes
out. This process of contraction of clot and oozing of
serum out of clot is called as clot retraction.
The platelets contribute directly to clot retraction by
releasing the platelet thrombosthenin, actin and myosin
which causes strong contraction of the platelet spicules
attached to the fibrin.
115. Name some anticoagulants used in hematological
study.
These are: sodium citrate, potassium oxalate, amonium
oxalate, EDTA, etc.
116. Why blood do not clot in the body?
This is because of following reasons:
• Smoothness of endothelial lining which prevents
platelet adhesion.
• Negativity of endothelial lining that repels the
negatively charged plasma clotting factors.
• High blood pressure that increases velocity of blood.
• Presence of natural anticoagulants like heparin and
protein C in the blood.
• Simultaneous activation of fibrinolytic system along
with clotting mechanism. This causes lysis of fibrin
molecules.
117. What is the mode of action of heparin as an
anticoagulant?
It inhibits the reaction between thrombin and fibrinogen
and also interferes in formation of thromboplastin.
118. What is the importance of vit K in coagulation?
Vitamin K serves to maintain the plasma prothrombin
level.
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119. What is platelet ratio?
It is the ratio of platelets to RBC which is about 1:16 to
18.
120. Which one is the principal plasma protein
associated with rate of sedimentation of RBCs.?
It is fibrinogen.
121. What are indications of BT and CT?
These are:
a. Frequent and persistent bleeding from minor injuries.
b. Before the minor/ major surgeries.
c. In case of family history of bleeding.
122. Which aspects of hemostasis are tested by BT and
CT?
BT is to test for platelet function whereas CT is to test
the abnormalities (if any) in clot formation. That is why in
hemophilia BT is normal but CT is prolonged as in
hemophilia, temporary hemostatic plug is formed
because of normal functioning of platelets but they are
washed off by the flowing blood as definitive hemostatic
plug, i.e. clott is not formed.
123. Mention the conditions when BT and CT is
prolonged.
BT is increased during thrombocytopenic purpura,
allergic and also senile purpura, infection like typhus,
bacterial endocarditis, deficiency of vitamin C, etc.
CT is prolonged in hemophilia, afibrinogenemia, vitaminK deficiency, liver disease, etc.
124. What are the physiological and pathological
variations of platelet count?
Physiological
Increase of count—in severe exercise and high altitude
Decrease of count—in newborn babies and after
menstruation
Pathological
Increase of count—Severe hemorrhage and removal of
spleen.
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Decrease of count—Bone marrow depression, acute
septic fever, aplastic anaemia, toxemia, autoimmunodestruction of platelets, AIDS, etc.
125. What is the basic difference between intrinsic and
extrinsic system of blood clotting?
In the intrinsic system, injury to blood cells like platelets,
releases phospholipid that activate different clotting
factors to induce clotting. Whereas in the extrinsic system
injury to blood vessels or nearby tissues releases tissue
thromboplastin which induces clotting mechanism by
activating different clotting factors by cascade
mechanism.
126. What is prothrombin time? What is its significance?
Prothrombin time is the test for prothrombin activity and
thereby it is a test for testing the extrinsic system of blood
coagulation. Normal value of prothrombin time is 11-16
sec and it is increased in liver failure and deficiency of
vitamin-K. It is generally used to monitor patients with
anticoagulants therapy to adjust its dose.
127. Mention the role of Ca++ in clotting mechanism.
Except for the first 2 steps in the intrinsic pathway calcium
ions are required for the promotion of all reactions
involved in both intrinsic and extrinsic pathway.
128. Why Ca++ deficiency does not produce coagulation
defects?
Only traces of calcium ions are required for coagulation
of blood which are normally available in the body.
129. Why clot does not spread in the injured vessel after
blood coagulation?
The reasons are:
• Removal of some activated clotting factors specially
IX, X, and XII from the circulation by antithrombin III
secreted by the liver.
• Reduction in the supply of clotting factor.
• Balancing activity of thromboxane A2 and prostacyclin
34 VIVA
IN MEDICAL PHYSIOLOGY
that prevent excessive extension of clot and
maintaining blood flow around it.
130. How a balance is maintained between the clotting
mechanism and fibrinolytic system in the body?
Factors that initiate clotting mechanism also stimulate the
dissolution of clot (fibrinolysis) by the following
mechanism.
131. What is purpura? What are its causes?
The purpura is purple coloured petechial hemorrhagic
condition with bruises in the skin due to the degradation
of Hb over a period of time. The causes are
thrombocytopenia, allergy, old age, functional platelet
defects, etc.
132. What is the difference between thrombocytopenia
and thromboasthenia?
Reduction of platelet count below 1.5 lakh/cumm of blood
is known as thrombocytopenia whereas impairment of
platelet functions due to presence of abnormal platelets
are known as thromboasthenia.
133. Name two well known vascular causes of bleeding?
Scurvy and Cushing Syndrome.
134. Why does vit-K deficiency cause bleeding
tendency?
This is due to the facts that Vitamin K deficiency results
in low plasma levels of both procoagulants as well as
some anticoagulants. These proteins are called vitamin
K dependent proteins.
SECTION I : THEORY VIVA
BLOOD 35
135. Why does blood become incoagulable following
violent death?
In case of violent death, the blood remains in fluidic and
incoagulable in nature due to fibrinolysis resulted due to
adrenaline induced rapid release of plasminogen
activators from endothelial cells.
136. What is the difference between rouleaux formation
and agglutination?
Rouleaux formation is simply stacking of RBCs without
any hemolysis whereas in agglutination there is antigenantibody reaction on the red cells resulting hemolysis of
RBC.
137. Name the cold antibodies present in our body.
ABO antibodies are the cold antibodies because they
act best at low temperature, i.e. between 5°C-20oC.
138. Name the warm antibodies present in our body?
Rh-antibody is the warm antibody because they act best
at normal body temperature, i.e. 37°C.
139. What are the indications of blood transfusion?
These are blood loss, blood disorders like hemophilia,
purpura, blood diseases like leukaemia, severe anaemia,
CO poisoning, shock, etc.
140.
What do you mean by major and minor crossmatch? What is its clinical significance?
In the cross-matching technique, the red cells and the
plasma of donor and recepient’s blood are first separated
by centrifugation. Then if the donor’s red cells are treated
with recepients plasma it is known as major cross-match
and if the donor’s plasma is reacted with recepients RBC
it is known as minor cross-match.
If no agglutination takes place in both the occasions
then only the donor’s blood is used to the recepient.
36 VIVA
IN MEDICAL PHYSIOLOGY
141. What is Landsteiner’s law? Is it applicable in all
types of blood groups?
In an individual, if an agglutinogen is present in his RBCs,
the corresponding agglutinin will be absent in his plasma
and similarly if an agglutinin is present in his plasma, the
corresponding agglutinogen will be absent in his RBC.
This law is known as Landsteiner’s law.
This law is not applicable to other blood group systems
as there are no naturally occurring antibodies present in
those systems.
142. In ‘O’ blood group no antigens are there, still both
antibodies are present in plasma. How these
antibodies are formed?
Any of the specific blood group antibodies are absent at
birth but in childhood while taking some foods like seed
and plants or from intestinal bacteria these nonselfantigens are absorbed from GI tract to blood and thereby
induces to develop the antibodies against that particular
antigen or antigens.
143. Name the various Rh-agglutinogens in Rh-system?
These are C,c, D,d, E and e. Of these ‘D’ is clinically
important which may be positive or negative, i.e. present
in blood or absent respectively.
144. Why ABO incompatibilities rarely produce hemolytic
disease of newborn?
It is because the alpha and beta antibodies are of IgM
type of antibodies having large MW. This is why these
can not pass through the placenta to result agglutination
of RBCs.
145. Why the stored blood is not suitable for transfusing
WBCs and platelets to a recipient?
It is because the blood stored for more than 24 hours
does not contain active WBCs and platelets.
SECTION I : THEORY VIVA
146.
BLOOD 37
The term universal donor and universal recipient
are no longer valid. Justify
In both the cases complications can also be produced
due to mismatching of Rh factors and other blood groups.
147. What changes RBCs undergo during cold storage?
Cold storage results following changes:
• appearance of spherocytic RBC due to net increase
in volume of cell .
• increase in tendency of hemolysis.
148. At what age after birth a child’s blood group is set
in it’s true ABO type?
During adolescence i.e. upto 10 years.
149. How hemolytic disease in a newborn can be
prevented?
It is by removing small quantities of infant’s blood
successively from IVC and replacing an equal amount of
compatible Rh- blood.
150.
What is the management of hemolytic transfusion
reactions?
In case of hemolytic transfusion reactions transfusion
must be stopped immediately and the patient is to be
given intravenous injection of rapid acting corticoids.
151.
What do you mean by secretors and nonsecretors?
The A and B antigens are also present in other tissues
like liver, pancreas, kidney, etc. and also in body fluids
like saliva, semen, etc. The individuals who have high
concentration of these antigens in their body fluids are
called secretors and those having low concentration of
these antigens in their body fluid are known as nonsecretors.
152. What are human leucocyte antigens (HLA) and what
is their importance?
HLA are the antigens present on the surface of WBCs.
38 VIVA
IN MEDICAL PHYSIOLOGY
HLA typing is done before tissue or bone marrow
transplant since they are responsible for early rejection
of transplant.
153. Name the factors promoting erythropoiesis.
These are hypoxia, iron, porphyrin, traces of cupper,
cobalt, protein, vitamin-C, thyroxin, hematinic principle,
maturation factor, etc.
154. Why spleen is not essential for life?
The function of spleen can also be maintained by some
other organs and tissues like Kupffer cells in liver, lymph
nodes, subcutaneous tissue, osteoclasts, microglia in
brain, lymphocytes, thymus gland, etc. This is why it is
not essential in life, however in absence of spleen bacterial
infections are more common and severe.
155. Why incidences of tumours are more with
advancing age?
It is because of the gradual declining of cellular immune
mechanism.
156. Why we do not make an immunological response
of our own body proteins?
Body has got the capacity to identify it’s own ‘self’ protein
against of which no immunological response is evoked.
CARDIOVASCULAR SYSTEM 39
SECTION I : THEORY VIVA
1.3
Cardiovascular System
1. What structural characteristics of cardiac muscle
enable its continuous rhythmic contractions?
These are: Presence of pacemaker cell that initiates
autorhythmicity, presence of special conductive tissue
and presence of free branchings between the muscle
fibres (syncytium) ensure the quick passage of impluse
from pacemaker cell to all parts of heart to initiate
continuous rhythmic contractions.
2. Name the special conducting tissues of heart.
SA node, AV node, bundle of His and Purkinje fibre.
3. What is cardiac pacemaker?
SA node is called as the cardiac pacemaker because it
is made up of ‘P’cells which can generate the impulse
more rapidly than any of the pacemaker tissue of heart
and thereby determine the rate at which the heart beats.
4. What is law of heart muscle?
It states that the size of muscle fibers, glycogen content
and rate of conduction increases from nodal to Purkinje’s
fiber whereas length of systole, duration of refractory
period and rhythmicity increases in the reverse direction.
5. What is intercalated disc and what is its
importance?
At the point of contact of two cardiac muscle fibers,
extensive folding of cell membrane occurs which is known
as intercalated discs. They provide a strong union
40 VIVA IN MEDICAL PHYSIOLOGY
between fibers so that the pull of one contractile unit can
be transmitted to the next, thereby helps in increasing
force of contraction.
6. What is the role of gap junction in cardiac muscle?
Gap junction is present in the intercalated disc of cardiac
muscle fibers and helps in rapid transferring of electrical
currents, ions, etc. from one cell to another without coming
in contact with ECF. Thus they provide low resistance
bridge for the rapid spread out of electrical impulse,
thereby helps the cardiac muscle to act as syncytium
(functional).
7. Name the valves and their location.
There are 4 valves—two in between the atria and
ventricles known as atrio-ventricular valves (A-V valves)
and two are at the opening of the blood vessels arising
from the ventricles (semilunar valves).
a. A-V valves: These are present in between the atria
and ventricles. The valve present in between right
atria and right ventricle is known as Tricuspid valve
and the valve present in between left atria and left
ventricle is known as Bicuspid valve.
b. Semilunar valves: There are two semilunar valves
namely Pulmonary valve and Aortic valve. The
pulmonary valve is present at pulmonary orifice which
leads from RV to pulmonary artery and the aortic valve
is present at aortic orifice which leads from LV to the
aorta.
8. Name the special junctional tissues and their
conduction rate.
The special junctional tissues and their rate of impulse
generating capacity are:
Special junctional tissues
Impulse generating capacity
S A Node
A V Node
Bundle of His
Purkinje’s fiber
75 ± 5 times/min
60 times/min
40 times/min
20 times/min
SECTION I : THEORY VIVA
CARDIOVASCULAR SYSTEM 41
9. What do you mean by pacemaker potential or
diastolic depolarisation?
The pacemaker tissue is characterised by unstable RMP
due to slow depolarisation resulting from leakage of Na+
from outside to inside through Na+ leak channels. This
show leakage of Na+ inside the cell causes increase in
electropositively inside the cell which ultimately enables
to induce another action potential easily. This slow
polarisation in between action potential is known as
prepotential or pacemaker potential or diastolic
depolarisation.
10. Why SA node is called as cardiac pacemaker?
SA node acts as a pacemaker of heart because the
rate of impulse generation in normal heart is determined
by this node because of its highest rate of impulse
generating capacity (75 ± 5 times/min) than other
junctional tissues. This is why it is known as cardiac
pacemaker.
11. What is ectopic pacemaker?
When the pacemaker is other than SA Node (e.g. AV
node, etc.) it is called as ectopic pacemaker.
12. What do you mean by nodal and idioventricular
rhythm?
The AV node takes the charge of generating impulse
rhythmically when SA node does not work. In this condition
atria and ventricles beat almost simultaneously at the
rate of 60 times per min. This rhythm of heart is known
as Nodal rhythm. Whereas 2nd Stannius ligature applied
over the A-V groove makes the atria to continue beating
with it’s own rhythm whereas the ventricle stops beating
due to blockade of impulse from atria to ventricles. After
sometimes ventricle generates it’s own impulse and starts
beating at much slower rate. This rhythm of heart beat in
which atria and ventricular beating do not follow any
specific pattern is known as idioventricular rhythm.
42 VIVA IN MEDICAL PHYSIOLOGY
13. What is AV delay? What is its significance?
When the impluse reaches to AV node, there is a delay
of about 0.1 sec to pass the impulse to bundle of His.
This time gap is known as AV delay. It allows the atria to
contract just ahead of ventricular contraction thereby atria
is emptied before ventricular ejection.
14. What is Frank-Starling's law?
Within the physiological limit the larger the initial length
of muscle fiber (end diastolic fiber length), the greater
will be the force of contraction of the heart which is known
as Frank-Starling's law of heart.
15. What is the ionic basis of plateau phase of cardiac
action potential?
Immediately after depolarisation voltage gated Na+
channel's used to close resulting stoppage of entry of
Na+ ions and voltage gated K+ channel starts opening
resulting exit of K + . These result rapid fall of
electropositivity initially known as rapid repolarisation.
Afterwards, the rate of repolarisation becomes slower due
to prolonged opening of voltage gated Ca+2 channel
through which Ca+2 enters inside. Thus the exit of K+ is
almost counterbalanced by entry of Ca+2 resulting
sustained depolarisation known as plateau phase.
16. Is all or none law applicable in heart?
All or none law which states that if a stimulus is applied,
whatever may be the strength of stimulus, the cardiac
muscle responds maximally or it does not give any
response at all. Of course it is applicable only in whole
artrial muscle (i.e. atrial syncitium) or in whole ventricular
muscle (i.e. ventricular syncitium) not to a single cardiac
muscle fiber.
17. Why left ventricular subendocardial region is more
prone to myocardial infarction?
The blood supply to the cardiac muscle in different areas
of heart is not same. On the surface of the cardiac muscle
SECTION I : THEORY VIVA
CARDIOVASCULAR SYSTEM 43
there are large epicardial arteries supplying more blood
to those areas whereas in the subendocardial region
blood supply is less because it is supplied by smaller
intramuscular arteries and plexus of subendocardial artery
the diameter of which are less. This blood supply to the
subendocardial plexus is further reduced during systole.
Therefore the subendocardial region is more prone
to myocardial infarction. Again as the left ventricular
thickness is much more than that of right ventricle the
occlusion is more severe in left ventricle. For this region
LV subendocardial region is more prone to MI.
18. What are the importance of anastomatic channels
in heart muscle?
In the normal heart there are some collaterals among
the smaller arteries which become active under abnormal
conditions like myocardial ischemia. They open up within
a few seconds after the sudden occlusion of larger artery
and become double in number by the end of 2nd or 3rd
day and reach to normal by one month. When
atherosclerosis causes constriction of coronary arteries
slowly over a period of many years, collateral vessels
develop restoring normal blood and thus the patient
never experiences acute episode of cardiac
dysfunction.
19. What is the importance of autoregulation in blood
supply in heart muscle?
Like some other organs the heart has the capacity to
regulate it’s own blood flow up to a certain limit in order
to maintain an almost constant blood flow to the cardiac
musculature inspite of any alteration of systemic blood
flow. This is known as autoregulation of coronary blood
supply.
20. What is angina pectoris?
Due to myocardial ischemia there is stimulation of
nociceptors present in heart muscle resulting pain
sensation which is normally referred to upper sternum,
44 VIVA IN MEDICAL PHYSIOLOGY
left forearm, left shoulder, neck and side of the face. This
clinical condition is known as angina pectoris.
21. Why cardiac muscle cannot be tetanised?
It is because of it's long absolute refractory period and
thus summation of contractile response is not possible
which is essential for tetanisation of heart muscle.
22. What is staircase effect in heart muscle?
When the cardiac muscle begins to contract after a brief
period of rest (e.g. following vagal stimulation) its initial
length of contraction increases before reaching to a
plateau. This phenomenon is called as staircase effect
or treppe response.
23. What is cardiogram?
The record of the mechanical activity of the heart is known
as cardiogram.
24. Mention the maximum and minimum pressure in
heart during systole and diastole?
Chamber
Peak pressure in systole
Min. pressure in diastole
Left ventricle
Right ventricle
Left atrium
Right atrium
Aorta
120 mm Hg
25 mm Hg
15 mm Hg
6 mm Hg
120 mm Hg
5-12 mm Hg
2-6 mm Hg
5-8 mm Hg
1-5 mm Hg
80 mm Hg
Pulmonary artery
25 mm Hg
5-12 mm Hg
25. Define and give normal values of end diastolic
volume, stroke volume and end systolic volume.
During ventricular diastole the intraventricular volume is
increased which results filling of the ventricles. At the
end of diastole the amount of blood filled by the ventricle
is known as end diastole volume (EDV). It is about 120130 ml.
During ventricular systole intraventricular volume
decreases which results increase in pressure thus
SECTION I : THEORY VIVA
CARDIOVASCULAR SYSTEM 45
ejection of blood out of ventricles. During each systole
the amount of blood pumped out by each ventricle is
known as stroke volume (SV). Normal value:70 ml/beat.
At the end of systole however some amount of blood
is remained in each ventricle which is known end systolic
volume (ESV). The normal volume: 50-60 ml/ beat.
26. What do you mean by vagal escape? What is its
cause?
If strong vagal stimulation to heart is continued then after
a pause the ventricles resume to beat at a slow rhythm
which is called as vagal escape represented by the Figure
1.3.1.
Fig. 1.3.1: Demonstration of vagal escape on heart muscle
During prolonged vagal stimulation right auricle stops
beating and distends due to blood overflow which leads
to fall of BP → afferent impulse from carotid sinus to
cardiac centers →stimulate ventricles to start its beat.
27. Define apex beat.
Apex beat is the impulse or throb which is felt and seen
on the chest wall normally in the left 5th intercostal space
just medial to left nipple.
28. Name different phases of cardiac cycle. Mention
the duration of each phase.
Phases of cardiac cycle
Duration in sec
a)
b)
c)
0.1
0.7
0.3 Total
0.05
Atrial systole
Atrial diastole
Ventricular systole
i) Isovolumetric contraction
Contd...
46 VIVA IN MEDICAL PHYSIOLOGY
Contd...
Phases of cardiac cycle
d)
ii) Rapid ejection phase
iii) Slow ejection phase
Ventricular diastole
i) Protodiastole
ii) Isovolumetric relaxation
iii) Filling phase
• Ist rapid filling phase
• Slow filling phase
• Last rapid filling phase
Duration in sec
0.1
0.15
0.5 Total
0.04
0.08
0.38 Total
0.1-0.12
0.18-0.20
0.06-0.10
29. What is protodiastole? Is it part of systole or
diastole?
Protodiastole is the very brief phase before diastole in
which ventricular systole has ceased but relaxation yet
to start.
It can not be well defined whether the protodiastole is
a part of systole or diastole as some workers include it in
diastole as muscle contraction is stopped at this phase
whereas some others believe that it is a part of systole
as muscle relaxation has not yet started.
30. Define cardiac cycle.
The sequence of events (mechanical,electrical, etc.)
associated with consecutive heart beat is repeated
cyclically which is known as cardiac cycle. Normal duration
is 0.8 sec if heart rate is 75 beats/min.
31. What are the causes of 1st heart sound?
These are:
i. Closure and vibrations of AV valves at the
beginning of ventricular systole.
ii. Vibrations of blood surrounding the AV valves.
iii. Vibrations of major blood vessels around the heart.
iv. Vibrations of walls of heart.
32. What are the characteristics of 1st heart sound?
It is:
• Soft, prolonged with low pitch.
SECTION I : THEORY VIVA
•
•
CARDIOVASCULAR SYSTEM 47
Duration is 0.12 sec and occurs in peak or downstroke
of R wave in ECG and just before onset of ‘c’ wave in
jugular pulse tracing.
Best heard at apex beat area and is associated with
onset of ventricular systole.
33. What is the significance of 1st heart sound?
It indicates force of contraction, condition of myocardium
and competence of AV valves.
34. What are the causes of 2nd heart sound?
These are:
Closure and vibration of semilunar valves at the end of
ventricular systole.
Vibrations of blood surrounding these valves.
Vibrations of walls of aorta and pulmonary artery.
Vibrations of the wall of ventricles to a little extent.
35. What are the characteristics of 2nd heart sound?
It is:
• Sharp, short and high pitched.
• Duration is 0.08 sec and follows T wave in ECG and
coincides with ‘v’ wave in jugular venous pulse tracing.
• Best heard at 2nd right costal cartilage for aortic
component and 2nd intercostal space at left sternal
border for pulmonary component.
• Associated with onset of ventricular diastole.
36. What is the significance of 2nd heart sound?
It indicates the competence of semilunar valves.
37. When and how 3rd heart sound is produced?
3rd heart sound is produced during the first 1/3 of
ventricular diastole. It occurs due to the vibrations set up
by the rushing of the blood during the rapid filling phase
of ventricular diastole.
48 VIVA IN MEDICAL PHYSIOLOGY
38. Differentiate 1st and 2nd heart sound.
1st heart sound
i.
It is prolonged, lowpitched
and soft.
ii. Coincides with carotid pulse
iii. Coincides with R wave of ECG
iv. Best heard over the mitral area
v. Time interval between 1st
and 2nd is shorter
2nd heart sound
It is sharper, abrupt, clear and high
pitched
Does not coincide
May precede, coincide or follow the T
wave of ECG.
Best heard over aortic and pulmonary
area.
Time interval beween 2nd and next
1st is comparatively longer.
39. What is murmur?
It is the sound produced by turbulence produced in the
blood by a forward flow through a stenosed (narrowed)
valve or back flow (regurgitation) through a deformed or
incompetent valve.
40. How do you classify murmur?
It will be classified on the basis of their relationship with
main heart sounds like presystolic, systolic, diastolic and
also to and fro murmurs.
41. What are the maximum and minimum pressure in
heart?
• Maximum pressure in left ventricle is above 120 mm
Hg.
• Max pressure in right ventricle is above 25 mm Hg.
• Minimum pressure in left ventricle is 80 mm Hg.
• Minimum pressure in right ventricle is few mm Hg.
42. What is the normal heart rate? What are the factors
affecting heart rate (HR)?
Normal value of HR is 72 beat/min with the normal range
is 60-90 beat/min.
The factors are: age, sex, body temperature, hypoxia,
emotion, exercise, etc. and drugs like epinephrine and
norepinephrine.
SECTION I : THEORY VIVA
CARDIOVASCULAR SYSTEM 49
43. Why HR is slightly higher in females than males?
It is because of two reasons:
• Lower systemic BP
• More resting sympathetic tone.
44.
What is Cushing reflex?
It is represented by following sequential events:
Increased intracranial pressure → decreases blood
supply to medullary hypoxia and hypercapnia →
stimulation of medulary vasomotor center →increase of
systemic BP →stimulation of baroreceptors →stimulation
of vagus nerve →decrease of HR and respiration. This
reflex mechanism by which increased intracranial
pressure results bradycardia is known as Cushing reflex.
45. What do you mean by sinus arrhythmia?
Heart rate increases with inspiration and decreases
during expiration. This phenomenon is known as sinus
arrhythmia.
46. State Mary’s law.
If the other conditions remain constant then the HR is
inversely related with systemic BP.
47. Define cardiac output, stroke volume and cardiac
index.
Cardiac output: The amount of blood pumped out by each
ventricle per min is called as cardiac output. The normal
value is 5 lit/min/ventricle.
Stroke volume: The amount of blood pumped out by each
ventricle in each beat is known as stroke volume. Normal
value is 70 ml/beat/ventricle.
Cardiac index: It is the cardiac output per square meter
of body surface area. The normal value is 3.2 L/m2/min.
48. What do you mean by extrinsic and intrinsic
autoregulation of cardiac output?
If cardiac output is controlled by controlling only heart
rate (as CO = HR × SV) it is known as extrinsic
autoregulation of cardiac output whereas if it is regulated
50 VIVA IN MEDICAL PHYSIOLOGY
by regulating only stroke volume, it is known as intrinsic
autoregulation.
49. What is the difference between heterometric and
homometric regulation of cardiac output?
To control cardiac output when ventricular contraction is
regulated by controlling initial length of the muscle fibre,
i.e. EDFL, then it is called as heterometric regulation
which is independent of cardiac nerves. Whereas when
cardiac nerves regulate the myocardial contractility to
control the cardiac output, it is known as homometric
regulation of cardiac output.
50. What is Frank-Starling’s law of heart? What is its
relation with venous return?
It states that within the physiological limit, the force of
ventricular contraction is directly proportional to the initial
length of muscle fibres (EDFL).
If venous return is increased the EDFL of the ventricular
muscle is also increased resulting more force of
ventricular contraction thereby more cardiac output.
51. What do you mean by Vis A Tergo and Vis A Fronte
in relation to cardiac pump?
Vis A Tergo is the force which drives the blood forward
from behind, e.g. the contraction of the heart drives the
blood in forward direction, whereas Vis A Fronte is the
force acting from front that attracts blood in the veins
towards the heart, e.g. ventricular systolic and diastolic
suction pressure.
52. Enumerate the factors affecting venous return.
The factors are: Thoracic or respiratory pump, cardiac
pump, muscle pump, total blood volume and increased
sympathetic activities on veins.
53. Name two methods by which cardiac output is
measured.
These are:
• Direct Fick method and
• Indirect dye dilution method.
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CARDIOVASCULAR SYSTEM 51
54. Enumerate Fick’s principle.
It states that the amount of a substance taken up by an
organ or by whole body per unit time is equal to the arterial
level of that substances minus the venous level (i.e. A-V
difference) times the blood flow, i.e. amount of substance
taken/min = A-V difference of the substance × blood flow/
min.
55. What are the disadvantages of Fick’s method?
These are:
• As it is the invasive method the subject is exposed to
all risk of hemorrhage, infection, etc.
• As the subject is conscious of the whole technique
cardiac output may be higher than normal.
56. Which dye is generally used in Dye dilution method
and why?
It is generally Evans blue or radio-active isotopes. Criteria
for selection are as follows:
• These stay in the circulation during the test.
• These are not harmful and not toxic.
• Do not alter the hemodynamics of blood flow.
• Concentration of these substances can be easily
measured.
• Excreted totally and neither reabsorbed nor secreted
by the body.
57. What is Ballistocardiogram?
It is a record of the to and fro movements of the body in
the headward to footward direction when the subject lies
on a suitably suspended table. This is the another method
of measuring cardiac output though it is now absolute.
58. What is Bundle of KENT?
In the individuals with WPW syndrome, there is one
additional nodal connecting tissue in between atria and
ventricles besides AV node which conducts the impulse
more rapidly than AV node. This additional conducting
pathway is known as Bundle of KENT.
52 VIVA IN MEDICAL PHYSIOLOGY
59. Define blood pressure (BP).
It is the lateral pressure exerted by the moving column of
blood on the wall of blood vessels during its flow.
60. Define systolic, diastolic, mean and pulse pressure
with each of their normal average values.
Systolic pressure (SP): It is the maximum pressure exerted
during systole of the heart. Normal value = 120 mm Hg
(Normal range:110-140 mm Hg).
Diastolic pressure (DP): It is the minimum pressure during
diastole of the heart. Normal value = 80 mm Hg (Normal
range: 60-90 mm Hg).
Pulse pressure (PP): Pulse pressure is the difference
between systolic and diastolic pressure. Normal value =
40 mm Hg.
Mean pressure: It is average pressure during each
cardiac cycle. Normal value = 93.3 mm Hg.
61. Enumerate the significance of SP, DP, PP and MP.
• Systolic pressure indicates the extent of work done
by the heart and also the force with which the heart is
working. It also indicates the degree of pressure the
arterial wall have to withstand.
• Diastolic pressure is the measure of the total peripheral
resistance and it indicates the constant load against
which heart has to work.
• Pulse pressure determines the pulse volume. Whereas
mean pressure indicates the perfusion pressure head
which causes the flow of blood through the arteries,
arterioles, capillaries, veins and venules.
62. Why does systolic pressure increase after meal?
After meal pressure over heart increases due to
distended abdomen which in turn increases heart rate
and also there is a release of epinephrine which also
increases systolic blood pressure.
SECTION I : THEORY VIVA
CARDIOVASCULAR SYSTEM 53
63. What do you mean by baroreceptors? Where are
they located?
Baroreceptors are the pressure receptors stimulated in
response to change of pressure around them.
These are located in the wall of blood vessels (e.g. arterial
baroreceptor–present in carotid sinus, aortic arch, root
of right subclavian artery, junction of thyroid artery with
common carotid artery, also pulmonary trunk) and also
in the walls of the heart (e.g. atrio-caval receptors, atrial
receptors).
64. What do you mean by buffer nerves? Why they are
so called?
Carotid sinus nerve originated from carotid sinus and
aortic nerve arised from arch of aorta are collectively
known as buffer nerves as they prevent any change in
systemic BP and thus help the BP to keep normal.
65. What is Bainbridge reflex?
Rapid injection of blood or saline in anesthetised animals
produces a rise in heart rate if the initial heart rate is low.
This is called as Bainbridge reflex.
66. Name different chemoreceptors responsible for BP
regulation. What are their stimulants?
These are carotid bodies and aortic bodies. They get
stimulated by hypoxia, hypercapnia, asphyxia and also
acidemia.
67. Sudden standing increases diastolic BP—explain
how?
On standing there is peripheral pooling of blood in lower
parts of body →lowering of venous return to the heart
→decrease cardiac output → thereby decrease systolic
BP → leads to decrease baroreceptor discharge →
thereby increases sympathetic activity →results increase
of the total peripheral resistance due to vasoconstriction
→ultimately leads to increase of diastolic pressure.
54 VIVA IN MEDICAL PHYSIOLOGY
68. If mean BP is decreased to 60 mm Hg then what
compensatory mechanism will operate to bring it
normal?
Both baroreceptor mechanism (which operates in
between 60-200 mm Hg mean blood pressure) and
chemoreceptor mechanism which operates between 40100 mm Hg of mean BP.
69. If BP is decreased to 40 mm Hg then which
compensatory mechanism will start into action?
Both chemoreceptor mechanism and CNS ischemic
response.
70. If mean BP is increased to 140 mm Hg then what
compensatory mechanism will be operated?
Only baroreceptor mechanism.
71. What do you mean by stress relaxation and reverse
stress relaxation mechanism in relation to BP
regulation?
Rise in arterial BP due to intravenous transfusion of blood
increases perfusion pressure in blood storage organs
that causes relaxation of blood vessels, thereby
decreases venous return and thereby decreases cardiac
output. This leads to decrease BP to normal level. This
mechanism is known as stress relaxation.
The opposite phenomenon is known as reverse stress
relaxation mechanism which is as follows:
Prolonged bleeding causes decreases of BP →thereby
decreases perfusion pressure → leads to
vasoconstriction of blood storage organs → results
increase of venous return and thus increases cardiac
output →which in turn increases BP to normal level.
72. What is hypertension? What do you mean by systolic
hypertension and white coat hypertension?
Chronic elevation of blood pressure beyond 140/90 is
generally labelled as hypertension. In advanced age, due
to loss of elasticity of blood vessels, stretching of the wall
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CARDIOVASCULAR SYSTEM 55
of blood vessels decreases which results in increasement
of pressure during systole with normal diastolic pressure.
This condition is known as systolic hypertension which is
characterised by high pulse pressure.
Some hypertensive patients because of nervousness,
have higher BP in the clinician’s chamber than during
their normal day time activity. This condition is known as
white coat hypertension.
73. What do you mean by malignant hypertension?
In some patients the blood pressure especially the
diastolic pressure is increased to very high level (>120
mm Hg) within a short period. This condition is known as
malignant hypertension.
74. Which pressure is considered better to judge the
hypertension–SP or DP? Justify your answer.
Clinically diastolic pressure is more useful to characterise
the state of hypertension because diastolic pressure is
comparatively constant and does not fluctuate like SP in
response to day to day activity.
75. What do you mean by labile hypertension?
In early stages of essential hypertension, systolic BP
fluctuates. This is why it is referred as labile hypertension.
76. What is hypotension?
Chronic low BP specially the diastolic pressure below 60
mm Hg is called as hypotension.
77. What do you mean by postural hypotension?
In some hypotensive patients, sudden standing causes
further fall of systemic BP that may result dizziness,
dimness of vision and even fainting. This is known as
postural hypotension.
78. What is the difference between pulse pressure and
pressure pulse?
Pulse pressure is the difference of systolic and diastolic
pressure whereas the pressure pulse or pulse is the wave
transmitted to the arteries like radial arteries due to
56 VIVA IN MEDICAL PHYSIOLOGY
stretching and relaxation of wall of aorta in response to
ventricular ejection of blood and ventricular filling
respectively during cardiac cycle.
79. What is the purpose of doing exercise tolerance
test?
It is for determining the efficiency of the heart as a
pumping organ.
80. What is cardiac reserve?
It is the difference between the basal cardiac output of
an individual and the maximum cardiac output that can
be achieved in that person. It is also expressed as cardiac
reserve percent.
81. By observing HR can you predict the intensity of
exercise or work done by a person?
Yes, - If HR is <100 ; it will be light exercise.
- If HR is 100-125 ; it will be moderate exercise.
- If HR is 126-150 ; it will be heavy exercise.
- If HR is >150 ; it will be severe exercise.
82. Where do you find physiological bradycardia?
It is seen in athelets, during sleep and meditation.
83. What is apex-pulse deficit?
Normally the pulse rate and heart rate are identical but
in some cases like extra-systoles and atrial fibrillations,
some of the heart beats are too weak to be felt at the
radial artery resulting missing of that particular pulse.
This causes higher heart rate than pulse rate. This
condition is known as apex-pulse deficit or pulse deficit.
84. Name the waves of normal arterial pulse tracing.
What are their physiological basis?
In the normal arterial pulse recording, there are one steep
upstroke called anacrotic limb and one rather slow down
stroke called catacrotic limb. The end of anacrotic limb
and beginning of catacrotic limb is designated as
percussion wave (p). In the catacrotic limb there is also a
negative wave called dicrotic notch (n) followed by a
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CARDIOVASCULAR SYSTEM 57
positive wave called dicrotic wave. Besides this, sometimes
after the peak of the tracing there is another small wave
called tidal wave (t). The waves are represented by
Figure 1.3.2.
Fig. 1.3.2: Normal arterial pulse tracing
a. Percussion wave: It is due to expansion of the artery
for ventricular ejection during ventricular systole.
b. Catacrotic limb: It is due to normalisation of artery due
to slow passing of blood towards periphery.
c. Dicrotic notch: It is due to backflow of the blood from
aorta towards heart due to pressure difference during
ventricular diastole.
d. Dicrotic wave: It is due to increase pressure again in
the aorta due to prevention of back flow of blood
towards heart by closure of aortic valve.
85. Can you indicate the systolic and diastolic phases
of the ventricle on the arterial pulse tracing?
Yes, the maximum ejection phase lasts from the start of
the upstroke to peak of ‘p’ wave while the reduced ejection
phase lasts from peak of ‘p’ wave to peak of dicrotic notch.
The rest time period represents diastole.
86. What is dicrotic pulse?
There are two palpable waves- one in systole and another
in diastole in congestive cardiomyopathy patients where
stroke volume is low. This type of pulse is known as dicrotic
pulse.
87. What is plateau pulse?
During some pathological conditions like aortic stenosis
the pulse wave rises slowly, followed by delayed and
58 VIVA IN MEDICAL PHYSIOLOGY
sustained peak and then the pulse faded slowly. Such
type of pulse is known as plateau pulse as represented
by Figure 1.3.3
Fig. 1.3.3: Abnormal arterial pulse tracing (plateau pulse)
88. What is anacrotic pulse?
Slow rising and slow fall of pulse wave due to prolonged
ventricular ejection as occurs in aortic stenosis is known
as anacrotic pulse.
89. What do you mean by pulsus alterans and
paradoxus?
Pulsus alterans is alternative weak and strong beating of
pulse whereas the phenomenon when pulse disappears
or becomes feeble during inspiration and becomes
maximum during expiration is known as pulsus paradoxus.
90. What is water hammer pulse?
In some conditions like aortic regurgitation there is sharp
and steep rise followed by sleep fall of pulse which is
known as water hammer pulse.
91. How does jugular venous pulse record give the
idea about right atrial pressure?
Jugular vein is connected directly with right atrium and
as there is no valve at the junction of superior vena cava
and right atrium, any change of right atrial pressure is
directly transmitted to the jugular vein. That is why jugular
venous pressure record gives the idea about right atrial
pressure.
92. Name the waves of jugular venous pulse and the
causes of their onset.
The waves and their causes are as follows:
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•
•
•
•
CARDIOVASCULAR SYSTEM 59
‘a’ wave – It is due to increase in pressure within atrium
due to atrial systole.
‘c’ wave – It is due to increased pressure within atrium
due to bulging of the tricuspid valve into the right
atrium during isovolumic ventricular contractile phase.
‘v’ wave – It is due to the rise in atrial pressure due to
atrial filling before the tricuspid valve opens during
diastole.
X descends-It is due to fall of intra-atrial pressure due
to descend of the tricuspid valves.
Y descends-It is due to the fall of intra-atrial pressure
due to the opening of tricuspid valves to result
ventricular filling.
93. Define ECG.
It is the record of electrical activities of heart by
electrocardiograph during different periods of cardiac
cycle.
94. Enumerate the clinical significance of ECG.
Any abnormalities of the heart like ischemic heart disease,
myocardial infraction, extrasystole, heart block,
ventricular fibrillation and flutter, sinus arrhythmias, etc.
are detected by the ECG record of the person.
95. What does ‘P’ wave represent? What does it
signify?
‘P’ wave represents the atrial depolarisation. Any
abnormalities of the ‘P’ wave means abnormality in the
atria like larger ‘P’ wave denotes the atrial hypertrophy.
96. What do QRST and QRS represent? What is the
duration of ventricular complex?
QRST represents ventricular complex, i.e. ventricular
depolarisation and ventricular repolarisation. Normal
duration is 0.48 sec.
QRS complex represents ventricular depolarisation only.
97. What do Q and RS waves indicate?
‘Q’ wave indicates the ventricular septal activity whereas
60 VIVA IN MEDICAL PHYSIOLOGY
‘RS’ wave indicates the excitation of ventricle proper with
duration of 0.08-0.1 sec.
98. What is the significance of T wave?
It is due to repolarisation of ventricles and its normal
duration is 0.27 sec. It indicates the functional activity of
base of the heart. Clinically it signifies the myocardial
damage in case of any abnormality in T wave.
99. What does PR interval represent? What is its
significance?
It represents atrial depolarisation and conduction through
bundle of His. Normal duration is 0.13-0.16 sec.
It is the interval from beginning of P wave to the beginning
of Q or R wave. Prolonged PR interval signifies the
conduction block.
100. What is TP interval and what is its significance?
It is the period from the end of T wave to the beginning of
P wave of next cardiac cycle. It represents the diastole or
polarised state of whole heart. Normal duration is 0.2
sec at a HR of 75/min.
101. What is QT interval and what does it represent?
It is the interval from the beginning of Q wave to the end
of T wave (Normal duration 0.40-0.43 sec). It represents
ventricular events.
102. What is ST interval? What does it represent?
End of S wave to the end of T wave is known as ST
interval. The normal duration of which is 0.32 sec. It
represents ventricular repolarisation only.
103. What is ST segment? What is its significance?
Following the QRS there is a long isoelectric period which
extends from the end of S wave to the beginning of T
wave called as ST segment. Any change of the position
of ST segment from the isoelectric line indicates the
functional abnormalities of the heart. Deviation of ST
segment more than 2 mm up from the isoelectric line is
called elevated ST segment which is the clinical feature
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CARDIOVASCULAR SYSTEM 61
of MI. Similarly deviation of the same more than 2 mm
downward from the isoelectric line is called as depressed
ST segment as seen in angina pectoris.
104. Define lead.
The electrocardiographic connections, i.e. wires along
with the electrodes to record ECG is known as lead.
105. Classify leads.
Leads are classified as unipolar and bipolar leads which
are again divided as follows:
• Unipolar lead
• Unipolar augmented limb lead
– aVR
– aVL
– aVF
• Chest lead (V1-V6)
• Bipolar lead
– Standard limb lead—I
– Standard limb lead—II
– Standard limb lead—III
106. Why unipolar lead is so called?
In this type of leads, one electrode becomes inactive
(indifferent electrode) whereas other one is active
(exploring electrode). That is why it is known as unipolar
lead.
107. What do you mean by rule of thumb?
It is the general observation in the ECG record obtained
from chest leads as follows:
a. As we pass across the chest leads (V1- V6) ‘R’ wave
increases gradually in size and ‘S’ wave becomes
smaller gradually. In lead V3 both are equal.
b. R wave in V6 and S wave in V1 represent left ventricular
activity whereas R wave in V1 and S wave in V6
represent right ventricular activity.
108. What is augmented limb lead? Why is it so called?
Augmented limb leads are unipolar type limb leads with
slight modification in the recording technique where one
62 VIVA IN MEDICAL PHYSIOLOGY
electrode (active) is connected to the positive terminal of
ECG machine and other two are connected through
electrical resistant to the negative terminal of the ECG
machine.
It is so called because the magnitude of different waves
become larger by 50 per cent than the same obtained
from standard limb leads without any change of its normal
pattern. These are classified as aVR, aVL and aVF.
109. What do unipolar chest leads represent?
V1 and V2 are associated with right atrial and ventricular
activity respectively whereas V4, V5 and V6 represent left
ventricular activity. V3 is regarded as transitional zone.
110. What do you mean by dextocardiogram?
In case of damage of left branch of bundle of His, the
impulse travels through right branch to the right ventricle
resulting predominant activity of right ventricle. Such a
record is called as dextocardiogram.
111.
What is levocardiogram?
When right branch of bundle of His is damaged there is
predominance of left ventricular activity. This type of
record is called as levocardiogram.
112. What do you mean by Einthoven’s triangle?
The equilateral triangle obtained by connecting the right
arm, left arm and right leg, by means of electrical wires
with current source as the heart at its centre is known as
Einthoven’s triangle.
113. What is Einthoven’s law?
It states that if the electrical potentials of any two of the
three bipolar leads are known at any given instant, the
3rd one can be determined mathematically from the 1st
two by simply summing the 1st two by considering the
positive and negative signs of the different leads.
114. What is J point? What is its significance?
J point is the end point of S wave and beginning of ST
segment where there is no electrical activity of the heart
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CARDIOVASCULAR SYSTEM 63
exists. Normally the J point locates on the isoelectric line.
Upward or downward deviation of this point indicates the
heart diseases like MI and cardiac ischemia.
115. What is vector?
It is an arrow that points the direction of the electrical
potential generated by the current flow with the arrowhead
in the positive direction.
116. Mention the characteristics of vector.
These are:
a. Direction of current flow is represented by the arrowhead and
b. Length of the arrow is drawn proportionate to the
voltage of the potential.
117. What do you mean by vector cardiogram?
Vector of current flow through the heart changes rapidly
as the impulse spreads through the heart muscle. These
changes are:
a. The vector increases and decreases in length
because of the increasing and decreasing voltage of
the vector.
b. It also changes direction accordingly with the changes
in the average direction of the electrical potential of
the heart.
The record that shows these changes in the vectors
at different times during the cardiac cycle is called as
vector cardiogram.
118. What do you mean by electrical axis of the heart or
cardiac vector?
Since the standard limb leads I, II, III are records of the
potential difference between two points, therefore,
deflection in each lead at any point indicates the
magnitude and direction in the axis of the electromotive
force generated in the heart. This is called as electrical
axis of the heart.
64 VIVA IN MEDICAL PHYSIOLOGY
119. What do you know about U wave in ECG?
It is rarely seen as a small positive round wave after the
T wave. It is due to slow repolarisation of papillary muscles.
It is more commonly seen in children.
120. What do you mean by left and right axis deviation?
From the ECG record how can you assess whether
any person is having left or right axis deviation?
If the normal direction of mean QRS vector falls in between
–30° to +30°, it is called as left axis deviation which
represents the horizontal position of heart. Similarly, if it
falls in between +75° to +110°, it is known as right axis
deviation which also represents vertical position of heart.
Clinically axis deviations are made by finding the amplitude
of R wave in the bipolar leads as follows:
a. If R wave is the tallest in lead II, it is normal electrical
axis of heart (+59°).
b. If R wave is the tallest in lead I, it is left axis deviation.
c. If R wave is the tallest in lead III it is called as right axis
deviation.
121. What are the physiological left or right axis
deviation? What is the clinical significance of
electrical axis of heart?
Physiological left axis deviation is seen:
a. During expiration
b. When a person lies down
c. If the person is stocky and fatty.
Physiological right axis deviation is seen:
d. During inspiration
e. When a person stands up
f. Normally in tall and lanky people.
Clinical significance: Hypertrophy of any ventricles and
bundle branch block is indicated from the electrical axis
of heart. In patients with hypertrophy of left ventricle and
left bundle branch block, left axis deviation is seen
whereas in hypertrophy of right ventricles and right
bundle branch block patients, right axis deviation takes
place.
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122. What is the difference between 1st degree and 2nd
degree heart block?
When all atrial impulses reach the ventricles therefore
atrial rate: ventricular rate becomes 1:1 but PR interval
becomes longer than 0.2 sec, it is called as 1st degree
incomplete heart block.
Whereas when all atrial impulses are not conducted
to the ventricles producing atrial and ventricular
contraction at a rate of either 2:1 or 3:1 ratio with gradual
lengthening of PR interval till one ventricular beat is
missed, this type of heart block is known as 2nd degree
incomplete heart block.
123. What do you mean by Wenckebach phenomenon?
In case of 2nd degree heart block, there is a gradual
increase of PR interval untill one ventricular beat is
missed.This is known as Wenckebach phenomenon.
124. What is 3rd degree heart block? What do you mean
by idioventricular rhythm?
Complete blockade of conduction of impulse from atria
to ventricle is known as third degree or complete heart
block.
In the case of complete heart block, ventricle starts
beating at its own rate, i.e. 45 beats/min which is
independent to SAN. This rhythmic ventricular contraction
is known as idioventricular rhythm.
125. What is the difference between flutter and
fibrillation?
Flutter
Fibrillation
1. This is due to spreading
of regular circus movement
of impulse through the heart.
This is due to spreading of irregular
circus movement in many areas of
the heart.
2. In this case there is a
coordinated contraction
of heart takes place.
There is an incoordinated
contraction of heart
3. Heart rates are within
200 to 300 beats/min.
Heart rates are more than
300 beats/min.
66 VIVA IN MEDICAL PHYSIOLOGY
126. What are the clinical findings of ECG during MI?
a. Elevation of ST segments in the leads overlying the
area of infarct and
b. Depression of ST segment in the reciprocal leads.
127. What do you mean by Stokes-Adams syndrome?
In case of complete heart block, there is some delay
before ventricles start beating at their own rate. During
this period the systemic blood pressure falls to a very
low level and blood supply to brain becomes inadequate.
If ventricles do not beat for more than few seconds it
causes dizziness and fainting called as Stokes-Adams
syndrome.
128. What are the ECG changes during bundle branch
block? What changes take place in heart sound
production during its bundle branch block?
The ECG changes are as follows:
• Prolonged QRS complex (>0.12 sec)
• Abnormal ST segment and T wave.
• The second heart sound is splited.
129. What do you mean by extra-systole?
The spontaneous heart beat produced by the irritable
focus within heart under some abnormal condition is
known as extra-systole.
130. What types of ECG changes take place in atrial
flutter and atrial fibrillation?
In case of atrial flutter following changes are seen:
a. Shortening of all time intervals, e.g. PR, TP intervals
b. Merger of T wave with P wave of next cardiac cycle
c. 2nd degree type (2:1) of heart block.
In case of atrial fibrillation following changes are seen:
d. Absence of P wave.
e. Appearance of fibrillation (f) waves
f. Absence of T wave
g. Irregular QRS complex.
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131. How does the ECG record changes with time after
MI?
• Within few hours after MI: Elevation of ST segment.
• After some days of MI: Elevation of ST segment along
with inversion of T wave.
• After several weeks of MI: ST segments return to
normal but inversion of T wave is still present along
with appearance of Q wave.
• After months and years of MI: T wave becomes normal
and Q wave becomes deep.
132. What do you mean by mean circulatory filling
pressure and mean systemic filling pressure?
If the heart beat is stopped, the flow of blood every where
in the circulation ceases after few seconds resulting equal
pressure within the whole circulation which is known as
mean circulatory filling pressure.
Whereas the mean systemic filling pressure is the
pressure measured everywhere in the systemic circulation
after blood flow is stopped by the clamping of the large
blood vessels at the heart. Normally the amount of both
are almost equal.
133. Name different types of blood vessels in vascular
system with examples of each.
These are as follows:
a. Distensible (Windkessel) vessels—aorta, pulmonary
artery and their large branches.
b. Resistance vessels—arterioles, meta-arterioles
c. Exchange vessels—capillaries
d. Capacitance vessels—venules and venous
compartments
e. Shunt vessels—AV anastomoses.
134. Blood flow to the different body organs can be so
effectively regulated by only small chages in the
caliber of the arteries. How is it possible?
As resistance to blood flow is inversely proportional to
the 4th power of the radius (r) of arterioles,the small
68 VIVA IN MEDICAL PHYSIOLOGY
changes of radius can cause greater changes of
resistance to blood flow and thereby flow to the different
body organ.
135. What do you mean by critical closing pressure?
Extravascular tissues exert a small but definite pressure
on vessels and when the intra-luminal pressure falls below
this extra-vascular pressure the vessel collapses. The
pressure at which the flow ceases is called as critical
closing pressure.
136. State the law of Laplace. What is its functional
significance?
It states that the distending pressure (P) in a distensible
hollow object is equal at equilibrium to the tension in the
wall (T) divided by two principal radii of curvature of object
(R1 and R2), i.e. P = T (1/R1+1/R2).
Significance: (i) smaller the radius of the blood vessels
lesser the tension in the wall necessary to balance the
distending pressure. This is why (i) thin and delicate
capillaries are less prone to rupture, (ii) dilated heart has
to do more work than normal heart.
137. What is axon reflex?
In response to a firm stroke in the skin the afferent
impulses are relayed to the endings near cutaneous
arterioles down the branches of sensory nerve to result
cutaneous arteriolar dilatation. This neural pathway which
does not involve CNS is known as axon reflex.
138. What do you mean by cold blue skin and warm red
skin?
Cold blue skin is the skin in which the arterioles are
constricted and the capillaries are dilated whereas in warm
red skin both arterioles and capillaries are dilated.
139. What is tripple response?
A firm and strong stroke on the skin by a blunt object
evokes a series of responses which are
(i) Red reaction
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CARDIOVASCULAR SYSTEM 69
(ii) Flare and
(iii) Wheal.
These responses to the injury are collectively known
as tripple response.
140. What is the physiological basis of red reaction, flare
and wheal?
Red reaction: It is due to the dilatation of precapillary
sphincter due to release of histamine and/or bradykinin
like vasodilator substances.
Flare: It is due to dilatation of arterioles, terminal arterioles
and precapillary sphincter which causes increase in blood
flow and thereby irregular erythematous area surrounding
the red line.
Wheal: It is due to increased capillary permeability and
rise of capillary pressure which ultimately causes local
diffuse swelling at and near the site.
141. What is white reaction?
When a pointed object is drawn lightly over the skin the
stroke line becomes pale due to draining out of blood
from the capillaries and small vein due to contraction of
precapillary sphincters.
142. What is the average total peripheral resistance of
rest?
It is 1 PRU.
143. On what factors the peripheral resistance does
depend.
It depends on the elasticity of vessel wall, diameter of
arterioles (inversly), viscosity and velocity of blood
directly.
144. Define Poiseuille’s law.
It states that resistances to blood flow in a blood vessel
proportionately varies with length of blood vessels and
viscosity of blood and inversely with 4th power of radius
of lumen of vessels.
70 VIVA IN MEDICAL PHYSIOLOGY
145. What is circulation time? Give the value of total
circulation time.
It is time taken by blood to flow from one site to any other
specific site. Normal total circulation time is 12-16 sec.
146. Coronary blood flow fluctuates with each phases
of cardiac cycle, explain.
During systole the coronary blood flow is reduced because
of compression of coronary vessels due to contraction
of cardiac muscle whereas during diastole as cardiac
muscle relaxes, there is distention of coronary vessels to
its original diameter and thus blood flow through it to heart
muscle is increased.
147. Why does the subendocardial portion of left
ventricle is more prone for MI?
It is for two reasons as follows:
a. No blood flows to this portion during systole because
of poor blood supply in this region and also
compression of blood vessels during systole.
b. Anaerobic respiration goes on in inner layer which
increases further under stress.
148. What is the normal time taken for coronary
circulation?
It is about 8 sec.
149. What are the factors on which coronary blood flow
depends?
These are mainly lumen of coronary vessels, mean aortic
pressure and also by cardiac output, HR, body
temperature, CO2 concentration in blood and cardiac
sympathetic stimulation.
150. What is normal pulmonary blood flow rate?
It is about 3-5 lit/min.
151. What is the normal blood flow rate in liver?
It is about 1500 ml/min.
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152. What is the normal coronary blood flow?
It is about 225 ml/min.
153. Give the normal value of cerebral blood flow.
It is approx. 750 ml/min.
154. Define shock. Classify it.
Shock is a syndrome characterised by low cardiac output
which is inadequate to maintain normal tissue perfusion.
It is of 4 types—hypovolemic, vasogenic, cardiogenic and
obstructive shock.
155. What do you mean by cold shock?
When the amount of fluid in the vascular system is
inadequate to fill it, resulting in decrease in circulatory
blood volume it is known as hypovolemic or cold shock.
156. What is warm shock?
When the diameter of capacitance vessels is increased
by vasodilatation, there is a decrease of cardiac output
inspite of normal blood volume. This type of shock is
vasogenic shock and in this type of shock as skin
becomes warm it is also called as warm shock.
157. What is congested shock?
The cardiogenic shock causes congestion of lungs,
viscera and that is why it is called as congested shock.
158. What is Bezold-Jarish reflex?
The Ventricular receptors are sensitive to chemicals or
partial occlusion of aorta or coronary artery which are
responsible for profound bradycardia, hypotension and
apnoea. This response is known as ‘Coronary chemo
reflex’ or Bezold Jarish reflex which is clinically
associated with Myocardial infarction or vaso-vagal
syncope.
159. What is sinus arrhythmia?
During inspiration HR is increased and during expiration
HR is reduced. This phenomenon is called as sinus
arrhythmia.
72 VIVA IN MEDICAL PHYSIOLOGY
160. What is bradycardia? Where can you see the
physiological bradycardia?
Decrease of heart rate below 60 beat/min is known as
bradycardia which is physiologically seen in following
conditions.
• Athelets
• Males
• Emotional stimuli like shock, grief, depression, etc.
• During expiration.
161. What do you mean by laminar and turbulent flow?
How does turbulence produce?
a) Laminar or stream line flow: It is fixed layer wise i.e.
each layer of blood remains at the same distance from
the wall blood vessels flowing through a long vessel
and the velocity of blood is maximum in the core of
the blood vessels and minimum in it’s periphery or
surface. This type of steady rate of blood flow is known
as laminar blood flow.
b) Turbulent blood flow: When the blood flows crosswise
in the vessels by forming whorls in the blood is called
as eddy current. This type of blood flow is known as
turbulent blood flow. It is produced by obstruction
of vessels or when it takes sharp U turn.
162. What are the signs and symptoms of Shock?
Different signs and symptoms manifested during shock
are as follows:
• Reduction in arterial blood pressure.
• Reflex tachycardia and reduced stroke volume.
• Decrease in pulse pressure and appearance of
thready pulse.
• Reduction in velocity of blood flow producing stagnant
hypoxia and cyanosis.
• Pale and cold skin due to reflex vasoconstriction.
• Decreased urinary output due to reduced renal blood
flow and GFR.
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•
•
•
•
CARDIOVASCULAR SYSTEM 73
Fainting due to reduced blood flow to the brain tissue.
Feeling of intense thirst if the patient is conscious.
Rapid and shallow breathing.
Metabolic acidosis due to excessive production of
lactic acid by myocardium.
Death due to cerebral or cardiac failure.
163. What are the symptoms of left ventricular failure?
These are:
a. Difficulty in breathing on exertion.
b. Dyspnoeic attack at night.
c. Dyspnoea in supine position.
164. What are signs and symptoms of right ventricular
failure?
These are:
a. Engorgement of right atrium
b. Increased venous pressure
c. Swelling of liver
d. Peritoneal and pleural effusion.
e. Cyanosis and dyspnoea.
f. Edema.
165. What are the common causes of left ventricular
failure?
These are: essential hypertension, coronary insufficiency,
myocardial fibrosis and mitral valve incompetence.
166. What are the salient features of left ventricular
failure?
These are:
a. Decrease in cardiac output with vasoconstriction of
peripheral vessels
b. Pulmonary edema, dyspnoea and anoxia (cardiac
asthma)
167. How do you differentiate left and right cardiac
failure broadly on the basis of edema?
In left heart failure, pulmonary edema is seen whereas in
right heart failure, edema is systemic in nature.
74 VIVA IN MEDICAL PHYSIOLOGY
168. Enumerate some of the effects of severe
hemorrhage.
These are decreased blood volume, state of shock,
increased heart rate, decreased systolic BP,
vasoconstriction, hemo-dilution, rapid and shallow
breathing, blurred vision, fainting, etc.
GI SYSTEM AND METABOLISM 75
SECTION I : THEORY VIVA
1.4
Gl System and Metabolism
1. Name the different layers in cross-section of GIT.
These are—serous layer, longitudinal and circular smooth
muscular layer, submucous layer and mucous layer.
2. Enumerate the intrinsic innervation of GIT.
Intrinsic innervation is divided into two types as follows:
a. Myenteric or Auerbach’s plexus—present between
longitudinal and circular muscle layer. It is mainly
motor in function.
b. Submucous or Meissner’s plexus—lies between
submucous and inner circular muscle layer. It is mainly
sensory in function.
3. Define villi.
Mucosal surface of duodenum and small intestine shows
finger like projections to provide greater surface area for
absorption. These finger like projections are called as
villi.
4. What is glycocalyx? What is its function?
On the luminal surface, the brush border of GI tract is
lined by an amorphous layer called glycocalyx. It has a
protective function.
5. What is crypts of Lieberkühn? What are the
component cells of it?
Between the villi of intestines there are some simple
tubular glands lined by low columnar epithelium. These
are known as crypts of Lieberkühn. It contains:
76 VIVA IN MEDICAL PHYSIOLOGY
a. Goblet cells—secrete mucous.
b. Argentaffin cells—Secrete secretin and 5 HT.
c. Paneth cells—Along with epithelial cells these secrete
enzymes responsible for digestion.
6. What are Brunner’s glands? What is its function?
In duodenum, there are some special submucosal glands
which are tortuous, long and resemble gastric pyloric
glands. These submucosal glands are known as
Brunner’s glands.
In response to fatty food and secretin, it produces a
large volume of thick alkaline mucosa responsible for
protection of duodenal mucosa from gastric acid.
7. What is Peyer’s patch?
The aggregated lymphatic follicles seen in ileum are
known as Peyer’s patch.
8. What is taenia coli?
The longitudinal smooth muscle layer is not equally
distributed throughout the gut wall but is collected into 3
distinct bands in large intestine. These bands are called
taenia coli.
9. Name the salivary glands. What are the constituent
cells of each gland?
There are 3 pairs of salivary glands named:
a) Parotid gland—constitutes serous cells only.
b) Submandibular gland—contains both serous and
mucous cells though serous cells are more in number.
c) Sublingual gland—constitutes mainly mucous and
partly serous cells.
10. What are the actions of parasympathetic and
sympathetic nerve stimulation on salivary gland?
Parasympathetics are secretomotor in function and
sympathetic fibers are vasoconstrictor.
11. What is ptyalin? State its functions.
Ptyalin is a digestive enzyme present in saliva secreted
by serous cells of salivary gland. When activated it
converts unboiled starch to maltose.
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GI SYSTEM AND METABOLISM 77
12. What is mucin? What are its functions?
It is secretory product of mucous cells of salivary gland.
It has following functions:
a. It lubricates the food
b. It protects oral mucosa.
c. It aids speech by facilitating the movements of lips
and tongue.
13. Is salivation a secretory or an excretory process?
It is a secretory process.
14. What do you mean by primary and secondary
salivary secretions?
The acinar cells of salivary glands secrete K+and HCO3¯
and also Cl¯ along with sufficient water into the acinal
lumen making the secretion isotonic. This secretion is
known as primary secretion. When these acinar cell
secretions pass through salivary duct the salivary duct
cells actively absorb K+ and an accompanying anion
making the previous secretion hypotonic. These final
secretory products are known as secondary salivary
secretion.
15. What is xerostomia? What is due to?
The suppression of salivary secretion is known as
xerostomia or aptyalism. It is due to:
a. Anxiety, fear, fever and dehydration.
b. Obstruction of salivary duct due to calculus.
16. What is Sialorrhoea?
The state of hypersecretion of saliva is known as
sialorrhoea seen in pregnancy, parkinsonism,
schizophrenia, etc.
17. What are the different muscles of mastication?
These are masseter, temporalis, internal and external
pterygoid and buccinator.
18. What are the role of teeth in mastication?
Different teeth helps in mastication for example:
• Incisors provide strong cutting action.
78 VIVA IN MEDICAL PHYSIOLOGY
•
•
Canines helps in tearing action.
Premolars and molars have grinding action.
19. How saliva prevents the formation of dental carries?
It decreases the risk of buccal infection and dental caries
and thus maintain oral hygiene by:
• Continuous secretion of saliva that washes away food
debris and pathogenic bacteria.
• The enzymes lysozyme and thiocyanate kill some
bacteria like Staphylococcus, Streptococcus and
Brucella.
• The protein antibodies which destroy bacteria
including the bacteria causing dental carries.
20. What are different stages of deglutition?
These are oral stage, pharyngeal stage and oesophageal
stage.
21. What is deglutition apnoea?
During pharyngeal stage of deglutition process once the
deglutition reflex is initiated there is a elevation of larynx
along with hyoid bone and also approximation of vocal
cords. This event ultimately causes stoppage of breathing
known as deglutition apnoea.
22. Where is the deglutition centre located?
It is in medulla oblongata.
23. What is dysphagia?
It is the difficulty in swallowing.
24. What do you mean by aerophagia? What is its
cause?
Aerophagia is a state of increase intake of air through
mouth. It occurs in nervous individuals whose upper
esophageal sphincter tone is low. So air is unavoidably
swallowed in the process of eating and drinking.
25. What is Achalasia cardia? What is its relation with
dysphagia?
It is the state of failure of lower esophageal sphincter to
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GI SYSTEM AND METABOLISM 79
relax (due to excessive tone of LES) completely during
swallowing → Leads distension of esophagus which is
clinically known as Achalasia or megaesophagus. As it
causes in difficulty in exit of food to stomach during
swallowing it results dysphagia.
26. What do you mean by Gastroesophagial reflux? Why
it is associated with heart burn?
Any abnormality in closing the LES due to incompetence
of LES causes efflux of acid pepsin mixed chyme from
stomach to the oesophagus, which is known as gastro
oesophageal reflux. In this situation the acid pepsin
mixed chyme enters the esophagus the wall of which is
not resistant enough to that of stomach wall → leads
ulceration of oesophageal mucosa →results epigastic
burning sensation (clinically known as ‘Heart burn).
27. Name different gastric glands and their secretions.
There are three types of gastric glands as follows:
• Main gastric gland: It is found in mucosa of body and
fundus of stomach. It contains 3 cells:
a. Parietal (oxyntic) cell—secretes HCl and intrinsic
factor.
b. Chief or peptic cell—secretes pepsinogen.
c. Surface epithelial cell—secretes visible mucous.
• Cardiac tubular gland: It secretes soluble mucous
• Pyloric or antral gland contains:
i. Surface epithelial cells—secrete soluble mucous.
ii. G cells—secrete gastrin.
28. What do you mean by APUD cells?
Some specialised cells present in brain and also in GIT
are capable of amine precursor uptake and
decarboxylation, which are known as APUD cells. G cells,
S cells present in GIT are the examples of APUD cells.
29. Mention the factors increasing gastrin release.
They are as follows:
a) Luminal factors: These are the products of protein
digestion and distension of pyrolic antrum.
80 VIVA IN MEDICAL PHYSIOLOGY
b) Neural factors: Vagal stimulation
c) Blood-borne factors like calcium, epinephrine, etc.
30. What do you mean by post-prandial alkaline tide?
When gastric acid secretion is increased after meal,
sufficient amount of H+ is secreted to raise HCO3¯
concentration in the gastric venous blood which
contributes a greater amount of HCO3¯to the systemic
circulation and pH of systemic blood increases. This
condition is known as post-prandial alkaline tide.
31. Name the phases of gastric secretion.
These are cephalic phase, gastric phase and intestinal
phase.
32. What do you mean by appetite juice?
In response to psychic stimuli by taste, sight, smell of
food there is a reflex stimulation of vagus nerve which in
turn increases gastric secretion known as appetite juice.
33. What do you mean by Pavlov’s pouch (Fig. 1.4.1)?
What is its significance?
In an experiment, Pavlov surgically separated a small
portion of stomach with intact nerve and blood supply
from the main body of stomach to prevent the entry of
food into that small separated sac like structure. This is
known as Pavlov’s pouch as represented by Figure
1.4.2A. In this type of experimentation on dog, stimulation
of vagus nerve causes a flow of gastric juice rich in HCl
and pepsin from the both part (main body and Pavlov’s
pouch) of stomach but it can be collected in a pure form
from (without mixing with food) Pavlov’s pouch only. This
proves that vagus has secretomotor function on stomach.
34. What do you mean by Sham feeding?
In another experiment, the esophagus is divided in the
neck region of a dog and two ends are brought separately
to the surface and satured in position. In this case, animal
can eat for hours without satisfying its appetite as the
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GI SYSTEM AND METABOLISM 81
Fig. 1.4.1: Pavlov’s pouch
swallowed food never reach to the stomach but falls out
through the neck opening. This type of feeding is known
as Sham feeding as represented by Figure 1.4.2.
Figs 1.4.2A and B: Sham feeding. (A) represents the opening of the
divided oesophagus and (B) is the body of stomach with fistula
35. What is receptive relaxation?
When food enters into the stomach, it relaxes by a reflex
process to accommodate food further. This reflex
relaxation of stomach is called as receptive relaxation.
36. What do you mean by gastric (antral) pumps?
The peristaltic wave provides a pumping action in the
antral or pyloric region of the stomach which results
82 VIVA IN MEDICAL PHYSIOLOGY
gastric emptying. This pumping action is called as antral
or pyloric or gastric pumps.
37. What is enterogastric reflex?
The products of protein digestion and acid in duodenum
reflexly decrease gastric emptying. This neurally mediated
reflex is known as enterogastric reflex.
38. How does the gastric emptying associate with type
of food ingested?
It depends on the basis of type of food as follows:
• Carbohydrate rich food—results rapid gastric
emptying.
• Protein rich food—results slow gastric emptying.
• Fat rich food—results slowest gastric emptying.
39. What do you mean by hunger contraction? What is
its significance?
In empty condition ordinarily there is no peristaltic wave
but at intervals of one or two hours a powerful peristaltic
wave develops in the antral region which ultimately
reaches the end of the ileum. As these contractions are
associated with pangs of hunger it is known as hunger
contraction. This results the driving out of remnant food
from stomach to small intestine.
40. Name different gastric function tests.
These are:
• Histamine test
• Fractional test meal
• Augmented histamine test
• Barium meal X-ray
• Endoscopy and biopsy.
41. What is achlorhydria? Why it is often associated
with pernicious anaemia?
The complete failure of gastric acid secretion due to
atrophy or degeneration of gastric mucosa is known as
achlorhydria.
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GI SYSTEM AND METABOLISM 83
HCl and intrinsic factors are secreted by same cell of
gastric mucosa and intrinsic factor is responsible for vit
B12 absorption from food which in turn increases RBC
formation. Due to atrophy or degeneration of gastric
mucosa, intrinsic factor is also not secreted. So the
achlorhydria is thus associated with pernicious anemia.
42. What is dumping syndrome?
A condition characterised by development of weakness,
dizziness and sweating after meal is known as dumping
syndrome.
43. Define peptic ulcer. What are its causes?
Peptic ulcer is referred as the breakdown of the mucosal
epithelium of the stomach and of duodenum. Causes are:
• H. pylori infection
• Use of NSAID
• Zollinger-Ellison syndrome
• Increase in gastric secretion
• Mental and physical stress.
44. What is false and true achlorhydria?
Sometimes the stomach secretes acid but it is not detected
as it gets neutralised by the test meal. This is called as
false achlorhydria. Whereas true achlorhydria is the
condition when stomach does not secrete any acid at all.
45. Define vomiting. What is the vomiting center.
Vomiting is an act of expulsion of gastric contents by
regurgitation through the esophagus and oral cavity.
The vomiting centre is the chemosensitive trigger zone
(CTZ) located in or near the area postremas on medullary
surface.
46. Which portion of pancreas subserves the exocrine
function?
It is compound alveolar tissues containing secretory acini
and duct cells.
84 VIVA IN MEDICAL PHYSIOLOGY
47. Which hormones are responsible for pancreatic
secretion? What are their roles?
Generally two hormones—secretin and cholecystokininpancreozymin (CCK-PZ). Secretin increases the alkaline
watery pancreatic juice secretion whereas CCK-PZ
increases pancreatic secretion rich in enzyme.
48. Mention the substances synthesised by liver.
These are:
i. Plasma proteins
ii. Clotting factors like fibrinogen, prothrombin, factor
V, VII, IX, and X
iii. Enzymes like SGOT, SGPT and alkaline
phosphatase
iv. Urea
v. Cholesterol.
49. What is bile? Differentiate between liver and
gallbladder bile.
Bile is the secretory product of hepatic cells that helps in
digestion and absorption of fatty foods specially.
Parameter
Liver bile
Gallbladder bile
Colour
Consistency
Water
Bile salts
Bile pigments
Light golden yellow
Like water
97%
Less (120-180 mg%)
Less
Almost black
Thicker
89%
More (5 to 6 times)
More
pH
7.3-7.7
7.0-7.2
50. What do you mean by primary and secondary bile
acids?
The cholic acid and chenodeoxycholic acid produced in
liver from cholesterol are known as primary bile acids.
When these are exposed to colon they are converted to
deoxycholic acid and lithocholic acid by colonic bacteria
which are known as secondary bile acids.
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GI SYSTEM AND METABOLISM 85
51. Define bile salts. Give examples.
Sodium and potassium salts of bile acids are known as
bile salts. These are Na+/K+- glycocholate or taurocholate.
52. What do you mean by enterohepatic circulation?
Of the total bile salts entering into the duodenum 90-95
percent are reabsorbed actively from the terminal ileum in
the portal vein and return to the liver to be excreted again.
This cyclical passage of bile salts from liver to intestine
and then back to liver is known as enterohepatic circulation.
53. Name the different bile pigments and their origin.
Bilirubin and biliverdin. They are formed from globin
portion of hemoglobin after the destruction of old RBCs
by RE cells. 1gm Hb produces 40 mg of bilirubin.
54. What do you mean by cholerectic and cholago-gues?
• Cholerectic are substances which increase biliary
secretion from the liver, e.g. bile salts and bile acids.
• Cholagogues are the substances that cause
contraction of gallbladder, e.g. fatty acids, Ca++, etc.
55. What is cholelithiasis? What are the types of
gallstone?
Presence of stones in the gallbladder or bile ducts is
called as cholelithiasis.
Gallstones are of two types:
a. Cholesterol stones—These are radioluscent.
b. Pigment stone (Calcium bilirubinate)—These are
radioopaque.
56. Give normal value of A:G ratio. In which condition
it is reversed?
Normal value is 1.7:1. It is reversed in hepatic
insufficiency.
57. Mention some liver function tests.
i. Galactose tolerance test
ii. Estimation of SGOT, SGPT and alkaline
phosphatase
86 VIVA IN MEDICAL PHYSIOLOGY
iii. Estimation of total bilirubin
iv. Hippuric acid excretion test
v. Ultrasound scan and CT scan.
58. What is Jaundice?
It is the clinical condition characterised by yellowish
pigmentation of the skin, mucous membrane and deeper
tissues due to presence of more than 2 mg% serum bilirubin.
59. Mention the differences between hemolytic and
obstructive jaundice.
Parameters
Hemolytic jaundice
Obstructive jaundice
Cause
Excessive breakdown
of RBC
High (unconjugated)
Normal
Obstruction of bile ducts.
Normal
Present
Normal
Absent
Absent
Present
Increases
Excessive yellow
Normal
Indirect positive
Absent
Clay coloured
Increased
Direct positive
Normal
Mildly impaired
Serum bilirubin
Serum alkaline
phosphatase
A: G ratio
Hemorrhagic
tendency
Urinary bilirubin
Urinary
urobilinogen
Faecal colour
Faecal fat
Van Den Bergh test
Liver function test
High (conjugated)
High
60. What do you mean by succus entericus?
The secretion of the crypts of Lieberkühn in the small
intestine is known as intestinal juices or succus entericus.
61. What do you mean by intestinal adaptation? What
is due to?
Removal of short segment of small intestine (jejunum or
ileum) leads to compensatory hypertrophy and
hyperplasia of the remaining mucosa with gradual return
of normal absorption. This is known as intestinal
adaptation. It is due to:
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GI SYSTEM AND METABOLISM 87
Direct effect of nutrients in the intestinal lumen on the
mucosa.
GI hormonal influence on the intestinal mucosa.
62. Enumerate in brief the movements of small
intestine.
In small intestine, two types of contractions are seen as
follows:
a) Rhythmic segmental contraction—by this movement
food is segmented and mixed together with digestive
juices.
b) Peristalsis—it propels the intestinal contents towards
the ileo-caecal valve.
63. What is ‘law of the gut’?
The peristaltic movement once initiated in response to
food is bidirectional but it normally dies out rapidly in oral
direction while continuing towards aboral direction for
considerable distance. This property is known as polarity
of the intestine or ’law of the gut’
64. What is peristaltic rush? Why does pain sensation
associates with peristaltic rush?
Localised mechanical obstruction of small intestine
initiates very tense peristaltic waves called peristaltic rush
which causes severe cramping pain. This pain is due to:
• Compression of blood vessels in its wall producing
local ischemia.
• Stimulate visceral afferent nerve fibers to cause
sweating, hypotension and severe vomiting.
65. What is gastro-ileal reflex?
When food leaves the stomach the caecum relaxes and
passage of chyme through the ileo-caecal valve
increases.This is called as gastroileal reflex.
66. What is mass peristalsis?
These are the simultaneous contractions of the smooth
muscle occurring at the same time over a large portion
of the colon.
88 VIVA IN MEDICAL PHYSIOLOGY
67. What is gastrocolic reflex?
Distension of the stomach by the food initiates
contractions of the rectum resulting a frequent desire to
defecate. This reflex is called as gastrocolic reflex.
68. What is diarrhoea? Why does it may result even
death?
Increase frequency of passage of stools is called as
diarrhoea. In severe cases, it may even cause death
because of shock, i.e. cardiovascular collapse resulted
due to loss of large amount of electrolytes like Na+, K+
and water.
69. Name two colonic bacteria. Give its two functions.
These are Escherichia coli and Enterobactor. Its useful
functions are as follows:
i. It synthesises vit K, B complex and folic acid.
ii. It helps in metabolism of bile pigments.
70. What are the digestive enzymes present in gastric
juice?
These are pepsinogen, lipase and renin.
71. Enumerate the function of pepsin, HCl and renin:
• Pepsin—It converts protein into peptones and
proteases by the help of HCl
• HCl• It kills the bacteria present in food.
• It hydrolyses food and helps in digestion.
• It activates pepsinogen to form pepsin.
• It also helps in iron and Ca2+ absorption.
• Renin—It curdles the milk and converts caseinogen
into calcium paracaseinate.
72. What are the functions of villikinins and
cholecystokinin?
Villikinin secreted by duodenal mucosa helps to stimulate
villi movements whereas CCK liberated by duodenal
mucosa stimulates contraction of gallbladder.
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GI SYSTEM AND METABOLISM 89
73. What are the digestive enzymes of pancreatic
juice? Mention their function.
These are trypsinogen, chymotrypsinogen, amylase and
lipase.
• Trypsinogen—Once activated by enterokinase it
activates chymotrypsinogen to chymotrypsin.
• Chymotrypsinogen—Once activated it converts
peptones into dipeptide stage.
• Amylase—It converts starch into maltose.
• Lipase—It converts fat into fatty acids and glycerols.
74. Name the various enzymes present in succus
entericus. Mention each of their function.
These are erepsin, nuclease, nucleotidase, arginase,
sucrase, maltase and lactase.
• Erepsin—It converts simple peptides into amino acids.
• Nuclease (Nucleosidase and nucleotidase)—These
are responsible for digestion of nucleoproteins.
• Arginase—It converts arginine to urea and ornithine.
• Sucrase—Splits sucrose into fructose and glucose.
• Maltase—Converts maltose to 2 molecules of
glucose.
• Lactase—Lactase converts lactose to glucose and
galactose.
75. What is steatorrhoea?
Inflammation of pancreatic acinar cell due to any cause
destroys the acinar and ductular cell resulting deficient
secretion of pancreatic juice. This condition results low
digestion of fatty food due to absence of activation of
lipase →increased fat or oil in the stool which is known
as steatorrhoea.
76. What are the main sources of energy in man?
They are of two types:
• High energy phosphate—like ATP, ADP, creatinine
phosphate, acetylphosphate.
• Low energy phosphate—like glucose-1–phosphate,
glucose-6-phosphate, etc.
90 VIVA IN MEDICAL PHYSIOLOGY
77. Define calorie and joule.
A calorie is the amount of heat required to raise the
temperature of 1 kg of water from 15°C to 16°C. This
large calorie is equivalent to 1000 small calories.
Joule is defined as the energy expressed when one
kilogram of substance moved through one meter by 1
newton, i.e. a force which accelerate 1kg by 1m/sec2.
78.
•
•
•
What is the potential energy of various foods?
1 gm of carbohydrate evolves 4.1 cal heat.
1 gm of protein evolves 4.1 cal of heat.
1 gm of fat evolves 9.3 cal of heat.
79. Define BMR. How does it express?
BMR is the amount of heat produced in the body in a
given time in complete physical and mental resting state
at 20°C room temperature. It is expressed as calories/
sqm body surface area/hour. Normal value is 40 cal/sqm/
hr.
80. Name some conditions when BMR varies.
• Increase of BMR:
• Physiological conditions—muscular activity, cold
weather, food intake, tension, etc.
• Pathological conditions—hyperthyroidism, fever,
anaemia, etc.
• Decrease of BMR:
• Physiological condition—Starvation, undernutrition
• Pathological condition—hypothyroidism, adrenal
cortex deficiency, hypothermia, etc.
81. What is the main source of energy of following
tissue/organ?
• Skeletal muscle
glucose.
• Cardiac muscle
lactic acid.
• Brain
blood glucose.
RESPIRATORY SYSTEM 91
SECTION I : THEORY VIVA
1.5
Respiratory System
1. What do you mean by external and internal
respiration?
The absorption of O2 and removal of CO2 from the body
through lungs is known as external respiration. Whereas
the utilisation of O2 and production of CO2 by the cells at
the cellular level is known as internal respiration.
2. What do you mean by conducting zone and
respiratory zone?
The portion of the respiratory tract (i.e. upto 16th
generation as per Weibel's lung model) where no
exchange of gases takes place is known as conduction
zone whereas the portion of respiratory tract (i.e. beyond
16th generation) where gaseous exchange takes place
is known as respiratory zone which includes respiratory
bronchioles, alveolar ducts and the alveoli.
3. What is partial pressure? What are the partial
pressure of following gases?
The pressure exerted by any one gas in a mixture of
gases is called its partial pressure. The partial pressure
of different gases are as follows: O2—20.98 per cent;
CO2—0.03 per cent, N2—78.06 per cent.
4. If the percentage of O2 in inspired air is 20.98 per cent
then what will be the PO2 at sea level?
PO2 = per cent of gas/100 × total atmospheric pressure
= 20.98/100 × 760 mm Hg (at sea level)
= 159.5 mm Hg.
92 VIVA IN MEDICAL PHYSIOLOGY
5. What is Dalton's law?
It states that total pressure exerted by a mixture of gases
is equal to the sum of the partial pressures of all the
gases present within it.
6. What is Henry's law?
It states that if temperature is kept constant, amount of
gas dissolved in any solution is directly proportional to
the partial pressure of that gas.
7. What do you mean by 'Pump Handle' movement and
'Bucket Handle' movement in relation to
respiration?
During inspiration the upper ribs, i.e. 2nd to 6th ribs move
upward to assume more horizontal position to increase
anteroposterior diameter of the chest. This type of
movement of upper ribs is called as 'Pump Handle
movement'. On the other hand during inspiration the lower
ribs (i.e. 7th to 10th) swing outward and upward to
increase the transverse diameter of the chest like a
bucket handle and therefore is known as 'Bucket Handle"
movement.
8. Give the normal value of intrapulmonary or intraalveolar pressure.
It is about 760 mm Hg.
9. Why intra-alveolar pressure is equal to that of
atmospheric pressure? How is it affected during
inspiration and expiration?
It is equal to the atmospheric pressure as during quiet
breathing, at the end of expiration and at the end of
inspiration, no air is going in and out of the lungs.
During inspiration it decreases 3 mm Hg below its
normal value, i.e. 757 mm Hg and during expiration it
increases 3 mm Hg above its normal value, i.e. 763
mm Hg.
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RESPIRATORY SYSTEM 93
10. What is Valsalva manoeuvre and Muller's
manoeuvre?
Forced expiration against a closed glottis may produce
positive intrapulmonary pressure of > 100 mm Hg above
the atmospheric value. This voluntary act is known as
Valsalva manoeuvre.
Forced inspiration against closed glottis can reduce
the intrapulmonary pressure to < 80 mm Hg below the
atmospheric value. This voluntary act to reduce the intrapulmonary pressure is known as Muller's manoeuvre.
11. What is intrapleural pressure? How does it varry
during inspiration and expiration? Why normally it
is negative?
It is the pressure within the pleural cavity around the
lungs. Normal value is -2.5 mm Hg. During inspiration it
decreases further to -7.5 mm Hg and during expiration it
increases to 2.5 mm Hg. It is normally negative because
of following factors:
i. The lung tries to collapse because of its elasticity
(elastic recoil) and surface tension in the alveoli.
ii. The chest wall always tries to expand.
Therefore the two pleural layers become subjected to
a force that tries to separate them resulting a suction
pressure or negative pressure.
12. Name the muscles of inspiration and expiration.
a) Muscles during normal breathing:
i. Diaphragm
ii. External intercostal muscles.
b) Muscles during forceful breathing:
• Inspiratory muscles : Along with the muscles described
above there are other muscles termed as accessory
inspiratory muscles responsible for forceful inspiration.
These are:
• Sternocleidomastoid - lifts the sternum upward.
• Serratus anterior - lifts many ribs.
• Scalene - lifts 1st two ribs.
94 VIVA IN MEDICAL PHYSIOLOGY
•
Expiratory muscles:
• Internal intercostal muscles
• Abdominal muscles: These include abdominal recti,
transverse abdominis, internal oblique.
13. Why the 'Wheeze' sound is heard during expiration
but not in inspiration of an asthma patient?
During inspiration the intrapleural and mediastinal
negativity rises and as a result the bronchial diameter
increases. Reverse occurs during expiration. Therefore
resistance to airflow is normally low in inspiration and
high in expiration. This is why in bronchial asthma
inspiration may not be difficult but expiration becomes
difficult. This explains why the "Whezze" in bronchial
asthma is heard during expiration but not in inspiration.
14. Define and give the normal value of TV, IRV, ERV
and EV.
• Tidal volume (TV): It is the amount of air breathed in
or out of lungs during quiet respiration. Normal value
is 500-800 ml.
• Inspiratory reserve volume (IRV): It is the maximum
amount of air that can be inspired from the end
inspiratory position by forceful and maximal activity.
Its normal value is 2000-3200 ml.
• Expiratory reserve volume (ERV): It is the maximum
amount of air that can be expired by maximum forcible
effort from the end of normal expiratory position.
Normally its value is 750-1000 ml.
• Residual volume (RV): It is the volume of air which
remains in lungs even after forceful expiration. Normal
value =1200 ml.
15. Define and give the normal value of IC, FRC and
TLC.
• Inspiratory capacity (IC): It is the maximum amount of
air that can be inspired from the end expiratory
position. Normal value: 2500-3700 ml.
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Functional residual capacity (FRC): It is the amount
of air contained in the lungs at end expiratory position.
Normal value is 2500 ml.
Total lung capacity: It is the volume of air retained by
the lungs after a maximal inspiration. Normal value is
6 lits.
16. Define vital capacity. What is its importance?
It is the maximum volume of air which can be expired by
forceful effort after a maximal inspiration.
It provides useful information about the strength of
respiratory muscles and also provides useful information
about other aspects of pulmonary function through FEV1.
17. In which posture VC is highest and why?
In standing posture it is the highest as in standing position
diaphragm descends down increases intrathoracic volume
increases intra-alveolar volume increases inspiration.
18. Why does VC decrease during pregnancy?
During pregnancy diaphragm is pushed up by the growing
foetus resulting decrease of intra-thoracic volume and
thereby decrease of capacity to inspire air and there by
VC is decreased.
19. Name two methods for measuring FRC.
It is nitrogen wash out method and helium dilution method.
20. What is the significance of FRC?
These are:
• It maintains the RV constant.
• It acts as a buffer and allows continuous exchange of
gases to occur even during expiration, thereby
prevents sudden changes in partial pressure of gases
in the blood.
21. What are the factors affecting FRC?
These are: Old age, emphysema, bronchial asthma,
atelectasis.
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22. Define timed vital capacity.
The maximum volume of air which can be breathed out
as forcibly and rapidly as possible after deepest
inspiration is known as vital capacity. If this VC is recorded
in relation to time, it is known as timed vital capacity.
23. What is the significance of FEV1 or Ist second of
timed vital capacity?
It helps to distinguish between restrictive and obstructive
lung diseases. In restrictive lung diseases like
kyphoscoliosis and ankylosing spondylitis vital capacity
decreases but FEV 1 remains normal whereas in
obstructive diseases like emphysema and bronchial
asthma vital capacity remains normal but FEV 1
decreases.
24. What is pulmonary ventilation?
It is the amount of air breathed in or out in one minute. It
is computed as TV × RR/min where RR represents
respiratory rate.
25. What is maximum breathing capacity?
It is the largest amount of air that can be breathed in or
out in one minute by maximum voluntary efforts. It is
computed as VC × RR/ min = 100 L/min.
26. Define pulmonary reserve or breathing reserve.
It is the maximum amount of air above the pulmonary
ventilation which can be breathed in and out in each
minute. It can be computed as MVV-PV (PV represents
pulmonary ventilation).
27. What is the dyspnoeic index? What value marks
the presence of dyspnoea?
When the pulmonary reserve is expressed as percentage
of MVV it is known as pulmonary reserve or dyspnoeic
index (DI). It is computed as (MVV-PV) × 100/ MVV; normal
value is > 60-70 per cent.
If this value becomes less than 60 per cent then
dyspnoea may be present.
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28. What do you mean by lung surfactant? What do you
mean by hyalin membrane disease?
Lung surfactant is a mixture of protein-lipid complexes
made up of mainly dipalmitoyl phosphatyl choline,
secreted by type II alveolar epithelial cells, which reduces
the surface tension of the fluid linning of the alveoli.
Due to deficiency of surfactant in this disease the surface
tension in the lungs of these newborn babies is very high
making the expansion of the lungs very difficult. This may
cause the death of that infant due to pulmonary
insufficiency. This disease is known as respiratory
distress syndrome or hyalin membrane disease.
29. State Hook's law in relation to lung.
Length is directly proportional to force within a
physiological limit.
30. Define lung compliance. What is 'hysteresis' curve
of lung compliance?
The change of lung volume per unit change in airway
pressure is called as lung compliance.
In compliance curve, at identical intrapleural pressure,
the volume of lung is less in inspiratory phase than in the
expiratory phase. This different pressure volume
relationship curve during inspiration and expiration is
known as 'hysteresis 'curve as represented by Figure
1.5.1.
Fig. 1.5.1: Compliance curve of lungs
98 VIVA IN MEDICAL PHYSIOLOGY
31. What is specific compliance? What is its advantage
to use?
The compliance when expressed as a function of FRC is
known as specific compliance.
In individuals with one lung only, lung compliance is
approximately half of the normal even if the normal
distensibility of normal lung is present. Similarly in children
compliance is lower than normal though the distensibility
of lung remains normal. This fallacy is removed with
specific compliance since FRC is proportionately reduced
and specific compliance remains essentially constant.
32. Why bronchial asthma is regarded as a disease of
expiratory obstruction?
During inspiration the thorax expands resulting fall of
intrathoracic pressure and thereby the pressure around
smaller bronchioles falls. This facilitates to expand the
bronchiole and thus air can flow inward but during
expiration intrathoracic pressure increases resulting
compression of smaller bronchioles and thus difficulty of
outward air flow takes place.
33. What is peak expiratory flow rate? What is its
significance?
It is the maximum flow rate during a single, forceful
expiration. It is valuable when measured serially to
establish the pattern of airway obstructive disease and
to monitor its responses in treatments especially in
asthma.
34. What do you mean by alveolar ventilation?
It is the amount of air comes in and out of the lung alveoli/
min. It is computed as follows:
Alveolar ventilation = (TV – dead space air) × RR/min
= (500 – 150) × 14/min
= 5 Lit/min.
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35. What do you mean by dead space air? Compare
between anatomical and physiological dead space
air?
The amount of air in the respiratory system which does
not take part in the gaseous exchange process is known
as dead space air.
Anatomical dead space is the amount of air present in
the conducting zone of the respiratory system where
exchange of gases does not take place. Its total amount
is approx. 150 ml. The physiological dead space or total
dead space includes the anatomical dead space and the
amount of the air in the alveoli specially apical portion of
lungs which does not take part in gaseous exchange
(alveolar dead space) process because of poor blood
supply.
36. What is ventilation-perfusion ratio?
It is the ratio of alveolar ventilation to pulmonary blood
flow. Normal value is 0.8.
37. What do you mean by diffusion capacity of lungs?
It is the amount of a gas that crosses the alveolar capillary
membrane per minute per mm Hg difference in partial
pressure of gas on the two sides of the membrane. Its
normal value is 20-30 ml/min/ mm Hg at rest.
38. Enumerate the factors affecting diffusion capacity.
These are:
i. Total surface area of the alveolar capillary
membrane—This is directly related with diffusion
capacity.
ii. Thickness of the membrane—Inversely related.
iii. Diffusion constant—Inversely related and depends
on.
a. Solubility of gases—directly related with diffusion
constant.
b. Molecular weight of the gases—inversely related.
100 VIVA IN MEDICAL PHYSIOLOGY
39. In case of damage of alveolar capillary membrane
diffusion capacity decreases and thus diffusion of
both O2 and CO2 should decrease. But practically
the persons suffer from lack of O2 only without any
sign and symptom of CO2 excess, why?
It is because the diffusion capacity of CO2 is 20 times
more than diffusion capacity of O2 and thus inspite of
damage of respiratory membrane a significant amount
of CO2 produced by the body diffuse to alveoli and thus
no symptoms of CO2 excess is found in the body.
40. What is O2 dissociation curve? What is its normal
shape?
The plot of percentage of O2 saturation of hemoglobin
against the partial pressure of O2 gives a sigmoid-shaped
curve which is known as O2 dissociation curve as
represented by Figure 1.5.2.
41. Why this curve is sigmoid?
A Hb molecule contains 4 atoms of Fe++each of which
combines with O2 in varried affinity. The combination of
1st heme in the hemoglobin molecule with O2 increases
the affinity of the 2nd heme for O2 and oxygenation of 2nd
heme increases the affinity of the 3rd and so on. This
shifting of affinity of Hb for O2 produces sigmoid shape.
Fig. 1.5.2: Oxygen-hemoglobin dissociation curve
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42. What is the significance of the sigmoid shape of O2
dissociation curve?
1. O2 dissociation curve has the plateau above 60 mm
Hg. This flat upper part indicates that even if the PO2
increases from 60 mm Hg to 300 mm Hg. The O2
content of the blood will not vary significantly. Similarly
the effect of O2 lack on the body will not be manifested
until the PO2 goes down below 60 mm Hg.
2. The steep slope of the curve indicates that the slight
decrease of PO2 will cause greater release of O2 from
hemoglobin.
43. What do you mean by shift to the right? Name some
situations when this takes place.
When the affinity of hemoglobin with O2 decreases, it
favours the release of O2 to the tissues or unloading of
O2 by the tissues. This is known as shift to the right.
Causes:
• Fall of blood pH due to either increased CO2 or
presence of any acid, i.e. acidemia.
• Increase in body temperature.
• Increase in 2-3 DPG concentration in blood.
44. What do you mean by shift to left? What may be its
causes?
When the affinity of hemoglobin to combine with O2
increases, there is less release of O2 in the tissues
whereas oxygenation in the lungs increases. This is
known as shift to left.
Causes:
• Rise in blood pH or alkalemia.
• Decrease in body temperature.
• Increase in carbon monoxide in blood.
• Presence of foetal hemoglobin.
• Increase myoglobin concentration and decrease 2-3
DPG concentration in blood.
102 VIVA IN MEDICAL PHYSIOLOGY
45. What is Bohr's effect?
Loading of CO2 to blood causes unloading of O2. This
phenomenon seen at tissue level is known as Bohr's
effect.
46. What do you mean by P50? What is its significance?
It means the PO2 at which the hemoglobin is half saturated
with O2. Its normal value is 26 mm Hg at PCO2 40 mm Hg,
pH 7.4 and temperature 37°C.
It serves as a convenient index of hemoglobin affinity
for O2. Higher is the P50, lower is the affinity of hemoglobin
for O2.
47. What are the vehicles of O2 transport and which
one is ideal and why?
Vehicles are - plasma and water of RBC and in
combination with of which Hb is ideal vehicle as other two
are not sufficient to meet the tissue demand of O2.
48. What is the O2 content in arterial and venous blood?
Arterial blood-19 ml%; venous blood - 14 ml%.
49. What is the partial pressure of O2 in arterial and
venous blood?
Arterial blood - 100 mm Hg; Venous blood- 40 mm Hg.
50. In which form O2 is carried from lungs to tissues
and in what amount?
• In dissolved form in plasma and RBC- 0.3 ml %
• In oxyhemoglobin form
- 18.7 ml %
51. What do you mean by O2 carrying capacity of blood?
It is the O2 carrying capacity of the total hemoglobin of
blood. If the Hb content of a person is 16 gm% then his
O2 carrying capacity will be 16 × 1.34 ml (each gram Hb
carry 1.34 ml O2), i.e. 21 ml per decilitre of blood.
52. What is the difference between O2 content and O2
capacity?
The O2 content refers to the amount of O2 actually present
in a given sample of blood where as O2 capacity refers
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to the total amount of O2 that can be carried by blood
when the hemoglobin is fully saturated with O2.
53. What is coefficient of utilisation?
The percent of blood that gives up its O2 as it passes
through the tissue capillaries is called as the coefficient
of utilisation. At rest it is about 25 per cent and during
heavy exercise it increases upto 75 per cent.
54. In which form CO2 transported in blood?
Mainly in 3 forms:
1. In dissolved form in plasma and RBC- 0.3 ml%
2. As bicarbonate form of Na+ and K+ - 3 ml%
3. As carbamino compound form
- 0.7 ml%
55. What is the CO2 content and partial pressure of CO2
in arterial and venous blood?
CO2 content
PCO2
Arterial blood-48 ml%
40 mm Hg
Venous blood-52 ml%
46 mm Hg.
56. In which form the venous CO2 is mostly found?
In bicarbonate form.
57. What are the effects of CO2 addition to blood?
It causes increase in plasma bicarbonate ion, decrease
in plasma chlorides and increase in RBC chlorides.
58. What do you mean by maximum venous point and
arterial point?
In deoxygenated blood with maximum PCO2, 60-67 mm
Hg, CO2 content is 65 ml% called as the maximum venous
point as represented by Figure 1.5.3. In oxygenated blood
at PCO2 40 mm Hg, CO2 content is 48 ml% called as the
arterial point as represented by Figure 1.5.3.
59. What do you mean by physiological CO2 dissociation
curve?
If we join maximum 'venous point' and 'arterial point' which
corresponds to extreme CO 2 level in the body
respectively, it will roughly reflect changes between PCO2
104 VIVA IN MEDICAL PHYSIOLOGY
and CO2 content in the blood and called the physiological
CO2 dissociation as represented by curve C of Figure
1.5.3.
Fig. 1. 5.3: CO2 dissociation curve in whole blood
60. What are the factors affecting CO2 dissociation
curve?
These are:
• Increase in body temperature shifts the curve to the
left, i.e. at increased body temperature larger amount
of CO2 can be taken by the blood at a given PCO2.
• Decrease in PO2 shifts the curve to the left and there
by helps in loading of CO2 in blood.
61. What is a Haldane effect?
Loading of O2 to blood favours the unloading of CO2.
This phenomenon seen at the lung level is known as
Haldane effect.
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62. What is chloride shift?
At the tissue level when CO2 enters into RBC of venous
blood there is formation of bicarbonate ion which quickly
diffuses out of RBC. This causes entry of one molecule
of Cl– from plasma to RBC to maintain the electrical
neutrality within RBC. This phenomenon is known as
chloride shift.
63. Why Cl– content of RBC in venous blood is more
than in arterial blood?
Because of chloride shift, i.e. entry of Cl– from plasma to
RBC at tissue level.
64. Why the size of RBC in venous blood is
comparatively more than in arterial blood?
Because of entry of CO2 in RBC at tissue level there is
addition of osmotically active substances, i.e. HCO3 ion
or Cl– in the RBC. This results absorption of water by the
RBCs and thus RBC becomes swollen. This also results
increase hematocrit value of venous blood (3% more than
arterial blood).
65. Name the respiratory centers?
It is of two types:
• Medullary respiratory center: located in the
ventrolateral medulla overlying the olivary nucleus. It
constitutes of 2 centres (neurons):
• Inspiratory neurons—causes inspiration
• Expiratory neurons—causes expiration.
• Pontine respiration center : it constitutes of 2 centers
as follows:
• Apneustic centre: Located in lower pons and
activates inspiratory neuron or centers of medulla
and thereby favours inspiration.
• Pneumotaxic centre: Located in upper pons and
contains both inspiratory and expiratory neurons
and thereby active in both phases of respiration. It
also inhibits the neurons of lower pons, i.e.
apneustic center and thus prevents apneusis.
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66. What do you mean by 'inspiratory ramp'?
The DRG neurons normally discharge the repetitive
bursts of action potentials which is weak in the beginning
and increases steadily for about 2 seconds followed by
abrupt cessation of the impulse generation for next 3
secs. This type of signal is known as Ramp signal or
Inspiratory ramp. Because of this signal inspiration starts
slowly and then reaches peak gradually followed by abrupt
turning off of inspiration resulting quiet expiration.
67. What is apneusis? How it can be resulted?
It is the arrest of respiration in inspiratory phase. It can
be experimentally resulted by transection in mid pons
along with sectioning of vagus nerves.
68. State the neural path for voluntary control of
respiration.
Pathway for such voluntary control of respiration like
voluntary hyperventilation, breath holding, etc. is
mediated through corticospinal pathway by passing the
medullary respiratory centers.
69. What is Hering-Breuer reflex?
During inspiration the lungs alveoli distend causing
stimulation of stretch receptors present at the walls of
alveoli. This results in transmission of afferent impulses
through vagus nerve to inhibit the inspiratory center and
thereby stops inspiration. This reflex is known as HeringBreuer reflex which is active in case of forceful breathing
of human beings.
70. What are J receptors? Which factors act as their
stimulant?
Hyperventilation of lungs stimulate unmyelinated vagal
afferent nerve endings located in alveolar wall,
juxtaposition to alveolar capillaries are called
juxtapulmonary capillary receptor or J receptors.
Stimulants are–hyperinflation of lungs, pulmonary
congestion, pulmonary edema, inhalation of strong
irritants.
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71. What is 'J' reflex?
When 'J' receptors are stimulated they inhibit spinal stretch
reflex and thus limit the power of contraction of skeletal
muscles including respiratory muscles. This reflex is
known as J reflex.
72. What do you mean by adrenaline apnoea?
Injection of adrenaline in high doses increases systemic
blood pressure which in turn inhibits the respiration called
adrenaline apnoea.
73. Name the chemoreceptors responsible for
regulation of respiration.
These are of 3 types:
• Peripheral chemoreceptors, e.g. aortic bodies and
carotid bodies.
• Central chemoreceptors-present in ventral surface of
medulla.
• Pulmonary and myocardial chemoreceptors.
74. What are the chemical stimulants which regulate
the respiration?
These are:
• Decrease of PO2
• Increase of PCO2
• Increase of H+ concentration or decrease of pH.
75. Out of these above mentioned stimulants which one
is potent?
It is the increase of PCO2.
76. Which stimulant is the only direct stimulant for
central chemoreceptor?
It is H+ concentration.
77. If both the inspiratory and expiratory centers are
equally and simultaneously stimulated action of
which will be dominant?
Inspiratory center.
108 VIVA IN MEDICAL PHYSIOLOGY
78. What is pulmonary chemoreflex?
Injection of veratridine or nicotine like alkaloid substances
into pulmonary capillaries stimulate chemoreceptors
present in pulmonary vessels producing bradycardia,
hypotension and apnoea followed by tachycardia. This
response is called pulmonary chemoreflex.
79. What do you mean by CO2 narcosis?
The accumulation of CO2 in the body depresses the CNS,
including respiratory centers and also produces
headache, confusion, dizziness, apnoea and eventually
coma. This ill effect of excess CO2 in the body is referred
as CO2 narcosis.
80. Define dyspnoea. What is dyspnoeic point?
It is defined as the breathing in which the person becomes
conscious of shortness of his breath and thereby
breathing becomes unpleasant and discomfort.
The level of pulmonary ventilation, when increased to a
certain level, results initiation of uncomfortable breathing
or dyspnoea is knwon as, dyspnoeic point. It is generally
4-5 times increase of normal pulmonary ventilation.
81. What is apnoea? What are its causes?
Apnoea is the temporary inhibition or stoppage of
breathing. The causes are–deglutition, after
hyperventilation, Bezold-Jarish reflex, Hering-Breuer
reflex and also during sleep.
82. What is sleep apnoea? What do you mean by sudden
infant death syndrome (SIDS)?
In few individuals, sometimes respiration becomes
inhibited or depressed with periods of apnoea during
sleep. This condition is known as sleep apnoea.
A form of sleep apnoea, more commonly seen in
premature infants where apnoea occurs during sleep, is
called as SIDS.
83. Why cardiac failure patients are preferred to sit
down than lying position?
It is because in lying position pulmonary congestion is
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increased and thereby decreases vital capacity which in
turn may aggravate the dyspnoeic condition
(orthopnoea).
84. What do you mean by breaking point? What is due
to?
If breathing is stopped voluntarily, a time will come when
the breathing can no longer be stopped forcibly. This
point where breathing starts automatically is known as
breaking point. It is due to increased arteriolar PCO2,
decreased arterial PO2.
85. Define asphyxia.
Inproper airation of blood due to O2 lack and CO2 excess
in blood is known as asphyxia.
86. What is the difference between fresh water and
sea water drowning?
In fresh water drowning as the hypotonic water enters in
the lungs alveoli there is continuous diffusion of water from
lung alveoli to capillary blood resulting hemodilution. This
inturn results swelling of RBC and ultimately hemolysis.
In case of sea water drowning the hypertonic fluid
enters in the lungs alveoli that initiate continuous diffusion
of water from capillary blood to alveoli resulting
hemoconcentration. This inturn results shrinkage of RBC
and no hemolysis but decrease in blood volume.
87. Define periodic breathing. Classify it.
Periodic breathing is the repeated sequence of apnoea
followed by respiration. It is of 2 types: Cheyne stokes
breathing and Biot's breathing.
88. What is Cheyne-Stokes breathing? Name the
conditions when this type of breathing occur?
The repeated sequence of gradual onset of apnoea
followed by gradual restoration of respiration is called as
Cheyne-Stokes breathing as represented by Figure 1.5.4.
110 VIVA IN MEDICAL PHYSIOLOGY
Fig. 1.5.4: Cheyne-Stokes breathing pattern
It is seen during following conditions:
Physiological: Voluntary hyperventilation, high altitude, and
sometimes during sleep.
Pathological: Left heart failure, uremia and brain damage.
89. Define Biot's breathing. In which condition it is
seen?
The periodic breathing in which there are 3-4 cycles of
normal respiration followed by abrupt onset of apnoea
and again abrupt onset of respiration is known as Biot's
breathing.It is seen in some pathological conditions like
meningitis and medullary disease.
90. What do you mean by eupnoea and hyperapnoea?
Eupnoea means the normal rate and amplitude of
respiration whereas hyperapnoea means the increased
rate and amplitude in breathing.
91. What is hypercapnoea and hypocapnoea?
Hypercapnoea is the excess of CO2 in the body fluid
whereas hypocapnoea is the decreased of CO2 in the
body fluid.
92. What is tachypnoea and bradypnoea?
Tachypnoea is rapid breathing where as bradypnoea is
the decreased rate of breathing.
93. Enumerate the types of apnoea.
Types of apnoea are:
• Voluntary apnoea,
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Vagal apnoea,
Anoea vera (due to change in blood pressure),
Acapnic apnoea (due to complete lack of CO2),
Deglutition apnoea,
Sleep apnoea,
Adrenaline apnoea.
94. What are the causes of asphyxia?
These are–CO2 excess, O2 lack and change in blood
pH.
95. What are the various stages of asphyxia?
These are hyperapnoea, respiratory convulsions and
stage of exhaustion.
96. What are the various factors causing respiratory
insufficiency?
These are–alveolar hyperventilation, decrease in
pulmonary diffusion capacity and decrease in O2 transport.
97. What is hypoxia? Enumerate its type.
Hypoxia is the condition characterised by the lack of O2
in the tissue. It is of 4 types—hypoxic, anaemic, stagnant
and histotoxic hypoxia.
98. Define hypoxic hypoxia. What are its causes?
The condition characterised by a low arterial PO2 keeping
O2 carrying capacity of blood and rate of blood flow
normal or elevated is known as hypoxic hypoxia.
Causes:
• Low PO2 in inspiratory air
• Reduced pulmonary ventilation
• Decrease in gaseous exchange through alveolar
capillary membrane.
99. Define anemic hypoxia. What are its causes?
Hypoxia in which arterial PO2 is normal but the amount of Hb
available to carry O2 is reduced, is known as anemic hypoxia.
Causes: Anaemia, hemorrhage, formation of carboxy
hemoglobin or methaemoglobin.
112 VIVA IN MEDICAL PHYSIOLOGY
100. Define stagnant hypoxia. What are its causes?
The hypoxic condition in which the blood flow to the tissues
is reduced inspite of normal arterial PO 2 and Hb
concentration is known as stagnant hypoxia.
Causes: Circulatory failure, heart failure, hemorrhage,
etc.
101. Define histotoxic hypoxia.
Hypoxia in which the amount of O2 delivered to the tissues
is adequate but the tissues cannot utilise the supplied
O2 because of the action of toxic agent within it, is called
histotoxic hypoxia.
102. What do you mean by O2 poisoning.
Inhalation of O2 in high O2 pressure that occurs when O2
is breathed at a very high alveolar oxygen pressure like
in Caisson may result seizures followed by coma in most
people. The other symptoms include nausea, muscle
twitching, dizziness, disturbances of vision, irritability, etc.
This phenomenon is called as O2 poisoning.
103. In case of severe pulmonary failure, O2 therapy may
cause death, why?
In case of severe pulmonary failure, there is both hypoxia
and hypercapnoea present. In this situation whatever
respiration is there that is due to hypoxic stimulation of
peripheral chemoreceptors. O2 therapy in this stage can
cause inhibition of respiration resulting further depression
of respiration centers by severe hypoxia and
hypercapnoea. This may cause death.
104. Define cyanosis. What are its common sites?
Cyanosis is the bluish colouration of skin and/or mucosa
membrane due to presence of at least 5 gm of reduced
hemoglobin per 100 ml of blood in the capillaries. Its
common sites are:
• Mucous membrane of undersurface of tongue.
• Lips
• Ear lobes
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RESPIRATORY SYSTEM 113
Nailbeds
Tip of the nose.
105. In which type of hypoxia cyanosis cannot take place
and why?
• In anemic and histotoxic anemia, cyanosis is absent.
• In case of anemic hypoxia, the amount of Hb becomes
too low and thus enough reduced Hb to produce blue
colour is lacking.
• In case of histotoxic hypoxia, O2 is not taken up by
the tissues and thereby there is minimum chance to
produce reduced Hb in greater amount to produce
cyanosis.
106. Compare the central and peripheral cyanosis?
Central cyanosis
Peripheral cyanosis
1. It is due to hypoxic hypoxia.
It is due to stagnant hypoxia.
2. Extremities become warmer
due to increase blood flow to
the tissue and hypertension
which reflexly produce vasodilatation.
Extremities become cooler due to
decrease tissue blood flow and
hypotension.
107. What do you mean by Caissons disease?
It is the condition caused by sudden release of pressure
if Caisson under water is suddenly brought out. This
results the abdominal pain, disturbance of vital center in
CNS and even sudden collapse of a person present within
the Caisson.
108. What do you mean by N2 narcosis?
If the body is exposed to high atmospheric pressure,
because of high N2 pressure larger amount of N2 will enter
into lungs and thereby in body fluids ultimately causing
euphoria, impairement of mental function and symptoms
of alcoholic intoxication. These effects of N2 in higher
pressure is called N2 narcosis.
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109. How does effect of N2 narcosis can be avoided?
By adopting two methods:
• By using O2 helium mixture instead of N2 - O2 mixture
in Caisson.
• By gradual release of pressure from the Caisson.
110. What is high pressure nervous syndrome (HPNS)?
At high atmospheric pressure O2 helium mixture used in
Caisson can produce tremor, drowsiness, depression of
activity in EEG. This condition is known as HPNS.
111. Name different lung function tests.
These are:
• Measurement of FRC
• Measurement of dead space
• Measurement of VC and FEV1
• Measurement of lung volume and capacities
• Measurement of PO 2 and PCO 2 in inspiratory,
expiratory and alveolar air.
112. What is acute mountain sickness?
In some instances, the compensatory mechanism to high
altitude breaks down and gives rise to serious symptoms
known as Monge's disease or acute mountain sickness
characterised by:
• Considerable increase of red cell mass and PCV.
• High pulmonary arterial pressure.
• Right heart failure in some cases.
113. What is chronic mountain sickness?
It is the disease occurring in case of failure of long-term
acclimatization process to the residents of high altitude.
The signs and symptoms are:
• Extreme polycythemia
• Increase in viscosity of blood that results fall of blood
flow
• Increase in BP
• Cyanosis, fatigue, exercise intolerance
• Pulmonary oedema.
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114. What are the acclimatization to the natives of high
landers?
The acclimatization that occurs in the residents who are
residing in the high altitude permanently for generations
after generations, are as follows:
• Short body stature and large sized chest that results
high ratio of ventilatory capacity to body mass.
• Hypertrophy of right heart.
• Polycythemia
• Shifting of O2 dissociation curve to right
• Increase in size of carotid bodies.
115. What are the aims of artificial respiration?
These are:
• Avoiding asphyxia to brain
• Oxygenation of body tissue
• Ventilation of lung
• Stimulation of spontaneous breathing.
116. What are the indications of artificial respiration?
Artificial respiration is given to the subject in case of
following conditions:
a) Acute respiratory failure due to:
• Overdose of anesthetic agent
• CO poisoning
• Drowning
• Electric shock
• Hanging
• Intake of narcotic drugs
• Resuscitation of new born
b) Chronic respiratory failure due to:
• Diphtheria
• Poliomyelitis
• Ascending paralysis
117. What do you mean by CPR?
If the respiration fails along with stoppage of heart beat
this procedure is followed till the person is not hospitalised
for proper treatment. The procedures are:
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•
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Cleaning of the airways
Mouth to mouth breathing at the rate of 16-18/min
External cardiac massage by pressing lower border
of sternum by 4-5 cm at the rate of 80-90 times/min.
After every 15 cardiac massage two mouth to mouth
(15:2) breathing (if two subjects are present.
After every 5 cardiac massage 1 mouth to mouth (5:1)
breathing (if one subject is available).
118. What do you mean by Kussmaul breathing?
During some clinical conditions like diabetic coma there
is rapid and deep breathing eliminating CO 2 and
bicarbonate. This type of rapid and shallow breathing is
known as Kussmaul breathing.
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1.6
Nerve Muscle Physiology
1. Why nerve cells do not divide?
It is because of absence of centriole.
2. What is the structural and functional unit of
nerves? Enumerate its components.
The structural and functional unit of nerve is neuron. It
consists of cell body or soma, axon, dendron and
dendrites.
3. Classify the neuron.
The neurons can be classified by 3 different approaches
as follows:
A. Depending on the function: On the basis of it's
function neuron is classified as:
a) Motor neurons: These carry the motor impulses
from CNS to the peripheral effector organs. This
is why it is also known as efferent nerves. The
motor neurons have long axons and short
dendrites.
b) Sensory neurons: These carry the sensory
impulses from peripheral organs or tissues to the
CNS and is also known as afferent nerves. These
neurons have a short axon and long dendrites.
B. Depending on the polarity : As per this it is divided
into 3 types - Unipolar, Bipolar and Multipolar neurons.
a) Unipolar: In this type of neuron both the processes
of neuron i.e. axon and dendrite originate from
one pole or site of cell body. This type of nerve
cell is present only in embryonic stage in human.
118 VIVA IN MEDICAL PHYSIOLOGY
b) Bipolar: In this type of neuron axon and dendron
arise from two different pole.
c) Multipolar: This has many poles, i.e. one of the
poles gives rise to the axon and all the other give
rise dendrites.
C. Depending on the length of axon: On the basis of
the length of axon neurons are of two types - Golgi
type-I and Golgi type -II.
a) Golgi type I neurons: In this type of neurons the
axons are long and the cell body is present in
CNS and their axons reach the remote peripheral
organs.
b) Golgi type- II neurons: These neurons have short
axons and are present in cerebral cortex, spinal
cord, etc.
4. What is 'nodes of Ranvier'? What are the functions
of myelin sheath?
The axon of neuron is surrounded by a protein-lipid
complex called myelin sheath except at its endings and
also at periodic constrictions about 1 mm apart. This part
of axons where there are no myelin sheath present, is
called 'nodes of Ranvier'.
Functions of myelin sheath:
• Prevents cross-stimulation of adjacent axons due to
its high insulating property.
• Facilitates rapid conduction of nerve impulse.
• Protects and provides the nutrition to the axoplasm.
5. Compare the myelinated and unmyelinated nerves.
Myelinated
Unmyelinated
1. Presence of myelin sheath.
Absence of myelin sheath.
2. Location - in all preganglionic
fibers of ANS and somatic
nerve fibers more than 1µm
diameter.
Location - in all post-ganglionic
fibers and somatic nerve fibers
of <1µm in diameter.
3. Conduction rate through it is fast.
It is rather slow.
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6. Name different types of glial cell.
These are the supporting cells in nervous system and
mainly are of 3 types.
• Microglia—These are phagocytic cells that enter the
CNS from meninges and blood vessels.
• Astrocytes—These are found throughout the brain
joining to the blood vessels and investing synaptic
structures, neuronal bodies, neuronal processes. It
helps in support, transport, inflammatory reaction and
also helps in forming blood-brain barriers.
• Oligodendroglia—These are the cells that form myelin
around axon within CNS.
7. What is nerve growth factor? Mention their
function.
Nerve growth factors are protein in nature present in
salivary glands, plasma and in many different tissues,
necessary for the growth and maintenance of sympathetic
neurons.
Function: Helps in growth and maintenance of
sympathetic neurons and also some sensory neurons
and cholinergic neurons in brain.
8. Enumerate the heat production in nerve fiber.
Heat is evolved by the nerves during its activation in 3
phases as follows:
• Resting heat—It is the amount of heat produced while
nerve is inactive.
• Initial heat:
— Immediately after muscular activity is started, heat
is produced by the working muscle which is
dependent on anaerobic changes in the muscle.
This heat is named as initial heat.
— It occurs during action potential.
— It is anaerobic and coincides with the spike
potential.
— It is due to breakdown of ATP and creatine
phosphate (CP)
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•
Delayed or recovery heat:
— Delayed heat is the heat liberated during
relaxation process of a muscle
— It is aerobic and 30 times of the initial heat.
— Here, energy is used for resynthesis of ATP and
CP.
9. What do you mean by accommodation in relation to
neuron? Which nerves have less power of
accommodation-sensory or motor?
If a nerve is submitted to the passage of a constant
strength of current, the site of the nerve under stimulation
shows decrease of excitability after sometime. This
property of fiber is known as accommodation. Sensory
nerve has less power of accommodation.
10. What do you mean by saltatory conduction?
In case of myelinated nerves, the wave of depolarisation
jumps from one node of Ranvier to the next as myelin
sheath is impermeable to ions. This is responsible for
rapid transmission of nerve impulse. This type of jumping
of depolarisation from node to node is called as saltatory
conduction.
11. What do you mean by orthodromic and antidromic
conduction?
When an action potential is initiated in the middle of an
axon or neuron, it can be conducted in either direction
but the impulses normally pass in one direction, i.e. from
receptor or synaptic junction of a neuron to the synaptic
knob of that particular neuron down the axon. Such
conduction is called as orthodromic conduction.
Conduction in opposite direction is called as antidromic
conduction seen in sensory nerve supplying the blood
vessels.
12. Which one is the best form of artificial stimulus for
the nerve fiber and why?
It is the electrical stimulus as:
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NERVE MUSCLE PHYSIOLOGY 121
Its intensity and frequency can be precisely controlled.
It can be applied to a specific site.
It does not cause any injury.
13. What is the thermal range for nerve fibers activity?
It varies, though the normal range is 0°C to 50°C.
14. What do you mean by normal coefficient of nerve
impulse?
It means that within physiological range the velocity of
nerve impulse is doubled with every 10°C rise of
temperature.
15. What do you mean by nerve impulse?
Nerve impulse is the state of electronegativity by
depolarisation at point of stimulation of nerve fiber and
its propagation throughout its length.
16. What do you men by All or None law? Is it applicable
in nerve bundle or muscle mass?
If a nerve fiber is stimulated by a stimulus it will be excited
(depolarised) maximally or not at all. This relationship
between the stimulus and response is known as All or
None Law. It is applicable only in a single nerve fiber or
single muscle fiber not in a nerve bundle or muscle mass.
17. What is the relation of thickness of nerve fiber with
the velocity of nerve impulse?
It is directly related, i.e. the more the thickness of the
nerve, the more is its velocity of conduction rate.
18. Why does temporary paralysis is seen after sitting
cross leged for long periods?
It is due to the loss of conduction in motor, touch and
pressure fibers due to prolonged pressure on a nerve.
In this case pain sensation remains unaltered.
19. What is the Bell and Megendie's classification of
nerve fiber?
It is based on the direction of impulse. On this basis it is
of two types:
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•
Afferent fibers that carry impulse from periphery to
center.
Efferent fibers that carry impulse from centre to
periphery.
20. What are the Erlanger and Gasser classification of
nerve fibers?
As per this classification it is divided into mainly 3 groups:
• A fibers which are further subdivided into α, β , γ and
δ.
• B fibers
• C fibers.
21. What do you mean by 1st degree and 5th degree
injury of nerve fiber?
• First degree injury is the temporary impairment of
nerve function due to ischaemia caused by direct
pressure to a nerve for a limited time.
• Fifth degree injury means the complete transection
of nerve fiber.
22. What is chromatolysis?
After the sectioning of nerve fibers the Nissl's granules
of cell body of a nerve disintegrates and loose their
staining reaction, thereby cell becomes colourless. This
event is known as chromatolysis.
23. Define neuromuscular junction.
The junction between the motor nerve and skeletal muscle
fiber is called neuromuscular junction.
24. What are palisades? What are their importance?
In the neuromuscular junction, underneath the nerve
endings, the muscle membrane of motor end plate is
thrown into folds called palisades. It increases the surface
area on which neurotransmitters can act.
25. What is end plate potential (EPP)?
In response to binding with neurotransmitter, e.g. ACh
on post-synaptic membrane, the post-synaptic membrane
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NERVE MUSCLE PHYSIOLOGY 123
undergoes depolarisation due to Na+ influx. This wave of
depolarisation below the threshold level is called as end
plate potential which is not propagatory in nature.
26. What is MEPP? Differentiate EPP and AP.
During rest there is very small potential changes (upto
0.5 mv) can be recorded from the motor end plate even
if there is no impulse. This is known as MEPP.
EPP
AP
1. Non-propagatory in nature
2. It does not obey all or none law
Propagatory in nature
Obeys all or none law
3. It can be summated
Cannot be summated.
27. What is giant end plate potential (GEPP)?
In experimental animals, inhibition of MEPP results in
production of GEPP due to release of more quantity of
ACh. This results more depolarisation of motor end plate
though not sufficient to produce action potential.
28. What is myasthenia gravis? What are its common
sites?
Myasthenia gravis is characterised by rapid onset of
fatigue with marked generalised weakness of muscles
due to damage of nicotinic ACh receptors by circulating
antibodies on the post-synaptic membrane of
neuromuscular junction.
Common site is extraocular muscle, facial muscle,
swallowing and mastication muscle.
29. What is Lambert-Eaton syndrome?
It is also characterised by the weakness of muscle caused
by the antibodies against Ca++ channels in the nerve
ending at the neruomuscular junction. This decreases
Ca++ influx to the synaptic knob and thereby decreases
ACh release to the synaptic cleft.
30. Classify and compare different types of muscle.
Muscle is of 3 types—skeletal, cardiac and smooth.
124 VIVA IN MEDICAL PHYSIOLOGY
Parameters
Skeletal
Cardiac
Smooth
1. Location
Attached to the
bone
In heart
In hollow viscera
like GIT,
blood vessels.
2. Structure
Presence of
Presence of well-Lack cross
well-developed developed cross-striations.
cross-striations striations
3. Control
Non-syncytial
Functionally
syncytial
Can be both.
Single unitfunctional
syncytial,
Multiunit- non
syncytial
Voluntary
Involuntary
Involuntary
31. What is due to the cross-striation in the skeletal
muscles?
It is due to the difference in the refractive index of various
parts of muscle fiber. Dark band is due to the highly
refractile material (myosin) and light band is due to the
lower refractile material (actine, tropomyosin and
troponin).
32. What is the contractile unit of muscle? Define it.
Sarcomere is the contractile unit. The area of the muscle
fiber in between two adjacent Z lines is called as
sarcomere.
33. Enumerate thick and thin filaments?
Thick filaments are myosin each of which is comprised of
a short compact head known as heavy meromyosin
(HMM) and a long tail called light meromyosin (LMM).Thin
filaments are comprised of:
• Actin: Which are of two types-G actin (globular) and
F actin (fibrous)
• Tropomyosin
• Troponin: Which are of again 3 types-troponin I,
troponin T and troponin C.
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34. What is the contractile machinery of muscle? What
is the main function of myosin?
Actin and myosin are the contractile machinery. Main
function of myosin-it has ATPase activity and thereby
converts ATP to ADP with formation of initial energy
needed for muscle contraction.
35. What do you mean by sarcotubular system? What
is triad?
It is the specialised system within the muscle fiber
responsible for conduction of electrical impulse from
sarcolemma to the interior of muscle fiber. It is made-up
of two structures.
• Transverse tubular system—extension of sarcolemma
into muscle fibers at A-I junction.
• Longitudinal sarcoplasmic reticulum—sac like
structure of dialated sarcoplasmic reticulum (SR)
known as terminal cisternae.
There is a close proximity of the terminal cisternae
and the T system. Transverse tubules with two adjacent
terminal cisternae in opposite site is called as triad.
36. What do you mean by E-C coupling?
The process by which depolarisation of the muscle fiber
initiates contraction of muscle is called as E-C coupling.
37. What changes take place in sarcomere during
active muscle contraction?
During contraction A band remains unchanged in length
whereas H and I bands are shortened.
38. What is contractile component of muscle?
Contractile component represents the elasticity of thick
and thin filaments and is of two types:
• Series elastic component (SEC)—example: tendon
• Parallel elastic component (PEC)—example:
connective tissue and sheath.
126 VIVA IN MEDICAL PHYSIOLOGY
39. What do you mean by optimum and equilibrium
length of muscle?
Optimum length is the length of the muscle in which it
develops maximum active tension. Equilibrium length is
the length of the relaxed muscle cut free from its bony
attachments.
40. What do you mean by isotonic and isometric
contraction?
During muscular contraction when the length of the
muscle remains same and no external work is done then
that type of contraction is known as isometric contraction
whereas the muscle contraction in which length of the
muscle changes while tension remains constant is called
as isotonic contraction.
41. How does muscle length remain same during
isometric contraction?
By two ways:
• All the muscle fibers in a group of muscle do not
contract at the same time. Some contract, others are
kept in relaxed thereby shortening of some fibers are
compensated by relaxation of others.
• Any shortening in muscle length gets compensated
by stretching of the SEC, i.e. tendon therefore, length
remains same.
42. Why does no external work is done in isometric
contraction?
As distance through which weight is moved is almost zero
and as work done is equal to force timed distance,
therefore the external work done is also zero.
43. What do you mean by freeload and after load? In
which condition work done is greater?
• After loaded contraction is the contraction of muscle
in which the load acts on the muscle only after it starts
to contract. In a free loaded contraction, the load acts
on the muscle before it starts to contract.
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NERVE MUSCLE PHYSIOLOGY 127
Freeloaded muscles do more work than an afterloaded
muscle upto a physiological limit. It is due to the
increase of initial length of muscle fiber due to
stretching of muscle by the load in rest.
44. Define motor unit. What do you mean by recruitment
of motor unit?
Each single motor neuron and all the muscle fibers
supplied by each single motor neuron is called as motor
unit.
Recruitment of motor unit: When an excitatory nerve is
stimulated with a stimulus of constant strength for a long
time, there is a progressive increase in the reflex
response. This is due to the progressive increase in the
number of motor neurons activated. This phenomenon
is known as recruitment of motor unit. It is similar to the
effect of temporal summation.
45. What is size principle?
Fast or white muscles are innervated by fast conducting,
i.e. myelinated motor neurons. Whereas slow or red
muscles are innervated by slow conducting, i.e.
unmyelinated motor neurons. This is known as size
principle.
46. Contrast between fast and slow muscles?
White (fast) muscles
Red (slow) muscles
Muscle fibers are large in
diameter.
Moderate in diameter.
Contain high amount of
glycogen and ATPase (That is
why pale or white).
Moderate glycogen level with low
ATPase activity.
Innervated by large and
myelinated nerves.
Innervated by small and slow, i.e.
unmyelinated fibers.
These are specialised for fine
Respond slowly and adapted for
skill movements, e.g. extraocular. long, slow and posture maintaining
muscles and muscles in hand.
contractions.
Easily fatigued.
Resistant to fatigue.
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47. Define a simple muscle twitch. What are duration
of a muscle twitch in fast and slow muscle fibers?
A single and brief electrical shock of adequate intensity
applied to the motor nerve gives a single action potential
which in turn causes a brief contraction followed by
relaxation of muscle. This response is called as 'A simple
muscle twitch'.
• Duration of a twitch in fastest muscle is 7.5 msec.
• Duration of a twitch in slowest muscle is 100 msec.
48. What do you mean by make and break stimulus?
In neuromuscular preparation, galvanic current causes
stimulation both at make and break point. At make,
stimulus starts from cathode and is called as cathodal or
make stimulus whereas at break, stimulus starts from
anode and is called as anodal or break stimulus.
49. State Bois Regmond's law?
It states that it is only at make or break a nerve can be
stimulated.
50. What do you mean by ascending and descending
current?
In nerve muscle preparation, if anode lies close to muscle
and direction of current is away from it, it is called as
ascending current whereas if cathode is nearer to the
muscle and direction of current is towards muscle it is
known as descending current.
51. What is electrotonus?
It is the altered physiological state around the electrode
point in a nerve fiber due to constant current.
52. What is meant by the terms 'tension' and 'load'?
Tension is the force exerted by a contracting muscle on
an object and load is the force exerted by the weight of
an object on a contracting muscle. Thus in true sense
tension and load are opposing forces.
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53. Define minimal and maximal stimulus.
Minimal stimulus is the amount of weakest current that
can produce a muscle contraction whereas the maximal
stimulus is the current which produces the strongest
contraction of a muscle which is capable of by a single
stimulus.
54. What is rheobase and chronaxie?
Rheobase is the weakest intensity of constant current in
volts capable of exciting the muscle. It is about 0.2-0.3
volts. Chronaxie is the minimum duration required to
contract (exite) the muscle by the intensity of current
strength of twice of rheobase.
55. What is latent period?
It is the time taken to contract the muscle in response to
its stimulation and is denoted from point of stimulation to
beginning of contraction.
56. What is true latent period?
If the muscle is directly stimulated and if an optical
recording system is employed to exclude the inertia of
the mechanical lever then the latent period is much
reduced. The latent period still present in that condition
is known as true latent period.
57. Define refractory period. In which muscle it is
maximum?
It is a short period of ineffectivity or unresponsiveness of
second stimulus applied at a very short interval after the
1st stimulus. Cardiac muscle has the largest refractory
period.
58. Define fatigue. Which one is the seat of fatigue?
Fatigue is defined as progressive and temporary loss of
excitability in a muscle due to its continuous stimulation.
In nerve muscle preparation, seat of fatigue is in
neuromuscular junction where as in whole body it is in
nerve cell or even in CNS.
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59. If two successive stimulus is applied to motor
nerve in a nerve muscle preparation the effect of
2nd stimulus becomes greater. What is this
property known as? What is due to?
It is known as beneficial effect which is due to the following
reasons:
• Increase in temperature.
• Accumulation of metabolites.
• Decrease in viscosity of muscle.
60. What do you mean by treppe response or staircase
phenomenon? What is its cause?
When a series of maximal stimuli are applied to nerve
muscle preparation in such a way so that successive
stimuli falls during the relaxation phases of the previous
stimulus, the tension developed during each twitch
increases gradually and successively till a uniform tension
per contraction is reached. This successive increase of
tension of each twitch is called as treppe response or
staircase phenomenon.
It is due to increase availability of Ca2+ for binding
troponin C.
61. What do you mean by Tetanus? What is complete
and incomplete tetanus?
When a series of repetitive stimuli are applied in muscle
at a rate high enough to cause summation of contraction
so that there is continuous contraction with no ralaxation
at all, that state is termed as tetanus. In such a tetanic
contraction when there is no relaxation between stimuli it
is called as complete tetanus as represented by Figure
1.6.1 (in left panel) whereas when there are periods of
incomplete relaxation between the summated stimuli it is
known as incomplete tetanus as represented by Figure
1.6.1 (in right panel)
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Fig. 1.6.1: Genesis of tetanus
62. What is rigor mortis?
After death the muscle fibers develop a state of extreme
rigidity due to complete depletion of ATP and
phosphocreatine. This state of rigidity of the muscle after
death is called rigor mortis.
63. How do you record temperature changes in the
muscles?
By using an instrument named thermopile.
64. Define steady state?
When body can maintain a steady rate of O2 usage to
keep the lactic acid produced by muscular activity
constant by balancing its rate of formation and removal,
this state is called as steady state.
65. What is O2 debt?
After a period of severe muscular exercise the amount of O2
consumed is enormously more than the amount of O2
consumed under resting condition. This extra amount of
oxygen which is utilised for reversal of some metabolic process
is known as O2 debt. The metabolic processes are:
• Resynthesis of glucose from lactic acid accumulated,
• Resynthesis of ATP and creatine phosphate.
132 VIVA IN MEDICAL PHYSIOLOGY
•
Restoration of amount of O 2 dissociated from
hemoglobin and myoglobin.
66. What do you mean by muscular fasciculation?
It is a spontaneous contraction of motor units which is
visible through the skin as fine ripping movement in the
relaxed muscles.
67. What is second wind?
During exercise after an initial dysponea there is again
adjustment in respiration and circulation and the subject
is said to have got second wind.
68. What is electromyography?
It is the procedure to obtain the record of muscular activity
by using electromyograph and helpful to diagnose
neuromuscular disorder like myasthenia gravis,
myotonias, etc.
69. What are the morphological features of cardiac
muscle?
These are as follows:
• Presence of intercalated disc which is extensive folding
of cell membrane at the point of contact of two muscle
fibers. It provides strong union between fibers.
• Presence of gap junction which provides rapidity of
conduction of impulse.
• Presence of functional syncytium.
• Highly vascular, well-developed sarcotubular reticulum
with plenty cytoplasm, mitochondria and rich in
glycogen.
70. What is the difference between sarcotubular
system of heart and skeletal muscle?
In both the muscles, it is well developed but in the cardiac
muscle 'T' system penetrates the sarcomere at Z Line
and therefore there is only one triad per sarcomere but
in skeletal muscle there are 2 triads per sarcomere as T
system penetrates at A-I junction and as 2 A-I junctions
are present in each sarcomere.
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71. Why does atrial and ventricular muscle fibers do
not have pre-potentials?
It is because of K+ permeability is constant in those
muscles during diastole.
72. What is calcium rigor?
Increase Ca ++ concentration in ECF, increases
myocardial contractility with marked increase in serum
Ca++, that relaxes heart less in diastole and finally stops
in systole. This condition of heart is known as calcium
rigor.
73. Differentiate between pre-load and after-load.
Pre-load
1. This is the load which acts on
the muscle before it begins to
contract.
After-load
This is the load which acts on the
muscle after it begins to contract.
2. It results isometric contraction. It causes isotonic contraction.
3. In vivo it is the degree to which It is the resistance against which the
the myocardium is stretched
ventricles pump the blood.
before it contracts.
74. Why does cardiac muscle do not have fatigue? Why
it can't be tetanised?
It does not have fatigue as the refractory period is too
long and during this period replenishment of energy takes
place and thereby no exhaustion of energy.
It can't be tetanised as absolute refractory period is too
long and hence summation of contractile response is not
possible.
75. What do you mean by plasticity of muscle?
The length tension relationship of muscle is called as
plasticity of muscle.
76. What is excitatory junctional potential (EJP)?
In smooth muscles in which adrenergic discharge is
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excitatory, stimulation of the adrenergic nerve produces
discrete partial depolarisation that resembles small end
plate potential. These potential changes are called as
EJP.
77. What is the source of energy in a smooth muscle?
These are mainly fatty acids, acetoacetic acid and
glucose in lesser extent.
78. What are the types of a smooth muscle fibers?
Where are they located?
It is of two types: Single unit and multi-unit.
• Single unit: (Named as they function as functional
syncytial fashion)–Present in GIT, uretors, bronchi,
uterus, urinary bladder.
• Multi-unit: (Non-syncytial)-Iris, cilliary muscles of eye,
pilomotor muscle of skin and muscles of blood vessels.
79. What is muscle tone?
The living skeletal muscles are always in the state of
partial sustained contraction. This is known as muscle
tone.
EXCRETORY SYSTEM 135
SECTION I : THEORY VIVA
1.7
Excretory System
1. What is the anatomical and physiological unit of
kidney?
It is nephron.
2. Which kidney is not palpable normally? When it
becomes palpable?
Left kidney is not usually palpable. It becomes palpable
when it is enlarged or low in position.
3. Classify and differentiate between types of
nephron.
It is of two types: cortical and juxtamedullary:
Parameters
1. Amount
Cortical nephron
Juxtamedullary nephron
85%
15%
2. Size of glomerulus
Small
Large
3. Site of glomerulus
In outer cortex
Junction of cortex and
medulla (Inner cortex)
4. Size of Henle's loop
Small
Long
5. Vascular supply
Through
peritubular
capillaries
Through vasa recti and
peritubular capillaries
6. Rate of filtration
7. Function
Slow
Fast.
Reabsorption and concentration of urine
secretion
4. Enumerate the components of nephron.
It consists of:
136 VIVA IN MEDICAL PHYSIOLOGY
1. Renal corpuscle—Which is made up of two structuresBowman's capsule and glomerulus
2. Renal tubule—It is a long tube containing different
segments named as proximal convoluted tubule
(PCT), Henle's loop, distal convoluted tubule (DCT),
collecting tubule (CT) and collecting duct.
5. Mention the non-excretory functions of kidney.
1. Homeostatic function: It maintains the constancy of the
internal environment, i.e. ECF by regulating body fluid
volume, body fluid composition via conserving and
excreting water and solutes and pH of the body fluid.
2. Endocrine function: It secretes different hormones or
hormone like substances in different condition e.g.:
Renin secretion, Erythropoietin secretion, Mudullipin
secretion (which is secreted from renal papilla and
acts in opposite to renin - angiotensin mechanism to
regulate arterial BP) and conversion of Cholecalciferol
(Vit D3) to 1-25 Dihydroxy cholecalciferol which helps
in regulation of Ca2+ concentration in body fluids.
3. Metabolic function: In unusual condition like prolonged
starvation, chronic respiratory acidosis kidney
synthesises and releases glucose from noncarbohydrate source by gluconeogenesis.
6. What is the rate of blood flow through the kidney?
It is 1200-1300 ml/ min.
7. What peculiarities of renal circulation help the
kidney to work even in chronic renal disease?
It is because of presence of Ludwig shunt.
8. What is the rate of glomerular filtrate formation?
It is 125 ml/min and 180 L/day.
9. What is filtration fraction? What does it represent?
It is the ratio of glomerular filtration rate and plasma flow
rate, i.e.
FF = GFR/PFR = 130/700 = 0.18
It is a measure of filtering efficiency of glomerulus.
SECTION I : THEORY VIVA
EXCRETORY SYSTEM 137
10. Name the factors affecting GFR along with its
relationship.
These are as follows:
• Glomerular capillary hydrostatic pressure—directly
related with GFR.
• Glomerular capillary oncotic pressure—inversely
related with GFR.
• Bowman's capsular hydrostatic pressure—directly
related.
• Bowman's capsular oncotic pressure—inversely
related.
• Permeability of glomeruler capillary—directly.
• Surface area—irectly related with GFR.
11. What are the factors affecting renal blood flow?
• Exercise: Exercise decreases the RBF by increasing
the sympathetic activity which results vasoconstriction
in renal bed, i.e.
Exercise →increase in sympathetic activity →increase
in release of NE/Angiotensin- II→ vasoconstriction in
afferent arteriole → decrease in RBF.
• Posture: In sudden change of posture from supine to
standing the RBF falls due to:
Change of posture from supine to standing →
decrease in BP → reflex increase of sympathetic
activity → vasoconstriction → decrease in RBF.
• High protein diet: It increases RBF by increasing the
glomerular capillary pressure.
• BP: Increase in renal arterial BP →reflex reduction in
sympathetic tone → renal arteriolar dilatation →
increase in RBF
• Neurohumoral substances:
– Norepinephrine, Angiotensin- II → decrease in
RBF
– Prostaglandins, ACh →increase in RBF
138 VIVA IN MEDICAL PHYSIOLOGY
12. Enumerate the factors affecting GFR.
The factors affecting the GFR are:
• Bowman's capsular hydrostatic pressure (PB)
• Glomerular capillary hydrostatic pressure (PG): It is
further determined by (i) Arterial pressure (ii) Renal
blood flow (iii) Afferent arteriolar resistance and
(iv) Efferent arteriolar resistance.
• Glomerular capillary oncotic pressure (πG)
• Bowman's capsular oncotic pressure (πB)
• Filtration coefficient (Kf): It is further determined by
permeability of the glomerular capillary membrane and
surface area and thus both these factors determine
GFR by influencing Kf.
13. Which method of renal function tests is most
preferred clinically? What are its advantages?
Creatinine clearence test. It is a simple method as no
intravenous infusion is required.
14. What do you mean by filtered load and excretory
load?
The amount of a substance that appears in urine/unit time
is called as excretory load whereas the amount of solute
transported across the glomerular membranes per unit
time is called as filtered load or tubular load. It is calculated
as filtered load = blood glucose level × GFR/100.
15. What do you mean by high threshold, low threshold
and no threshold substances?
Some of the contents of glomerular filtrate like glucose,
Na + , K + , water, Ca ++ , etc. are reabsorbed almost
completely. These are known as 'high threshold
substances' whereas some contents like urea, uric acid,
phosphates are reabsorbed to some extent only and are
known as 'low threshold' and the substances like creatinine
and sulphates are not reabsorbed at all which are called
as no 'threshold substances'.
SECTION I : THEORY VIVA
EXCRETORY SYSTEM 139
16. What is transport maximum (Tm) limited
mechanism?
According to this, substances like glucose, certain amino
acids are completely reabsorbed under certain
concentration beyond which those are excreted in the
urine.
17. What is gradient time limited mechanism?
If the substances are allowed to stay more in the renal
tubles, there is more reabsorption of that substances by
the renal tubules. This kind of mechanism of reabsorption
of substances like Na+ is known as gradient time limited
mechanism.
18. What is obligatory reabsorption?
When the reabsorption of substances are not controlled
or concerned with regulating levels of substances in the
body, it is known as obligatory reabsorption. Eighty per
cent of NaCl and water reabsorption is obligatory in
nature.
19. What is facultative reabsorption?
When reabsorption of substances take places according
to the need of the body and is regulated by some
regulatory substances in the body, it is called as
facultative reabsorption. 20% of NaCl and water
reabsorption through DCT and CT is through ADH and
therefore, it is an example of facultative reabsorption.
20. What is Tm limited mechanism? Give the Tm value
of glucose, amino acid, creatinine, PAH and plasma
protein.
For substances that are actively reabsorbed or secreted
by the renal tubules, there is a maximum rate at which
they are reabsorbed or secreted. This maximum rate of
transport is known as transport maxima or Tm.
140 VIVA IN MEDICAL PHYSIOLOGY
Tm value for some substances
Substances
Tm value
Tm of actively reabsorbed substances:
Glucose
320 mg/min
Amino acids
1.5 mg/min
Plasma proteins
30 mg/min
PO4=
0.1 mg/min
SO4=
0.06 mg/min
Tm of actively secreted substances:
Creatinine
16 mg/min
PAH
80 mg/min
21. Name the substances reabsorbed by renal tubules
along with the site of reabsorption.
Substances
Site of reabsorption
%age of reabsorption
Na+ (98%)
PCT
DCT
CT
80 %
15 %
2-3 %
K+
PCT
DCT & CT
90 %
10 %
Cl–
PCT
Henle's loop
70-85 %
15-30 %
HCO3–
PCT
DCT& CT
85-90 %
10-15 %
Glucose
Water
PCT
PCT
DCT & CT
100 %
70-85 %
15-30 %
22. What do you mean by tubular maxima for glucose
(TmG)?
Critical level at which filtered load of glucose exceeds
the capacity of reabsorption system through renal tubules
is called as tubular maximum for glucose.
23. What is renal threshold for glucose?
It is the plasma level of glucose at which glucose first
SECTION I : THEORY VIVA
EXCRETORY SYSTEM 141
appears in the urine in more than the normal minute
amount. Its value is 180 mg%.
24. If TmG is 320 mg/min still why does glucose appears
in the urine when the plasma glucose level is 180
mg% at which the tubular load is 225 mg/min?
This is because all tubules within the kidney are not
capable of absorption of same (equal) amount of glucose.
Some tubules have much lower TmG than others. In these
tubules some glucose remain unabsorbed even at a lower
plasma glucose level and thus is excreted in urine. This
phenomenon is known as 'Splay'.
25. What is the chief function of juxtamedullary and
cortical nephrons?
Juxtamedullary nephrons are mainly responsible for water
reabsorption through counter current system and cortical
nephrons are mainly responsible for Na+ reabsorption.
26. Enumerate JGA along with its function.
The JGA is a combination of specialised tubular and
vascular cells located at the vascular pole where the
afferent and efferent arterioles enter and leave the
glomerulus. It is composed of 3 types of cells:
• Juxtaglomerular or JG cells—Present in afferent
arteriolar wall mainly and also in efferent arteriolar
wall, where these enter and leave glomerulus. These
cells are responsible for synthesis, storage and
release of enzyme renin and also hormone
erythropoietin.
• Mucula densa cells—These are present in distal tubule
part and they function as chemoreceptor and are
stimulated by decrease NaCl concentration in tubular
fluid passing through DCT.
• Mesangial cells or lacis cells—These are supporting
cells found between capillary loops. They also play a
role in the regulation of glomerular filtration because
of its contractile property.
142 VIVA IN MEDICAL PHYSIOLOGY
27. What do you mean by tubuloglomerular feedback?
In response to change of NaCl concentration in distal
tubular fluid (Decrease NaCl concentration) there is
stimulation of macula densa cells which in turn stimulates
JG cells to release renin. This renin by series of events
ultimately controls GFR. This mechanism is known as
tubulo-glomerular feedback mechanism.
28. What is filtration coefficient?
It is the function of the capillary surface area and the
membrane permeability (i.e. surface area × membrane
permeability). This determines the GFR in some
pathological condition.
29. Define uniport, co-transport and antiport with
suitable example.
• Uniport: This is the mechanism by which the carrier
protein present in the cell membrane causes
transportation of a single molecule in one direction
only.
– Example: facilitated diffusion of glucose.
• Co-transport or symport: The mechanism by which
the carrier proteins present in the cell membrane
transports two particles together in same direction is
called as symport or co-transport.
– Example: secondary active transport of glucose.
• Antiport or counter transport: The mechanism by which
the carrier proteins of the cell membrane transports
two or more molecules in opposite direction is known
as antiport or counter transport.
– Example: Na +- K+ pump operated in the cell
membrane.
30. What is normal blood urea level?
It is 15-40 mg%.
31. What is normal urea clearance level?
If urine excretion is 2 ml or more per minutes then the
amount of urea excreted in urine is known as maximum
SECTION I : THEORY VIVA
EXCRETORY SYSTEM 143
clearance which is 72 ml/min, whereas if urine excretion
is less than 2 ml/min then the amount of urea excreted in
urine is known as standard clearance which is 24 ml/min.
32. What is normal insulin and creatinine clearance?
It is 120-130 and 80-110 ml/min respectively.
33. What are the salient features of a substances used
for measuring GFR? Name some of them.
It has to be following features:
• It should be freely filtered.
• It should be neither reabsorbed nor secreted and nor
metabolised.
• It should not be toxic.
• It should not alter the hemodynamics.
Such substances are- inulin, creatinine, mannitol, sorbitol,
radio-iodine, etc.
34. What is the average daily urea formation in the
body?
In human it is 25-30 gm/day.
35. What are the main symptoms of uraemia?
These are drowsiness, headache, muscular twitching and
weakness, vomiting, metabolic acidosis, hypertension,
anaemia and cardiac arrhythmias.
36. Which is the major source of ammonia formation
by the kidney?
It is glutamate.
37. What do you use to determine GFR and RBF?
Inulin for GFR and PAH for RBF.
38. At what stage does chronic renal failure occur?
When normal function of kidney falls to 25 per cent or
below than its normal function or loss of 75 per cent or
more nephrons take place then chronic renal failure
occurs.
39. How does dilute or concentrated urine is formed?
It is by counter current system.
144 VIVA IN MEDICAL PHYSIOLOGY
40. What are the components of countercurrent system
and the parts of the kidney associated with it?
The components are:
• Counter current multiplier system—Henlee's loop,
medullary interstitium and collecting duct of kidney
are associated with this system.
• Counter current exchanger system—Vasa recta and
medullary interstitium are associated with this system.
41. What do you mean by metabolic acidosis and
alkalosis?
Metabolic acidosis is defined as the fall of blood pH below
the normal range due to excess CO2 produced in the
body whereas metabolic alkalosis is referred to as the
rise of blood pH above the normal value due to deficient
formation of CO2 by the body.
42. What is the physiological and anatomical capacity
of urinary bladder?
• Anatomical—700 to 800 ml.
• Physiological—250 to 450 ml.
43. What do you mean by cystometrogram? On the
basis of which law it is plotted?
Cystometrogram is the plot of intravesicular pressure
against the volume of fluid in the urinary bladder as
represented by Figure 1.7.1. It manifests Laplace's law.
Fig. 1.7.1: Cystometrogram
SECTION I : THEORY VIVA
EXCRETORY SYSTEM 145
44. What is micturition waves? What is due to?
In cystometrogram, superimposed on the tonic pressure
changes during filling of urinary bladder, there are
periodic acute rise in the pressure called micturition waves
which lasts from few seconds to more than a minute.
It is due to stretch reflex initiated by stretch receptors
present in the urinary bladder and proximal urethra.
45. What is micturition reflex?
When the pressure within urinary bladder is increased
above 100 cm of H2O, a nervous reflex is initiated to void
the urine or desire to urinate. This reflex is called as
micturition reflex.
46. What is residual urine and retention of urine?
In all types of urinary bladder dysfunction, bladder
contracts but contractions are insufficient to empty the
bladder completely, therefore some amount of urine is
left in the urinary bladder called residual urine.
During spinal shock, activity in detrusor muscle remains
suspended for long period but activity in sphincter tone
returns early. In this case then bladder responds purely
and passively to distension with urine like an elastic bag
resulting retention of urine.
47. What do you mean by retention with overflow?
During spinal shock as a result of retention of urine,
bladder becomes increasingly overstretched and
sphincters are finally forced to open resulting escape of
small amount of urine at frequent intervals. This is known
as retention with overflow or passive incontinence or
overflow incontinence.
48. What do you mean by 'Automatic bladder', 'Isolated
bladder' and 'Spastic neurogenic bladder'?
• In case of tabes dorsalis patients there may be failure
of micturition at regular intervals causing accumulation
of urine in urinary bladder resulting either precipitation
of involuntary automatic evacuation of bladder or
146 VIVA IN MEDICAL PHYSIOLOGY
•
•
dribbling of urine. In this situation bladder is known as
automatic bladder.
In case of denervation of both afferent and efferent
nerves, the urinary bladder becomes flaccid and
distended called as isolated or decentralised bladder.
Repeated infection of urinary bladder causes
hypertrophy of urinary bladder and micturition reflex
becomes hyperactive resulting contraction of bladder
at irregular intervals even along with small amounts
of urine called as spastic (contracted) neurogenic
bladder.
SECTION I : THEORY VIVA
SKIN AND BODY TEMPERATURE REGULATION 147
1.8
Skin and Body
Temperature Regulation
1. Name the functions of skin.
Skin has varried functions. The important functions are:
Protection,Regulation of body temperature,Excretion,
Synthetic function, Receptive function, Secretory function,
Absorptive function, Water balance and Storage function
(the dermis of the skin and subcutaneous tissue can store
fats, water, salts and glucose).
2. Classify the sweat gland and differentiate it.
Sweat glands are of two types: Eccrine and apocrine.
Parameter
Eccrine
Apocrine
i. Location
Found in all over
the body
Found in axilla, mons
pubis, scrotum, nipple, etc.
ii. Type of secretion
Clear, watery
and thin
Milky, opalescent and
having characteristic
smell on decomposition.
iii. Stimulus
Increase of body
temperature
Stress and sexual
stimulation.
3. What do you mean by homiothermic and poikiothermic? Give examples of each.
• The animals capable of maintaining constant body
temperature inspite of wide variations in environmental
temperature are known as homiothermic (warm
blooded) animals, e.g. man, mammals, birds.
148 VIVA IN MEDICAL PHYSIOLOGY
•
Whereas the animals showing variation of body
temperature in accordance with environmental
temperature are called as poikiothermic or cold
blooded animals e.g. reptiles, fish, amphibians, etc.
4. What is the normal body temperature in man? What
do you mean by comfortable or neutral zone
temperature?
Normal BT of man is 98.4°F or 37°C.
Comfort zone: It is the ambient temperature at which there
is no active heat gain or heat loss mechanism operated
by the body. It is 27 ± 2°C.
5. What is the normal skin and oral temperature?
• Normal oral temperature: 36.3 -37.1°C (97°F - 98.8°F)
• Normal skin temperature: 29.5°C-33.9°C (85°F-93°F)
6. What is basal temperature? Give the value of core
temperature. What are the site for recording core
temperature?
Basal temperature is the body temperature recorded
under complete physical and mental rest which is
recorded generally in morning after awaking.
Core temperature is 0.5°C to 1°C more than oral
temperature, i.e. its value is 37.5°C to 38°C in an
average.
Site of recording of core temperature includes rectum,
vagina, esophagus and tympanic membrane.
7. What will be the effect on body if core temperature
is changed in following ways?
• If it is decreased to 26°C or less—It will lead to death
of that person due to cardiac failure.
• If it is increased to 43.5°C or more—It will lead to death
due to heat stroke.
• If it is increased to 41°C for prolonged period—There
will be irreversible brain damage.
SECTION I : THEORY VIVA
SKIN AND BODY TEMPERATURE REGULATION 149
8. Why regulation of body temperature is required?
It has following reasons:
• Speed of chemical reaction in the tissues varies with
temperature.
• Enzyme system of our body has got narrow range of
optimum temperature at which it functions properly.
Thus the normal body function depends on a relatively
constant body temperature.
9. What is the average daily sweat secretion?
It is about 1 lit/day.
10. What are the main functions of sweat?
It helps to regulate body temperature, maintains water
electrolyte and acid-base balance, helps to excrete some
excretory products and also keeps the skin moist.
11. What do you mean by thermal sweating, nonthermal sweating, emotional sweating?
• Thermal sweating: It occurs in response to rise of
environmental or body temperature and mediated by
eccrine sweat glands.
• Non-thermal sweating: When sweating is stimulated
by increased epinephrine level in the blood this type
of sweating is called as non-thermal sweating. It is
mainly mediated through apocrine type of gland.
• Emotional sweating: This is the type of sweating which
takes place during emotion controlled by premotor
area of cerebral cortex.
12. How thermal sweating is controlled?
It is by hypothalamus.
13. Name the main tissues where heat is produced in
most.
It is in liver and muscle.
14. Name the heat gain mechanisms.
These are: shivering, increase in TSH and adrenaline
secretion, continuous indirect vasoconstriction.
150 VIVA IN MEDICAL PHYSIOLOGY
15. What are the heat loss mechanisms?
These are: by radiation from the body to cooler object,
by conduction and convection to surroundings, by
evaporation through sweating, by excreta in urine and
faeces.
16. Name the main calorigenic hormones in the body.
It is adrenaline and thyroxin.
17. How much is the approximate daily heat loss through
various channels?
Through skin-2200 cal.; through lungs-150 cal; through
warming of air and food-100 cal; through urine and
faeces-50 cal.; total = 2500 cal.
18. What is the role of brown fat in BT regulation?
Brown fat which plays a role in BT regulation mainly in
infants, is present between the scapula, at the nape of
neck, along the great vessels in the thorax and abdomen.
These fat cells contain mumerous mitochondria and
thereby by increasing fatty acid oxidation it produces
heat.
19. What do you mean by insensible perspiration?What
is its role in BT regulation?
Insensible perspiration is the passage of water by
continuous diffusion through the epidermis which cannot
be seen or felt. Its amount is 50 ml/hr.
It helps in loosing the heat from the body by 30 Kcal/
hour.
20. Why one feels hotter in a humid day?
In a humid weather, the heat loss by evaporation becomes
difficult as rate of evaporation depends on relative
humidity. As humidity is high, the rate of evaporation
becomes low and thereby heat loss becomes less.
21. Name the heat gain and heat loss centre.
Heat loss centre is posterior hypothalamus whereas heat
gain center is anterior hypothalamus.
SECTION I : THEORY VIVA
SKIN AND BODY TEMPERATURE REGULATION 151
22. Can a person be made poikiothermic?
Yes, Lesion in posterior hypothalamus causes body
termperature to fall towards environmental temperature
as both hot and cold regulating mechanisms are
destroyed as anterior hypothalamic fiber passes via the
posterior hypothalamus.
23. What is critical temperature?
It is defined as the temperature at which a naked body
needs the help of accessory chemical reactions to
maintain the BT.
24. What is pyrexia and hyperpyrexia?
Pyrexia is the state of the body when BT ranges from
37.2°C to 40.5°C (99°F to 105°F) where as hyperpyrexia
is the state when BT rises above 40.5°C or 105°F.
25. What is hypothermia and deep hypothermia?
Hypothermia is a state of body when BT falls to 30°C32°C whereas deep hypothermia is a state when BT falls
below 25°C.
26. What do you mean by heat stroke, heat cramp and
heat exhaustion?
• Heat stroke: It is caused due to high environmental
temperature, i.e. more than 41°C resulting impairment
of body temperature regulating mechanism.
• Heat exhaustion: It is caused by excessive sweating
in response to heat which results loss of water, sodium
chloride through sweat and thereby reduction of blood
volume.
• Heat cramps: Sometimes in people working in hot
weather the muscles become hyperexcitable due to
excessive loss of Na+ and Cl¯ from the body due to
excessive sweating. This condition is called as heat
cramps.
152 VIVA VOCE IN PHYSIOLOGY
1.9
Central Nervous System
1. What are neuroglia and its function?
Neuroglia are the supporting cells in the nervous system
of which star-shaped cells are called as astrocytes and
cells with few processes are called as oligodendroglia
and very small sized cells are termed as microglia.
The main function of neuroglia is to provide support
and protection of nervous tissues. In addition, they supply
some nutrition to the nerve cells, neutralise the toxins
and function as the RE system.
2. Classify motor neurons.
It is of two types:
i. α neurons: Innervate large skeletal muscle.
ii. γ neurons: Innervate special skeletal small muscle
fibers called intrafusal fibers.
3. What is synapse?
A synapse is the junction between two neurons for the
passage of the nerve impulse.
4. What do you mean by presynaptic, subsynaptic and
postsynaptic membranes?
Presynaptic: It is the membrane of neuron in close
approximation with the membrane of postsynaptic cell in
a synapse.
Subsynaptic: Surface of the cell membrane involved in
the synapse is called as the subsynaptic membrane.
CENTRAL NERVOUS SYSTEM 153
SECTION I : THEORY VIVA
Postsynaptic: The remainder of the motor neuron cell
membrane is called as the postsynaptic membrane.
5. Distinguish between electrical and chemical
synapses.
Chemical
Electrical
1. Impulse is transmitted from pre Impulse is transmitted through gap
to post-synaptic site through
junction.
release of neurotransmitter i.e.
chemical mediators.
2. Most of synapses are chemical Present only in specific synaptic
type
junction of brain.
3. Presence of synaptic cleft
Cleft is replaced by low resistance
bridges
4. Synaptic delay is present
Absent
5. Sensitive to O2 lack
Insensitive to O2 lack.
6. What is EPSP and IPSP?
In response to binding of neurotransmitter on the receptor
present in postsynaptic membrane there is opening of
ligand gated Na+ channels. This results inward diffusion
of Na+ causing alternation of membrane potential towards
electro-positive.This non-propagative electrical potential
which ultimately initiates action potential is called as
excitatory postsynaptic potential or EPSP.
Whereas when inhibitory neurotransmitters bind on the
PSM there is opening of ligand gated K+ or Cl– channels
resulting hyperpolarisation of PSM. This is known as IPSP.
7. Differentiate between EPSP and AP.
EPSP
AP
1. Stimulus intensity to generate EPSP
has no threshold
Has threshold level
2. Does not obey all or none law
3. Absence of refractory period
Obeys all or none law
Present
4. Summation can occur
Never possible
5. Non-propagatory
Propagatory.
154 VIVA VOCE IN PHYSIOLOGY
8. What are the properties of generator potential?
The properties of GP are:
(i) It is non-propagatory in nature
(ii) It is monophasic
(iii) It does not obey all or none law.
9. What do you mean by spatial and temporal
summation?
• Simultaneous stimulation of two afferent nerves by a
stimulus of subthreshold intensity can evoke action
potential in motor neuron. This property is known as
spatial summation.
• Whereas if subminimal stimuli are repeated at short
intervals in a single nerve, reflex action can also be
evoked which is known as temporal summation.
10. What is the fractionation phenomenon?
Direct stimulation of motor nerve results more response
than reflex response or in other words the tension
developed reflexly is always a fraction of response that
is produced by direct motor nerve stimulation. This is
known as fractionation phenomenon.
11. What is after-discharge?
Continuation of discharge of impulses from motor neuron
even after withdrawal of stimulation from sensory side is
called as after-discharge.
12. What do you mean by law of forward conduction?
Synapse permits the conduction of impulse from
presynaptic to postsynaptic neuron only, i.e.
unidirectionally. This property is known as law of forward
conduction.1
13. What is occlusion and subliminal fringe?
When two afferent nerves to a skeletal muscle are
simultaneously stimulated, it is sometimes seen that, the
tension developed by the muscle under observation is
less than the sum of the tension developed by each
SECTION I : THEORY VIVA
CENTRAL NERVOUS SYSTEM 155
afferent nerve stimulated separately due to the
overlapping of afferent fibres in their central distribution.
This property is known as occlusion. The opposite
phenomenon is called as subliminal fringe.
14. What is synaptic plasticity?
Synaptic transmission can be increased or decreased
on the basis of past experience. This property is known
as synaptic plasticity.
15. Why receptors are called as biotransducers?
Receptor has got the capability to convert any form of
energy (stimulus, i.e. touch, pressure, pain, temperature,
etc.) to electrical energy (action potential). That is why it
is known as biotransducer.
16. What do you mean by proprioceptive impulse?
Which receptors are responsible for this?
The impulses which are concerned with the activity of
the body itself with regard to position and movements of
different parts of the body are known as proprioceptive
or kinaesthetic impulses.
Receptors are muscle spindle, joint receptors, Golgi
tendon organ and vestibular receptors.
17. Name the receptors responsible for following
sensations—touch, pressure, hot, cold and pain.
• Touch—Markel’s disc or Meissner’s corpuscle
• Pressure—Pacinian corpuscle
• Hot—Ruffini’s end organs
• Cold—Krause’s end bulb
• Pain—Free nerve endings.
18. Classify the receptors.
Receptors are generally classified into two types:
1. Exteroceptors—This gives response to stimuli arising
from outside the body. These are further subdivided
into 3 groups:
• Cutaneous—These are mechanoreceptors
present in the skin and are of 4 types as per the
nature of stimulus.
156 VIVA VOCE IN PHYSIOLOGY
• Touch receptors—like Meissner’s corpuscle
and Merkel’s disc.
• Pressure receptors—like Pacinian corpuscle.
• Thermo receptors—like Krause’s end bulb
for cold and Ruffini’s end organ or warm
temperature.
• Pain receptors—like free nerve endings.
• Chemoreceptors—These give response to
chemical stimuli. Examples: Taste buds for taste
sensation and olfactory cells for smell sensation.
• Telereceptors—These are stimulated in response
to the stimuli arising away from the body like Hair
cells of Organ of Corti for hearing and rods and
cones in retina for vision.
2. Interoceptors—These give response to stimuli arising
within the body. These are of two types:
• Viscero receptors—present in viscera and are
stimulated either-by stretch (stretch receptor) or
pressure (baroreceptor), or chemicals (chemoreceptor) or osmolarity of body fluid (osmo receptors).
• Proprioceptors: These are stimulated in response to
the change in position of different body parts. These
include receptor in labyrinth apparatus and muscle
spindle, golgi tendon, pacinian corpuscle, etc. in
muscle, ligament, joint, tendon, etc.
19. What do you mean by law of adequate stimulus?
Each type of receptor gives maximum response to a
particular or specific stimulus. However it can give
incomplete response to other type of stimulus provided
the intensity of stimulus is higher. For example, warm
water stimulates Ruffini’s receptor at lower intensity of
stimulus producing a specific response though it also
stimulates the free nerve endings of pain at high intensity
of stimulus and this response is incomplete. This property
of the receptor is known as Law of Adequate Stimulus or
Specificity of Response.
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20. What is Weber Fechner law?
The frequency of action potential in a sensory nerve is
directly proportional to the magnitude of generator
potential which inturn is directly proportional to the
intensity of stimulus. This relationship betwen intensity
of stimulus, magnitude of GP and frequency of AP in the
afferent nerve is known as Weber Fechner law.
21. What do you mean by tonic and phasic type of
receptors?
• Tonic receptors are poor, slow and incompletely
adapting receptors, i.e. they can be stimulated
continuously for many hours even if the intensity of
stimulus remains absolutely constant over many days,
e.g. muscle spindle, pain receptor, baro and
chemoreceptor for BP.
• Phasic receptors are rapidly adapting receptors and
transmit signals only when the stimulus strength is
changed and thus the generator potential in them is
short and decays rapidly, e.g. touch, olfactory,
pressure receptors.
22. What is Muller’s doctrine of specific nerve energy?
Sensation produced by impulses generated in a receptor
depends on the specific part of brain, i.e. the specific
pathways for specific sensation are separated from nerve
organ to cerebral cortex. This is known as Muller’s law.
23. What do you mean by law of projection? What is
phantom limb?
No matter where a particular sensory pathways is
stimulated along its course to the cortex, the conscious
sensation produced is referred to the location of the
receptor. This principle is called as law of projection.
A limb that has been lost by accident or amputation,
the patient usually experiences intolerable pain and
proprioceptive sensations in the absent limb and is called
as phantom limb.
158 VIVA VOCE IN PHYSIOLOGY
24. What do you mean by law of intensity
discrimination?
The brain interpretes different intensities of sensations
by variating the frequency of AP generated by receptor
and/or by variating the number of receptors activated or
both. This is known as law of intensity discrimination.
25. How it is possible to tell whether the pain is mild or
mederate or severe?
The information about the intensity of stimulus is
perceived by the sensory cortex through two mechanisms
as follows:
• By variating the frequency of the action potential
generated by the given receptor in response to a
stimulus.
• By altering the number of receptors involvement to
transmit the impulse i.e. the more the strength of
stimulus, the more the number of receptors activated
(Recruitment of sensory units). This property
explains how it is possible to tell whether the pain is
mild, moderate or severe; touch is crude or fine.
26. Name the reflexes which are of mainly clinical
importance.
Tendon reflex and pupillary light reflex.
27. Enumerate the characteristics of a reflex arch.
Excitibility, summation, delay, refractory period, fatigue,
facilitation, irradiation, fractionation, subliminal fringe,
occlusion, etc.
28. What is positive Babinski’s sign?
If plantar side of foot is scratched it normally causes
dorsiflexion of toes. In lesion of pyramidal tract, the
response is extension along with fanning of toes. This is
termed as postive Babinski’s sign which is also normally
seen in infants.
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29. Name the components of reflex arch.
Receptor, afferent nerve, centre, efferent nerve and
effector.
30. What is Bell–Magendie law?
In the spinal cord, the dorsal roots are sensory in nature
whereas the ventral roots are motor. This principle is
known as Bell-Magendie law.
31. Classify reflex with example depending on number
of synapse.
• Monosynaptic, e.g. bicep, tricep and knee jerk.
• Polysynaptic, e.g. withdrawal reflex, pupilary reflex.
32. Differentiate intrafusal and extrafusal fibers?
Each muscle spindle contains 2-12 muscle fibers enclosed
in a connective tissue capsule called as the intrafusal
fibers whereas the regular contractile units of muscle are
extrafusal muscle fibers.
33. What are nuclear bag and nuclear chain fibers?
Intrafusal muscle fibers are of two types. In one type many
nuclei are present in a centrally dilated area called as
nuclear bag fiber whereas in other type a single line of
nuclei are present lying in a chain and fibers are shorter
and thinner than 1st type which are known as nuclear
chain fibers.
34. What do you mean by static and dynamic response
in relation to stretch reflex?
The nerve endings in the nuclear bag fibers discharge
most rapidly when the muscle is being stretched and less
rapidly during sustained (continual) stretch. This is called
as dynamic response.
Whereas the afferent nerve endings in the nuclear
chain fibers discharge at an increased rate throughout
the period of sustained stretch only called as static
response.
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35. What do you mean α−γ linkage?
For the maintenance of muscle tone, the impulses from
the γ motor neuron causes contraction of end portion of
intrafusal fibers resulting stretching of muscle spindle.
This leads to the discharge of impulses from the primary
sensory nerve endings. These impulses stimulate the a
motor neurons of spinal cord which in turn send impulses
to extra-fusal fibers and cause contraction of extrafusal
muscle. This is known as α−γ linkage.
36. What is reciprocal inhibition?
When a stretch reflex is induced, activity of afferent fibers
from muscle spindle excites the motor neurons supplying
the muscle from which the impulses come and inhibits
those supplying its antagonist muscle. This phenomenon
is called as reciprocal inhibition.
37. What is inverse stretch reflex?
If muscle spindle is stretched by noxious stimulus (strong,
intense stretching) instead of contraction of the muscle
there will be relaxation of the concerned muscle. This
type of reflex is called as inverse stretch reflex.
38. Compare monosynaptic and polysynaptic reflex.
Parameter
Monosynaptic
Polysynaptic
1. No of synapse
Only one
Many
2. Latent period
Shorter
Comparatively longer
3. Important feature
Do not have
phenomenon
of after-discharge
Present
4. Example
Stretch reflex
Withdrawal and superficial reflex.
39. What are the effects of sectioning of posterior
nerve root?
There is loss of all forms of sensations, muscle tone,
superficial and deep reflexes and visual sensibility.
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40. What are the effects of section of anterior nerve
root?
These are—complete paralysis of muscle with loss of
voluntary and sensory movements, loss of reflexes and
vasomotor paralysis with muscle atrophy, sympathetic
system paralysis.
41. What is the cause of spinal shock?
Immediately after the spinal transection there is a state
of depression for some short period called as spinal
shock. It is due to release phenomenon which is set up
owing to cessation of impulses from higher levels, which
normally produce facilitating effect.
42. What are the symptoms of spinal shock?
• Many reflexes are lost causing flaccidity of limb muscle.
• Muscle tone is completely lost.
• BP is lowered.
• Retention of urine in bladder.
• Penis is flaccid and erection is impossible.
43. What do you mean by paraplegia and quadriplegia?
In case of complete spinal transection, if both the lower
limbs get paralysed the condition is called as paraplegia
and if all 4 limbs are paralysed it is called as quadriplegia.
44. What are the effects of complete spinal transection
in man?
The effects are divided in 3 stages:
• Stage of shock—Immediately there is loss of all
movements and sensation below the level of lesion.
BP becomes low and rectal and urinary bladder
sphincters are contracted.
• Stage of reflex activity—After 2-3 weeks some reflex
activity is regained that results the movement of
locomotion to some extent though walking without
support is impossible, BP becomes normal, sphincters
become less tonic allowing passing of urine and stool.
There is also preponderance of flexor muscles over
extensors so that there is semiflexion of lower limbs.
162 VIVA VOCE IN PHYSIOLOGY
•
Stage of failure of reflex activity—Reflexes disappear
again and muscles are wasted if the patients of spinal
transection suffer from general infection or toxaemia.
45. What do you mean by hemisection of spinal cord?
What is Brown-Sequard syndrome?
Lesion of one lateral half of spinal cord is known as
hemisection.
Brown-Sequard syndrome states that—below the level
of lesion in spinal cord on the same side there is extensive
loss of motor activity but little sensory loss, whereas on
the opposite side there is extensive sensory loss but little
motor loss.
46. What do you mean by decerebrate preparation?
Decerebrate preparation means sectioning at midbrain
level so that body function is controlled by spinal cord,
medulla, pons and cerebellum without having any
influences from midbrain and structure above the
midbrain.
47. What are the symptoms of decerebrated animals?
• High arterial pressure with intact cardiac and
respiratory reflexes.
• Respiration continues and swallowing and vomiting
can take place.
• Temperature regulation and righting reflexes are lost.
• Extensor reflexes are exaggerated resulting rigidity
of limbs called as decerebrate rigidity.
48. What is decorticate preparation?
Removal of entire cerebral cortex is known as decorticate
preparation.
49. What is syringomyelia?
This is a condition involving the gray matter around the
central canal of spinal cord in which excessive growth of
neuroglial tissue occurs with cavity formation. It first
affects the posterior horn of lower cervical and upper
CENTRAL NERVOUS SYSTEM 163
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thoracic regions. There is sensory loss with muscular
weakness and if progressed there is also loss of pain
sensation with trophic ulcers, injuries and vasomotor
disturbances.
50. What is dissociated anaesthesia?
In case of syringomyelia there is loss of pain and
temperature sensation whereas sense of touch is
unaffected. This conditon is known as dissociated
anaesthesia.
51. What is tabes dorsalis?
Degenaration of dorsal (sensory) roots specially in dorsal
column and fibers which carry pain sensation is known
as tabes dorsalis. Usually it is caused by syphilis.
52. Which sensations are carried by these nerves?
Fasciculus gracilis and
Fasciculus cuneatus
Fine touch, tactile localisation, kinesthetic
movements, vibration, deep pressure.
Lateral spinothalamic
Pain and temperature.
Ventral spinothalamic
Crude touch.
53. Differentiate superficial and deep pain.
Parameter
Superficial
Deep
Location
Skin and subcutaneous
tissue
Muscles and holow viscera
Nature
Sharp and well localised
Dull and poorly localised
Function
Leads to reflex
withdrawal movements,
increase in HR, BP and
respiration.
Produces faintness, nausea,
vomiting, sweating, fall in BP.
164 VIVA VOCE IN PHYSIOLOGY
54. Distinguish between Aδ
δ and C fibers.
Aδ fibers
C fibers
1. Small myelinated, 2-5 µm
diameter, 12-30 mm/sec.
conduction velocity.
Nonmyelinated, 0.4-1.2 µm diametar
with conduction volocity 0.5-2 mm/sec
2. Less in number
Relatively more
3. Conduct impulse only to
noxious stimulus.
In response to thermal and mechanical
stimulus.
4. Sensitive to electrical
stimulus.
Less sensitivity
5. Most sensitive to pressure
Most sensitive to local anaesthetics and
chemical factors.
55. What do you mean by fast and slow pain?
Fast pain is due to activation of Aδ nerve fibers and are
bright, sharp and well localised where as slow pain is
due to activation of C group of nerve fibers and causes a
dull, intense, diffuse and unpleasant feeling of pain.
56. What is Lewis-P factor?
Muscle activity releases group of substances like K+,
adenine nucleotides, lactic acid, PG, etc. which produces
pain and are collectively termed as Lewis-P factor.
57. What is referred pain?
The sensation of pain if experienced at the site of other
than the injured or diseased part is known as referred
pain, e.g.
• During heart attack pain is often experienced in the
inner aspect of left arm and left shoulder instead of
heart.
• Stone in gallbladder referred to the tip of the shoulder.
• Pain in testicles due to stone in the uretor.
58. Which sensations are carried by Dorsal Column
Medial Lemniscus system?
This system carries the sensation like fine touch, two point
discrimination, vibration sense, sense of position.
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59. Which sensations are carried by anterolateral
pathway?
This system carries crude touch, temperature and pain
sensation.
60. Enumerate the types of lemniscus.
It is of 4 types:
• Spinal lemniscus: Formed by STT in medulla
oblangata.
• Lateral lemniscus: Formed by fibers carrying
sensations of hearing from cochlear nuclei to inferior
colliculus and medial geniculate body.
• Medial lemniscus: Formed by fibers arising from N.
gracilis and N. cuneatus of medula.
• Trigeminal Lemniscus: Formed by fibers from sensory
nuclei of trigeminal nerve which carries general
sensation from head, neck, eyeball, face, mouth, ears.
61. Name the sensory tracts (ascending tracts) passing
through dorsal white column of spinal cord.
Tracts in dorsal (Posterior) white column
• Fasciculus Gracilis (Tract of Goll)
• Fasciculus cuneatus (Tract of Burdach).
62. Name the sensory tracts passing through lateral
white column of spinal cord.
Tracts in lateral white column.
• Lateral spinothalamic tract—carries pain and
temperature sensation
• Ventral spinocerebellar tract—carries sub conscious
kinaesthetic impulses
• Dorsal spinocerebellar tract—carries nonsensory
impulse, i.e. subconscious kinesthetic sensation.
• Spinotectal tract—for spinovisual reflex
• Spinoreticular tract—for consciousness
• Spinoolivary tract—proprioceptive impulse.
63. Name the sensory tracts passing through ventral
white column of spinal cord.
Tracts in ventral white column:
166 VIVA VOCE IN PHYSIOLOGY
Ventral spinothalamic tract—carries crude touch
sensation.
64. What is Dermatomal rule?
Pain is usually referred to a structure that develops from
the same segment during the embryonic development.
This principle is known as dermatomal rule.
65. What do you mean by upper motor neurons and
lower motor neurons?
The pyramidal cells and there tracts constitute the upper
motor neurons whereas the spinal and cranial motor
neurons which directly innervate the muscles are
collectively called as lower motor neurons.
66. Why pyramidal tracts are so named?
For two reasons as follows:
• They are originated from pyramidal cells of cerebral
cortex.
• They pass through medulla in the form of pyramid.
67. What do you mean by hemiplegia?
The condition characterised by the weakness or paralysis
on the opposite site of the body due to injury to the
pyramidal tracts in the brain (common lesion site is
internal capsule) is known as hemiplegia.
68. What are the main differences between upper and
lower motor neuron lesion?
LMNL
UMNL
a.
Single individual muscle is
affected
Group of muscles are affected.
b.
Flaccid type of muscle
paralysis due to
hypotonia
Spastic type of muscle paralysis
due to hypertonia
c.
Disuse atropy of muscle
takes place
Not severe
Contd...
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Contd...
d.
All reflexes are absent as
motor pathway is damaged.
Deep reflexes are hyperactive due
increased γ motor activity and
some superficial reflexes like
abdominal, cremastric reflexes
are lost.
e.
Babinski’s sign is negative
It is positive.
69. What are hypertonia, hypotonia, spasticity and
rigidity? What are their causes?
• Hypertonia: It is a state of increase muscle tone in the
body. It occurs in lesion of UMN and extrapyramidal
lesions.
• Hypotonia: It is a state of decrease tone of muscle. It
is due to lesion of lower motor neuron (corticospinal)
and cerebellar lesions.
• Spasticity: It is the state of hypertonia resulting from
lesion of corticospinal system.
• Rigidity: It is the state of rigidity results from basal
ganglion disease and is also called as extrapyramidal
rigidity.
70. What do you mean by epicretic and protopathic
sensations?
Epicretic:
• Mild or light sensations like fine touch, tactile
localisation, tactile discrimination temperature range
of 25-40oC, etc. are known as epicretic sensation.
• These sensations are perceived accurately.
Protopathic sensations:
• Crude sensations like pressure, pain and temperature
range above 40oC and below 25oC.
71. Which part of spinal cord contains cell body of
nerve fiber and which part contains axons of nerve
fiber?
Gray matter contains cell bodies and white matter
contains axons of nerve fiber.
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72. What do you mean by Charcot’s joint?
Swollen painless knee joint in Tabes dorsalis patient is
known as Charcot’s joint.
73. Name the descending tracts and give an account
of each of their function.
Descending tracts of the spinal cord are formed by motor
fibers originating from brain. These are of 2 types:
A. Pyramidal tracts—Directly from motor cortex to spinal
motor neurons
B. Extrapyramidal tracts—From motor cortex to spinal
motor neurons via subcortical nuclei.
A. Pyramidal tracts:
Examples:
(i) Corticospinal tract—Motor fibers of cerebral cortex
to ventral horn cell of spinal cord constitute
corticospinal tract. It is of again 2 types:
• Lateral corticospinal or crossed/indirect
pyramidal tract
• Anterior corticospinal or uncrossed/direct
pyramidal tract.
(ii) Corticobulbar tract—Motor fiber's originating from
cerebral cortex, when terminate in brainstem
structure is known as corticobulbar tract.
B. Extrapyramidal tracts:
• Rubrospinal tract
• Reticulospinal tract
• Vestibulospinal tract
• Tectospinal tract
• Olivospinal tract.
74. What are the chemical transmitters at autonomic
nervous systems?
• In both sympathetic and parasympathetic preganglionic neurons, neurotransmitter is ACh.
• In sympathetic post-ganglionic neurons, neurotransmitter is norepinephrine.
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CENTRAL NERVOUS SYSTEM 169
In parasympathetic post-ganglionic neurons
neurotransmitter is ACh mainly.
75. What are the main levels of integration for following
functions?
Control of spinal reflex—spinal cord.
Regulation of heart rate, respiration rate and antigravity
reflexes—medulla
Regulation of righting reflex—midbrain
Regulation of locomotor reflex—midbrain and thalamus.
Emotional function—hypothalamus and limbic system.
Initiation of voluntary movements, memory, emotion,
conditioned reflex—cerebral cortex.
76. What do you mean by righting reflex?
It is a chain of reaction following one another in an orderly
sequence to maintain normal standing position and keep
the head upright.
77. What is decerebrate rigidity and what is its relation
to γ rigidity?
Transection of the midbrain in between superior and
inferior colliculi in animals results increased muscle tone
in extensor group of muscles called decerebrate rigidity.
This type of rigidity occurs due to increase of γ motor
discharge because of withdrawal of inhibitory
extrapyramidal discharge. Besides this, there is also
facilitatory discharge from descending facilitatory reticular
projection to γ motor neuron. This is why this type of rigidity
is called as γ rigidity.
78. What do you mean by reticular formation?
It is those parts of the brainstem (medulla, pons and
mid-brain) which are characterised by an interlacing
network of fiber bundles. It is composed of more than 50
nuclear masses which together constitute the reticular
formation.
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79. Why reticular formation is absolutely essential for
life?
The reasons are as follows:
• Some RF neurons act as an integration center of
some important physiological function, e.g. cardiovascular and respiratory function, swallowing, etc.
• It receives and integrates information from all regions
in the CNS.
80. How does cerebellum is connected with brainstem?
By means of 3 peduncles as follows:
• To the medulla by inferior cerebellar peduncle.
• To the pons by middle cerebellar peduncle.
• To the midbrain by superior cerebellar penduncle.
81. What do you mean by climbing fiber and mossy
fiber?
Both are the afferent fibers of cerebellar cortex. Climbing
fibers originate from cells in inferior olivary nucleus and
establish one to one connection with Purkinje cells to
excite it. It also gives some collaterals to Golgi cells to
excite it whereas, mossy fibers are axon of spinocerebellar
vestibulo-cerebellar, reticulo-cortico-ponto-cerebellar
tracts and connected with many granule cells in a series
of moss-like glomeruli.
82. Give a account of nerve fibers present in white
matter of cerebral cortex.
White matter consists of mainly myelinated fibers arising
from the cells of gray matter and coming from other areas
of CNS. There are 3 types of fibers forming white matter:
• Association fiber—Connects the neurons of different
parts of cerebrum of same side.
• Commissural fiber—Connects corresponding areas
of cerebral hemsiphere of two sides, e.g: Corpus
callosum.
• Projection fiber—Connects cerebral cortex with
brainstem structures and spinal cord.
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83. What do you mean by Frontal lobe syndrome?
Injury or ablation of frontal lobe results frontal lobe
syndrome which has following symptoms:
• Lack of concentration and lack of fixing attention.
• Person loses the ability to solve problem
• Lack of initiation and difficulty in planning.
• Emotional instability
• Loss of moral and social sense
• Loss of recent memory
• Hyperphagia, slight tremor, etc.
84. What do you mean by adiadochokinesis?
Due to cerebellar lesion, patient is unable to carry out
alternate and opposite movements rapidly. This is known
as adiadochokinesis.
85. What are the voluntary disturbances of cerebellar
lesion?
• Asthenia, i.e. feeble movement.
• Ataxia, i.e. inco-ordination of movement.
• Asynergia, i.e. lack of co-ordination between
protogonists, antagonists and synergists muscle.
• Dysmetria, i.e.the movement is poorly carried out in
direction, range and force.
• Intention tremor
• Drunken gait
• Slow and lalling (like a baby) speech.
86. What is Charcot’s triad?
It is a syndrome characterised by nystagmus, intention
tremor and lalling speech due to disturbances of
cerebellar connection with brainstem which generaly
occurs during disseminated sclerosis.
87. Name two cerebellar function tests.
These are finger nose test, walking along a straight line,
testing of muscle tone.
88. What is metathalamus and epithalamus?
Medial and lateral geniculate bodies are collectively known
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as metathalamus and the part of thalamus which is
connected with olfactory system like pineal body and
Hebenular complex is called as epithalamus.
89. What are the main waves of EEG and their
characteristic features?
Mainly four waves α, β, θ and δ.
• α wave: Moderate frequency with high amplitude
obtained in inattentive brain or drowsiness or light
sleep with closed eyes only.
• β wave: High frequency with low amplitude wave
obtained during mental activity or arousal state.
• θ wave: Low frequency and low amplitude wave
generally obtained in children of below 5 years old.
• δ wave: Low frequency with high amplitude (voltage)
wave commonly occurs in early childhood during
waking hours and mainly adults during deep sleep.
90. What is Kluver Bucy Syndrome?
It is due to bilateral destruction of temporal lobe (in
animal) along with amygdaloid nucleus and uncus (in
human) which is charecterised by-Speech disturbances
(Aphasia), Auditory disturbances, Disturbances in smell
and taste, Dreamy state and Visual hallucination.
91. What is Papez circuit? What is it’s importance?
Prefrontal lobe forms a closed circuit connecting with
thalamus, hypothalmus and hippocampus called as
Papez circuit which is responsible for resting EEG, genesis
and control of emotion and memory.
92. What is Thalamic syndrome? What do you mean by
thalamic phantom limb?
Thalamic lesion leads Thalamic syndrome.
Causes: Mostly due to blockade of one of the arteries
supplying thalamus.
Symptoms/Features:
• Thalamic pain—spontaneous and often excessive
pain on opposite side of the body which may be
aroused by simply light touch or by cold.
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•
•
•
•
•
CENTRAL NERVOUS SYSTEM 173
Loss of all sensations.
Asteriognosis—inability to recognise a known object
by handling with closed eyes.
Ataxia—in co-ordination of voluntary movement due
to loss of kinesthetic sensation.
Thalamic phantom limb—inability to locate the
position of limb with closed eyes
Thalamic hand—in some patients the contralateral
hand is held in an abnormal posture, i.e. moderate
flexion at wrist joint with hyperextension of all fingers.
Abnormal involuntary motor movements like:
– Chorea, i.e. quick jerky movements
– Intention tremor
– Athetosis, i.e. slow writhing and twisting
movements
93. Give an account of hyperkinetic syndrome of basal
ganglia.
Hyperkinetic syndrome may be due to:
• Lesion of Caudate N and Putamen: It is characterised
by purposeless involuntary jerky movements which
do not follow definite pattern known as Chorea.
• Lesion of Globus Pallidus: It is characterised by slow
confluent writhing or worm like movement called
Atheosis.
94. What is parkinsonism?
Lesion of Substantia Nigra results Parkinsonism.
Cause: Decrease secretion of dopamine which results
abnormal excitation of basal ganglia.
Physiological basis: Dopamine secreted in caudate
nucleus and putamen by substantia nigra is inhibitory.
Therefore, destruction of substantia nigra causes
withdrawal of inhibition of these structures which in turn
become overactive and cause continuous output of
excitatory signal to the corticospinal motor system.
174 VIVA VOCE IN PHYSIOLOGY
Features:
• Lead pipe or Cogwheel rigidity—due to increase in
muscle tone.
• Static tremors—Tremor at rest and disappears
during voluntary activity due to oscillatory continuous
discharge of pyramidal system by a closed circuit
through basal ganglia.
• Akinesis—It is difficulty in initiation or starting movement
due to rigidity of the muscles so the automatic associated
movements do not occur resulting:
• Mask like face (no facial expression)
• Statue like posture.
• Festinant Gait—The person walks with short quick
steps with the body bent forwards as if the person is
trying to prevent himself from falling.
95. Differentiate REM and NREM sleep.
Slow wave sleep or orthodox or Non rapid eye movement
(NREM) sleep:
• It occupies 70% of sleep period.
• Lasts for every 70-90 min and interrupted by 10-20
mins of REM sleep.
• Produced by absence of desynchronising activity via RAS.
• EEG shows slow, synchronised theta and delta waves.
Rapid eye movement (REM) or paradoxical or fast wave
or dream sleep:
• Rapid to and fro movement of eye ball occurs.
• HR and respiratory rate becomes irregular.
• Occasional muscle twitch can take place.
• Difficult to wake an individual if he is in this phase of
sleep.
• Dreams are more vivid.
• Shows fast desynchronised waves.
96. Enumerate the site of memory storage.
It is randomly stored in the brain. However important sites
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are-Hippocampus of limbic system and Wernick’s area
of cerebral cortex.
97. What do you mean by amnesia, retrograde amnesia
and anterograde amnesia?
• Amnesia : It is defined as the inability to recall the
memories of recent events.
• Retrograde amnesia : It is inability to recall memories
from the distant past.
• Anterograde amnesia : It is the inability of the person
to establish new long-term memories of those types
of information that are basis of intelligence. It occurs
due to lesion in hippocampus.
98. What is pure motor apnasia?
Loss of articular speech without mental confusion is pure
motor apnasia.
99. What is pure word blindness?
Inability to recognise meaning of written or printed words
is known as pure word blindness. In this case patient is
unable to read.
100. What is agrolphia?
It is the inability to write.
101. What is pure word deafness?
It is failure to recognise spoken speech with no other
defect of speech or intelligence.
102. What is dysarthria?
Speech disturbance due to defects in excitomotor areas
in cortex, pyramidal tract, cranial nuclei, etc. is known as
dysarthria.
103. What is Wernicke’s area, Dejerine area and sensory
speech center?
• Wernicke’s area is auditory speech center located in
the region at the posterior end of the superior temporal
gyrus in the dominant hemisphere and is concerned
with comprehension, i.e. interpretation and
understanding of auditory information.
176 VIVA VOCE IN PHYSIOLOGY
•
Dejerine area is visual speech center located in the
angular gyrus behind Wernicke’s area. These two
areas are collectively known as Sensory speech area.
104. What are the motor speech areas?
It includes Broca’s area (area 44) and Exner’s area (motor
writing center). Broca’s area is located in the inferior
frontal gyrus in the region of the anterior and ascending
rami of the lateral sulcus in the dominant hemisphere
whereas Exner’s area is located in the middle frontal gyrus
in the dominant hemisphere.
105. Enumerate the origin of sympathetic and parasympathetic nervous system?
Origin of sympathetic: Lateral gray horn of thoracic and
lumber (T1- L2) segments of spinal cord.
Origin of parasympathetic: Cranio-sacral
• Cranial:
- Oculomotor (IIIrd nerve) from midbrain (Tectum)
level.
- Facial (VII nerve), glossopharyngeal (IX nerve)
and vagus (Xth nerve) from bulbar level of brain.
• Sacral: 2nd to 4th sacral segments of spinal cord.
106. Enumerate the spinal and cranial nerves.
i.
ii.
iii.
iv.
v.
Spinal nerves
Cranial nerves
8 pairs of cervical (C8)
12 pairs of thoracic (T12)
5 pairs of lumbar (L5)
5 pairs of sacral (S5)
1 pair of coccygeal (Cg1)
i.
ii.
iii.
iv.
v.
vi.
vii.
viii.
ix.
x.
xi.
xii.
Olfactory (Afferent)
Optic (Afferent)
Oculomotor (mixed)
Trochlear (mixed)
Trigeminal (mixed)
Abducens (mixed)
Facial (mixed)
Vestibulo-cochlear (Afferent)
Glossopharyngeal (mixed)
Vagus (mixed)
Spinal Accessory (efferent)
Hypoglossal (efferent)
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CENTRAL NERVOUS SYSTEM 177
107. What is BBB? What are its importance?
The entry of some substances from the blood to the brain
ECF is restricted due to barrier offered by the walls of
the capillaries supplying the brain. This barrier is known
as Blood-Brain Barrier (BBB).
108. How can you collect CSF?
If required CSF can be collected by lumbar puncture
technique. In this technique a needle is inserted in
between 3rd and 4th lumbar spinous processes into the
subarachnoid space within the vertebral canal and CSF
is sucked-outside. In this process there is no risk of
damaging the spinal cord as it ends at the level of first
lumbar vertebra.
109. What is the average volume and pressure of CSF?
Volume—100-110 ml
Pressure—100-110 mm of water.
110. What is normal glucose level in CSF?
50-70 mg%.
111. What is the normal cerebral blood flow?
750 ml/min.
178 VIVA IN MEDICAL PHYSIOLOGY
1.10
Special Senses
1. Name the layers of the eyes?
• Sclera (outer fibrous protective layer).
• Choroid (middle vascular layer).
• Retina (inner nervous layer).
2. Colour of the eye is colour of what structure of eye?
What is the function of the pigment present in it?
It is iris and pigmented layer of iris absorbs the extra
amount of light.
3. What is blind spot and yellow spot?
The small area of retina where optic nerve leaves the
eye is called as optic disc. It does not contain any light
sensitive photoreceptor and that is why vision is not
possible over this area. This spot is called as blind spot.
At the posterior pole of the eye there is yellowish
pigmented spot which marks the location of fovea centralis
where rods are not present, only cones are densely
packed. This spot is called as yellow spot or macula lutea
which is also the point of greatest visual acuity.
4. Name the refractive media of the eye?
They are cornea, aqueous humour, lens, vitreous
humour.
5. What is the function of iris in the eye?
It restricts the peripheral light rays and also prevents
spherical abberations. It also controls the intensity of light
falling on the eye.
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SPECIAL SENSES 179
6. What are the functions of lacrimal gland secretion?
These are: It lubricates the conjunctiva, its lysozymes
have bacteriocidal action, helps to remove the foreign
body from the eye through overflow.
7. How is aqueous humour formed?
It is formed by ciliary body and anterior surface of iris by
dialysis of crystaloids.
8. What are the functions of aqueous humour?
• It maintains normal intraocular pressure required for
normal refraction.
• It provides nutritions to the cornea and lens.
9. What is the function of vitreous humour and where
does it present?
• It prevents the walls of eyeball from collapse.
• It also maintains intraocular pressure.
It is present in the interior of the eyeball between the
lens and the retina.
10. Where does aqueous humour present?
It is present in the anterior and posterior chamber of the
eye.
11. What is the physiological and clinical importance
of Canal of Schlemm?
Aqueous humour once formed from the ciliary process
passes from the posterior chamber then via pupil enters
into anterior chamber which then passes into the
intrascleral venous plexus through canal of Schlemm,
thereby this canal helps to drainage the aqueous humour
continuously secreting from cilliary body. Blockade of the
canal of Schlemm leads to increase intraocular pressure
above 80 mm Hg resulting pain and degeneration of blood
vessels of retina and choroid. This condition is known as
glaucoma.
180 VIVA IN MEDICAL PHYSIOLOGY
12. Define the term anopia, homonymous hemianopia,
heteronymous hemianopia, scotoma.
• Anopia—It is the complete loss of visual field in an
eye (Fig. 1.10.1A)
• Hemianopia—Refers to the blindness of half of the
visual field (Fig. 1.10.1B)
• Homonymous hemianopia—It refers to the loss of
field of vision of same halves in two eyes (Fig. 1.10.1B)
• Heteronymous hemianopia—When different halves
of field of vision in two eye are lost (Fig. 1.10.1C).
Figs 1.10.1A to C: Types of hemianopia
•
Scotoma—Loss of vision in an eye which is confined
to the center of the visual field.
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SPECIAL SENSES 181
13. What type of anopia you will see in case of lesion
of following structure?
a. Optic nerve—complete anopia
b. Optic chiasma—heteronymous hemianopia
c. Optic tract—homonymous hemianopia
d. Lateral geniculate body—homonymous hemianopia
e. Occipital cortex—quadrantanopia
f. Area 18/19—visual agnosia.
14. What is Wernicke pupillary reflex?
In case of partial damage of light reflex fibers, when light
is focused on the blind part of retina light reflex is lost
and if light is focused on the sound retinal part light reflex
persists. This reflex is known as Wernicke pupillary reflex.
15. What do you mean by macular sparing?
In case of occipital cortex lesion, oftenly there is a loss of
peripheral vision with normal and complete macular vision
called as macular sparing.
16. Define visual acuity.
It is the shortest distance by which two lines can be
separated by the eyes. It is expressed in visual angle.
17. What do you mean by direct and indirect reflex?
Focusing of light in one eye leads to constriction of the
pupil of that particular eye which is known as direct light
reflex and the same event also results constriction of pupil
of other eye which is known as indirect or consensual
light reflex.
18. Define accommodation.
It is the ability of the eye to focus an object at varying
distances by changing the curvature of anterior surface
of the lens.
19. What is accommodation reflex or near response?
When an individual looks at near object to focus the
image of an object properly, three events take place—
contraction of ciliary muscles, constrictions of pupils and
182 VIVA IN MEDICAL PHYSIOLOGY
convergence of visual axis. This reflex is known as
accommodation reflex.
20. What is the range of accommodation?
• Near point is 9-10 cm at age of 10 years.
• Far point is 6 meter from the eye.
21. What is the amplitude of accommodation?
It is 14 diopters.
22. What is Argyll Robertson pupil and reverse Argyll
Robertson pupil?
In case of lesion in aqueduct and superior colliculi, there
is a loss of light reflex keeping the convergence
accommodation reflex intact. This type of pupil is referred
to as Argyll Robertson pupil. Where as due to the lesion
in frontal lobe (bilaterally) or damage of its descending
fibers to III nerve nucleus pupillary constriction in response
to light is present but accommodation is lost. This is known
as reverse Argyll Robertson pupil.
23. What do you mean by spherical and chromatic
aberration?
• Spherical aberration is due to difference in refractive
indices of central and peripheral parts of the lens and
usually reduced with the help of iris.
• Chromatic aberration is due to different wave lengths
of coloured rays.
24. What is presbyopia?
Decreased ability of the eye to accommodate due to aging
is called as presbyopia.
25. What is cataract?
UV irradiation results agglutination of iris protein and its
coagulation in the presence of Ca+2 making the lens hard,
opaque and swollen which is called as cataract.
26. What is emmetropia?
It is the normal refractory function of the eyes.
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SPECIAL SENSES 183
27. What is aetropia?
It is the deviation from normal refractory state of the eyes.
28. What is myopia, hypermetropia and astigmatism?
How these are corrected?
• Myopia—It is the condition in which distant objects
are not seen clearly as parallel rays of light from
distant objects are focused in front of retina either
due to increase length of eye ball or increase
refractory power of lens. It can be corrected by
concave lens.
• Hypermetropia—It is the condition in which near
objects are not seen clearly as parallel light rays from
objects are focused behind the retina due to
shortening of eyeball or diminishing of refractive power
of lens. It is corrected with the help of convex lens.
• Astigmatism—It is an error of vision in which the light
rays are not brought to a point focus on the retina
resulting blurring of vision. It is corrected with
cylindrical lens placed in such a way so that the
refraction from all the meridians become equal.
29. What is photopic, scotopic and mesopic vision?
• Photopic—It is daylight vision due to cone receptor.
• Scotopic—It is dim light vision and a function of rods.
• Mesopic—It is a full moon night vision where reading
becomes difficult.
30. What do you mean by transition zone?
Between 0.01 to 1.0 mÅ function of cones overlap with
rods. This zone is called as transition zone.
31. What do you mean by Purkinje shift or Purkinje
phenomenon?
The shifting of sensitivity of eye in response to change
of light intensity from photopic to scotopic vision is known
as Purkinje shift. It is seen normally towards the evening.
184 VIVA IN MEDICAL PHYSIOLOGY
32. What is dark adaptation?
When an individual passes from a bright light to dark his
vision first gets poor but then gradually improves. This is
the function of rods in which rhodopsin is regenerated in
dark. This phenomenon is known as dark adaptation.
33. What is nyclopia?
In severe vit. A deficiency the function of rods is disturbed
and so the process of dark adaptation is practically
absent. This condition is characterised as nyclopia or
night blindness.
34. What is colour blindness? How they can be
diagnosed?
It is the inability to differentiate the colours. It can be
diagnosed by using Edridge Green and Red lantern and
with Ishihara chart.
35. What do you mean by monochromats, dichromats
and trichromats?
• Monochromats—Individuals with only one cone
system present.
• Dichromats—Individuals with only two cone system
present thus they have either protanopia (red
blindness) or deuterapanopia (Green blindness) or
tritanopia (Blue blindness).
• Trichromats—Individuals with normal colour vision or
they have all the Red, Green, and Blue coloured cone
system but one may be weak is called trichromats.
36. What is red-green blindness?
If either red or green or both of these cones are missing
from the retina in a person, that person can’t distinguish
red colour from green colour. This condition is known as
red-green blindness.
37. What is meant by Deuteranomaly, Protanomaly and
Tritanomaly?
• Weakness of green colour is deuteranomaly.
• Weakness of red colour is protanomaly.
• Weakness of blue colour is tritanomaly.
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SPECIAL SENSES 185
38. What is glaucoma?
Any obstruction of the outflow of aqueous humor results
increased intraocular pressure which is known as
glaucoma.
39. What is electro-olfactogram?
When an odorous molecule gets absorb in the olfactory
mucosa a monophasic negative potential is recorded
which lasts for 4-6 secs. This recorded electrical changes
is known as electro-olfactogram.
40. What is the function of tympanic membrane?
• It acts as a pressure receiver.
• It acts as a resonator and starts vibrating freely when
the sound waves strike.
• It helps in impedance matching device.
41. What are the components of impedance matching
devices in ear? How impedance is matched?
Tympanic membrane, ear ossicles and oval window are
components of impedance matching device. The
impedance is matched by following mechanism:
• The high ratio of surface area of tympanic membrane
to oval window increases pressure 17 times.
• The lever system of ear ossicles also increases the
sound intensity by 1.2–1.3 times.
42. What is Eustachian tube and what is its importance?
It connects the middle ear cavity with the pharynx.
Normally its pharyngeal opening is closed but opens
during act of swallowing, chewing or yawning and thereby
helps the air to enter into middle ear. Therefore it serves
to equalise the pressure on the two sides of tympanic
membrane when atmospheric pressure changes.
43. Why does there is pain in ear and even loss of
hearing in sore throat?
Due to infection during sore throat there is an inflammation
occurs in pharynx causing closure of pharyngo-tympanic
tube. Thus middle ear cavity becomes a closed cavity
186 VIVA IN MEDICAL PHYSIOLOGY
due to inability to open eustachian tube. When the air
within the middle ear gets absorbed, its pressure
decreases resulting inward bulging of tympanic
membrane that causes pain sensation and in severe
cases there may be rupture of tympanic membrane
resulting loss of hearing.
44. Name the muscles present in middle ear? What are
their functions?
• Tensor tympani—attached to the neck of malleus.
• Stapedius—attached to the neck of stapes.
In response to loud sounds, these muscles contract
reflexly → decrease the amplitude of vibration of TM in
response to loud sound →cause less pressure change
in cochlear fluid → Protect the internal ear from being
damaged. This protective mechanism is called as acaustic
reflex or tympanic reflex.
45. Name different structures in internal ear.
Vestibule or Saccule, Cochlea and Semicircular canal.
46. Name different cavities in cochlea and the
respective type of fluids.
• Scala vestibuli—Contains perilymph.
• Scala media—Contains endolymph.
• Scala tympani—Contains perilymph.
47. What is helicotrema?
Scala tympani and scala vestibuli communicate at the
apex by a small opening called as helicotrema.
48. What is the range of sound frequencies audible to
the human ear?
20-20,000 cycles per second.
49. Which part of cochlea is affected by low frequency
and which part is affected by high frequency of
sound?
Apex of the cochlea is affected by low frequency and
base of the cochlea is affected by high frequency sound.
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SPECIAL SENSES 187
50. What is cortico-lymphatic, and endo-cochlear
potential?
• An electrical potential of about 180 mv exists all the
time between endolymph and perilymph with positivity
inside the scala media and negativity outside. This is
called as endocochlear potential which is generated
by the continual transport of K+ ions into scala media
by the stria vascularis.
• The potential difference between supporting cells or
haircells and perilymph during resting condition is
known as corticolymphatic potential.
51. What are the types of deafness and their causes?
• Conductive deafness: Causes-accumulation of ear wax
perforation of tympanic membrane (otitis media
inflammation of middle ear), otosclerosis, (rigidity of
ear ossicles).
• Nerve deafness: Causes-damage of hair cells in
response to loud sound, injury to VIII nerve, tumour of
VIII nerve, vascular damage in medulla, degeneration
of VIII nerve due to streptomycin injection or during
measles, meningitis.
52. What is tinnitus?
It is a ringing sensation in the ears by irritative stimulation
of either the internal ear or the auditory nerve.
53. Name the receptor for smell sensation.
Olfactory neuroepithelium.
54. What is anosmia?
It is the complete loss of smell sensation.
55. Man is macrosomotic or microsmotic?
Microsmotic as their smell sensation is not well developed
like that of dog or rabbit.
56. Where are the taste buds lie?
• On the surface of fungiform papillae.
• In the grooves of foliate papillae.
• At vallate papillae present at back of tongue.
188 VIVA IN MEDICAL PHYSIOLOGY
57. What are the types of sensation and what is due
to?
• Sour—Due to presence of H+ in the substance.
• Salt—Due to the presence of Na+.
• Bitter—Due to presence of many chemicals like
quinine, nicotine, caffeine, etc.
• Sweet—Due to organic compounds.
58. What do you mean by ageusia?
It is the absence of taste sensation.
ENDOCRINAL SYSTEM 189
SECTION I : THEORY VIVA
1.11
Endocrinal System
1. Define endocrine gland.
It is a ductless gland which secretes the chemical
substances known as hormones directly into blood.
2. Define hormone.
These are secretory products of ductless glands released
directly into the circulation in small amounts in response
to specific stimulus and produce response to the target
cell/organ.
3. What are the differences between hormone and
vitamins?
Parameters
Hormone
Vitamin
1.
Nutritive role
Not present
Present
2.
Incorporation as a structural No
moiety in another molecule
Yes
4. Classify the hormones citing examples of each.
Hormones are classified into 3 major classes:
• Steroids—Like adrenocortical hormones, sex
hormones and vit-D3
• Proteins and polypeptides—Like anterior and posterior
pituitary hormones, hypothalamic hormones,
parathyroid hormones, calcitonin, insulin, glucagon,
gastrin, secretin and angiotensin.
• Amino acid derivatives—Epinephrine, norepinephrine,
thyroxine.
190 VIVA IN MEDICAL PHYSIOLOGY
5. Name the hormones secreted by following organs.
• Hypothalamus—Releasing hormones, like GnRH,
TRH, CRH, etc.
• Ant. pituitary—TSH, ACTH, GH, FSH, LH, prolactin.
• Post. pituitary—ADH and oxytocin.
• Thyroid—thyroxin,
Tri-iodothyronine
and
thyrocalcitonin
• Parathyroid—Parathormone (PTH).
• Adrenal cortex—Cortisol, corticosterone, aldosterone,
androgens, estrogens and progesterone.
• Adrenal medulla—Adrenaline and noradrenaline.
• Testis—Testosterone.
• Ovary—Estrogen and progesterone.
• Placenta—HCG, estrogen, progesterone, HPL.
• GIT—Gastrin, secretin, motilin, substance-P,
cholecystokinin.
• Kidney—Erythropoietin, Vit-D3, medullipin.
• Heart—ANF (Atrial natriuretic factor).
6. What do you mean by long loop feedback, short
loop feedback and ultrashort loop feedback?
• When peripheral gland hormones or substances from
tissue metabolism exert negative feedback control on
both the hypothalamus and anterior pituitary hormones,
it is known as long loop feedback mechanism.
• When anterior pituitary hormones exert the negative
feedback control over the synthesis and release of
hypothalamic releasing hormones, it is known as short
loop feedback mechanism.
• When hypothalamic releasing hormones after its
secretion inhibit their further own synthesis and
release it is known as ultrashort loop.
7. What do you mean by hypothalamo–hypophyseal
portal vessels and hypothalamo-hypophyseal fiber
tract?
• The glandular part of pituitary gland has vascular
connections with hypothalamus through a set of portal
SECTION I : THEORY VIVA
•
ENDOCRINAL SYSTEM 191
vessels through which hypothalamic releasing
hormones enter into adenohypophysis to regulate their
secretion. These portal blood vessels are known as
hypothalamo-hypophyseal portal tract.
Whereas the neurohypophysis is connected with
hypothalamus by hypothalamo-hypophyseal fiber
tracts from supraoptic and paraventricular nuclei of
anterior hypothalamus. These tracts are known as
hypothalamo-hypophyseal fiber tract through which
those above mentioned nuclei pass the oxytocin and
vasopressin into posterior pituitary gland for storage.
8. How do you classify anterior pituitary gland cells
histologically.
9. Differentiate somatotropin, somatostatin and
somatomedins.
Somatotropin is the growth hormone (GH) secreted by
somatotroph cells of anterior pituitary. Somatostatin is
the growth hormone inhibiting hormone released from
hypothalamus and also found in nerve endings of brain,
cells of antrum of stomach and in cells of pancreatic islets
of Langerhans. Somatomedins are growth factors,
synthesised and released from liver (mainly), kidneys,
muscle, etc. in response to growth hormones and play
role on skeletal growth mainly.
192 VIVA IN MEDICAL PHYSIOLOGY
10. What is the normal plasma level of growth
hormones?
• 4 mµg/ml in adult
• 7 mµg/ ml in children.
11. Why the GH is known as protein sparer?
It decreases protein and amino acid catabolism by
increasing fat catabolism. This is why it is known as
“protein sparer”.
12. Why the growth stops after adolescence?
At the time of adolescence there is fusion between shaft
and each end of epiphysis and thus GH can not promote
the increase of growth of long bone at epiphyseal end
plate. This results no growth of long bones after
adolescence.
13. Lactating mother has less risk to be pregnant –Why?
During and after pregnancy high PRL level in blood
inhibits LH secretion → unovulation → No further
pregnancy as long as high PRL level is maintained.
14. What is gigantism due to?
It is due to overproduction of GH during adolescence,
i.e. before fusion of epiphyseal plate and is characterised
by excessive growth of long bone.
15. What is the cause of acromegaly?
It is usually due to tumour of acidophilic cell of anterior
pituitary with hyperactivity of growth hormone in adults,
i.e. after epiphyseal closure.
16. What are the effects of acromegaly and its
physiological basis?
Following are the characteristics of acromegaly:
• Acromegalic facies, i.e. broad and thick nose, thick
skin, prominent brow and coarsening of facial features.
These are due to proliferation of connective tissue
that leads to edema and also enlargement of frontal,
mastoid, ethmoid and maxillary sinuses (for promiment
brow).
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•
•
ENDOCRINAL SYSTEM 193
Kyphosis—Due to periosteal growth of vertebrae
causes bowing of spine.
Acral parts—periosteal growth of metacarpals and
metatarsals.
Hypertrophy of body soft tissue like heart
(cardiomegaly), liver (hepatomegaly), etc.
17. What is dwarfism due to?
It is due to hypofunction of GH secreting anterior pituitary
glandular cells.
18. What is Laurence Moon Biddle syndrome?
It has following characteristics:
• Physical and mental retardation in growth
• Subnormal intelligence.
• Infantile gonads.
• Obesity with polydactylism
• Retinitis pigmentosa
All these are due to hypofunction of pituitary gland as a
result of tumour of chromophobe cells or lesions in
hypothalamus in the young.
19. What is Simmond’s disease?
It is due to panhypopituitarism in adults due to
degeneration of the whole anterior pituitary gland
resulting loss of weight, general emaciation, anaemia,
low BMR, low body temperature, atrophy of gonads, etc.
20. What do you know about MSH?
Melanocyte stimulating hormone is secreted by
intermediate lobe of pituitary gland and is responsible
for melanin formation, i.e. pigmentation of skin in human.
21. Name the nuclei secreting ADH and Oxytocin?
• Supraoptic nuclei
– ADH
• Paraventricular nuclei
– Oxytocin.
22. What is Neurophysin I and II?
Neurophysin I is a carrier protein that helps to transport
oxytocin from hypothalamus to posterior lobe of pituitary
194 VIVA IN MEDICAL PHYSIOLOGY
gland for storage, through hypothalamo–hypophyseal
fiber tract. Neurophysin II is also a carrier protein for the
intraneuronal transport of ADH from hypothalamus to
posterior pituitary.
23. What do you mean by syndrome of inappropriate
ADH secretion (SIADH)?
It is due to excessive or inappropriate secretion of ADH
resulting—
• Increase of blood volume and ECF volume.
• Hypernatremia and Hypernatriurea.
• Shift of water to ICF that results water intoxication
called overhydration or dilution syndrome.
24. What is the normal concentration of iodine in
blood?
It is 0.5–1 µg%.
25. What is the normal level of protein bound iodide
(PBI) in blood?
It is 4-8 µg%.
26. What is the normal blood thyroxin level?
It is 9 µg%.
27. What is the plasma level of T3 and T4 hormone?
• T3- 0.1 µg m%
• T4 - 3-8 µg m%.
28. How TSH increases the thyroid hormone secretion?
TSH increases the thyroid hormone secretion by following
ways:
• Increased proteolysis of thyroglobulin → increase
release of thyroid hormones.
• Increasing activity of Iodide pump
• Increasing iodination and coupling reaction
• Increasing size and secretory activity of thyroid cells.
• Increasing number of thyroid cells.
29. What do you mean by thyroglobulin?
It is a glycoprotein synthesised in the thyroid cells and
secreted into the colloid in lumen of thyroid follicle.
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ENDOCRINAL SYSTEM 195
30. What should be the daily intake of I2.
Average 500 µgm.
31. Which one is the most active thyroid hormone T3
or T4?
It is T3 or triiodothyronine. T4 acts as a prohormone, i.e.
precursor of T3.
32. What are the main functions of thyroid hormone?
These are:
• To accelerate the metabolic activity with heat
production.
• To promote growth.
• To ensure normal development of CNS.
33. How is thyroid secretion controlled?
It is controlled by several mechanism as follows:
• By blood level of free T4 and T3 through hypothalamichypophyseal axis (negative feedback)
• Iodine level in blood (autoregulation)
• Environmental temperature
• Adrenaline and gonadal hormones.
34. What are the causes and effect of hypothyroidism?
Causes:
• Failure of normal development of thyroid gland.
• Formation of autoantibody against thyroglobulin.
• Deficiency of iodine.
• Surgical removal of thyroid gland.
Effect: Cretinism in children and myxoedema in adults.
35. What are the causes of hyperthyroidism?
These are:
• Excessive secretion of thyroid hormones.
• Presence of long acting thyroid stimulator (LATS)
substances in blood.
36. What are the signs and symptoms of hyperthyroidism?
These are:
• Exophthalmos expression of patient.
196 VIVA IN MEDICAL PHYSIOLOGY
•
•
•
•
•
•
High BMR.
Rapid pulse and heart rate.
Increase in cardiac output.
Nervous irritability.
Involuntary tremors of hand muscles.
Creatinuria and glucosuria.
37. What do you mean by autoregulation of thyroid?
Iodine content in diet regulates the thyroid hormone
production in the body, i.e. excessive ingestion of iodine
decreases I2 transport to follicular cells whereas I2
deficiency leads to the enlargement of thyroid glands.
Thus normal thyroid hormone secretion is maintained
within the physiological limit without altering the TSH
secretion. This intrinsic control system of thyroid hormone
secretion is known as autoregulation.
38. What is myxoedema, idiot child and myxoedema
madness?
• In hypothyroidism because of decreased catabolism,
there is deposition of mucopolysaccharides like
hyaluronic acid and chondroitin sulphate under the
skin and subcutaneous tissue which then exert osmotic
pressure that causes retention of water and NaCl. This
ultimately leads to dry, coarse and puffy appearance
of skin (non-pitting oedema) called myxoedema.
• Deficiency of T4 after birth upto 2 years in child results
under development of brain producing mental
retardation of child. This is known as idiot child.
• The same cause, i.e. T4 deficiency during adulthood
results loss of all intellectual function, memory and
also slow speech and mental and physical lethergy.
These lead to madness or psychosis known as
myxoedema madness.
39. What are the common clinical conditions of
hyperthyroidism?
Exophthalmic goitre and nodular goitre.
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40. What do you understand by exophthalmos?
It is a characteristic protrusion of the eyeballs from the
orbit seen in patient suffering from exophthalmic goitre.
41. How do you classify goitre?
42. What is the cause of simple goitre (endemic
goitre)?
It is iodine deficiency.
43. What do you suggest to prevent simple goitre in
endemic goitre areas?
It is advised to add potassium or sodium iodide in common
salt in 1:100000 ratio. This ensures daily intake of 200 µg
of iodine to prevent occurrence of simple goitre.
44. What is LATS?
These are thyroid stimulating immunoglobulins that bind
with the receptors on thyroid cell plasma membrane and
displace TSH from its binding sites. Then via cAMP it
acts to cause prolonged action on thyroid gland to
increase formation and release of thyroid hormones and
also increase growth of thyroid gland. These ultimately
result enlargement and hyperplasia of thyroid gland.
45. What is the normal daily requirement of Ca++ and P
and what is their normal blood level?
Substance
Daily requirement
Blood level
Ca++
P
0.8 –1 gm
1-1.4 gm
9-11 mg%
2.5 –4 mg%
198 VIVA IN MEDICAL PHYSIOLOGY
46. Name the hormones regulate Ca++ metabolism and
their source.
• Vitamin D—Diet mainly and also skin by UV radiation.
• PTH—Chief cells of parathyroid gland.
• Calcitonin—Parafollicular cells (C-cells) of thyroid
gland.
47. What are the main actions of PTH?
Its action is mediated through mainly 3 organs as follows:
• In bone: PTH increases the reabsorption of ionised
Ca++ from bone thus raising serum Ca++ ion by
enhancing both osteolytic and osteoclastic activity.
• In kidney:
• It decreases reabsorption of phosphate from PCT
and DCT of kidney and decreases serum
phosphate level.
• It also increases Ca++ reabsorption in DCT, thereby
increase of serum Ca++ concentration.
• It also promotes the conversion of 25 HCC to 1, 25
DHCC in the kidney.
• It increases urinary excretion of Na+, K+ and HCO3¯
and decreases excretion of NH4+, H+.
• On GIT: It increases Ca++ and PO4= reabsorption
through GIT from food.
48. What are the main actions of calcitonin?
Like PTH calcitonin also affects on bone, kidney and GIT
but in opposite direction, i.e. lower plasma Ca++ level.
• On bone:
• Decreases bone resorption process by inhibiting
osteoclastic activity.
• Increases osteoblastic, i.e. bone formation activity
by stimulating synthesis and release of alkaline
phosphatase from the osteoblast.
• On kidney:
• Decreases renal formation of 1-25 DHCC that
decreases plasma calcium level.
• Increases Ca++, Na+, PO4= excretion in urine.
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ENDOCRINAL SYSTEM 199
On GIT:
• Inhibits Ca++ absorption through intestine.
• Increases intestinal secretion of water and
electrolytes.
49. Are the parathyroid glands essential for life? Justify
your answer.
Yes, as their removal will cause the decrease of plasma
Ca++ level in a greater extent thereby there will be spasm
of laryngeal muscles, thoracic muscles and diaphragm
resulting asphyxia and ultimately death.
50. What are the main signs and symptoms of
hypoparathyroidism?
Hypocalcaemia, hyperphosphataemia, increase in blood
pH, neuromuscular hyperirritability causing tetany.
51. What are the common signs present in tetany?
Explain each of them.
• Trousseau’s sign or carpopedal spasm—It is
manifested in the upper limb as flexion at the wrist
and thumb with hyper-extension of remaining fingers
called obsteric hand/accoucheur’s hand or carpopedal
spasm. If this is demonstrated by occluding the blood
supply to a limb through sphygmomanometer cuff, it
is known as Trousseau’s sign.
• Chvostek’s sign—If skin in front of the ear is tapped,
there is contraction or spasm of facial muscle.
• Erb’s sign—It is depicted by the enhanced motor
excitibility of galvanic current.
52. What is laryngeal stridor?
Due to hypoparathyroidism sometimes the laryngeal
muscle becomes spasmatic resulting airways obstruction
and thereby asphyxia and can also result death. This is
known as laryngeal stridor.
53. What are the main characteristics of hyperthyroidism?
These are as follows:
• Weakness, loss of muscle tone, thirst, polyuria,
nousea, vomiting, constipation, etc.
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•
•
•
•
•
•
Kidney stones (Nephrocalcinosis)
Demineralization of bones resulting fragile and
spontaneous fracture in bone with multiple bone cysts
called osteitis fibrosa cystica.
Increase in serum Ca++ upto 22 mg%.
Decrease in serum PO4= below 2.5 mg%
Increase in serum alkaline phosphatase.
Hypercalciuria.
54. Why decreased ionised Ca++ causes neuromuscular
hyperexcitibility?
Decrease plasma Ca ++ causes increase in Na +
permeability and thereby increase in excitability of the
tissue.
55. What do you mean by Osteomalacia, Osteoporosis
and Osteosclerosis?
Osteomalacia is the adult ricket characterised by:
• Decrease in mineral in bone/unit of bone matrix
• Generally limited to females usually after multiple
pregnancy and lactation
Causes:
• Dietary deficiency of vit D
• Malabsorption of Vit -D
• Chronic renal failure
• Inadequate exposure to sun
Characteristic features:
• Bone pain and tenderness
• Fracture may occur
• Proximal myopathy.
• Deformed bone with bowing legs
• Retarded growth
• Thickening of wrists and ankle.
]
]
]
In children
Osteoporosis: It is the clinical condition charecterised
by;
• Increase in all constituents of bone due to increase in
bone resorption and decrease in bone formation.
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ENDOCRINAL SYSTEM 201
•
Causes
- Postmenopausal women (due to low oestrogen
level resulted from increase in sensitivity of PTH
to bone)
- Hyperparathyroidism
- Hyperthyroidism
- Calcium deficiency
Osteosclerosis: Increased calcified bone in patient with
metastatic tumour, lead poisoning and hypothyroidism.
56. Name the layers of adrenal cortex and the hormones
secreting from them.
• Zona glomerulosa—Secretes mineralocorticoids
(Aldosterone).
• Zona fasciculata—Secretes glucocorticoids.
• Zona reticularis—Secretes androgen.
However in human zona fasciculata and zona reticularis
act as a single functional unit synthesising mainly cortisol
(glucocorticoids) and androgens.
57. Are the adrenal cortex essential for life? Justify
your answer.
Yes, as adrenal cortical hormones are essential to
maintain normal metabolic process of cells and also to
control the water and electrolyte balance which are very
much necessary for normal functioning of cells.
58. Which of the layer of adrenal cortex is/are
unaffected by absence of ACTH?
Zona glomerulosa.
59. What are the steroids produced in the body?
• Glucocorticoids—Cortisol, corticosterone, cortisone,
etc.
• Mineralocorticoids—Aldosterone and deoxycortisone.
• Sex steroids—Androgen, estrogen and progesterone.
202 VIVA IN MEDICAL PHYSIOLOGY
60. What is the normal daily secretion and normal
plasma level of cortisol and aldosterone?
Hormones
Daily secretion
Normal plasma level
Cortisol
12-50 mg/day
6-26 µg%
Aldosterone
150 µg
0.03 µg%
61. In which forms cortisol is transported through
blood?
• 75% is by binding protein called transcortin.
• 15% is by binding albumin.
• 10% is free form.
62. What is the advantage of steroid binding to specific
protein?
Inhibition or inactivation of steroid by liver is favoured.
63. What are the chief functions of glucocorticoids?
These are as follows:
• Counteracts the symptoms produced due to stress.
• Concerned with metabolic process of carbohydrate
and also protein, fat in an antagonistic manner to that
of insulin.
• Depression of function of lymphoid tissue, decrease
of eosinophil count, depressed tissue reactions.
64. What is the common synergistic and antagonistic
action between insulin and hydrocortisone?
• Synergistic—Augmentation of glycogenolytic action.
• Antagonistic—Lipotropic action and promotion of
glucose utilisation.
65. What do you mean by primary aldosteronism
(Conn’s syndrome)?
It is due to aldosterone oversecretion mainly due to
adenoma in adrenal cortex which ultimately results:
• Sodium retention and K+ depletion.
• Alkalosis—that causes muscular weakness and tetany.
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ENDOCRINAL SYSTEM 203
Hypertension and congestive heart failure without
edema.
Polyuria and polydypsia.
66. What is secondary aldosteronism?
When aldosterone secretion is increased not due to
adrenal cortical change but due to other factors like
severe hemorrhage, diarrhoea, dehydration, sweating,
nephrosis, congestive heart failure it is known as
secondary aldosteronism.
67. What is the glucose fever?
The patient with adrenal cortex insufficiency if suffers from
circulatory collapse, glucose infusion may cause high
fever known as glucose fever.
68. What do you mean by addisonian or adrenal crisis?
This is an acute form of adrenal cortex insufficiency which
occurs after removal of adrenal cortex or withdrawal of
therapeutically administered glucocorticoids or the
patients with reduced basal secretion of cortisol and
exposed to a sudden stress or infection.
69. In Cushing Syndrome why the pateint appears a
moon like face and buffalo like hump?
In Cushing syndrome there is increased secretion of
glucocorticoids which promote deposition of fat in unusual
sites on the body to result moon like face and buffalo
hump.
70. What is Conn’s syndrome?
Primary aldosteronism or Conn’s syndrome is the clinical
condition due to excess aldosterone secretion due to
tumor or hyperplasia of Z. Glomelulosa of adrenal cortex
which is characterised by:
(i) Muscular weakness (due to prolonged
hypokalemia)
(ii) Hypokalemic nephropathy
(iii) Increase in plasma Na+,
204 VIVA IN MEDICAL PHYSIOLOGY
(iv) Increase in plasma aldosterone level without
oedema due to aldosterone escape
(v) Increase in urinary aldosterone level
(vi) Decrease in plasma K+
(vii) Decrease in plasma renin
(viii) Albuninuria
71. What is General Adaptation Syndrome? What is it’s
role in combating stress?
The general manifestation of stress are called the general
adaptation syndrome which is contributed by sympathoadrenal medullary system in which adrenal medullary
hormones contribute to the Fight or Flight response by
following ways:
• Allows more light to enter into eyes by relaxing
acomodation and producing pupillary dilatation.
• Provides better perfusion of vital organs and muscles.
• Shortens the bleeding time (if wounded).
• Reinforcing the alert and arousal state by decreasing
the threshold in reticular formation.
• Increasing glycogenolysis in liver and lipolysis in
adipose tissue to increase energy supply.
72. What is general adaptive syndrome?
General manifestation of stress is called general adaptive
syndrome. It occurs in 3 stages:
• Stage of alarm—No adaptation takes place.
• Stage of resistance—Optimum adaptation occurs due
to the interaction of adrenal cortex and adrenal
medulla.
• Stage of exhaustion—Due to continued stress.
73. What is Addison’s disease?
It is a state of chronic adrenal insufficiency when the gland
is incapable of producing glucocorticoid hormones
particularly under stress. This results in severe shock,
low blood pressure, high K+ level in serum, dehydration
and pigmentation, muscular weakness, mental confusion,
etc.
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74. Describe the adrenogenital syndrome?
This is due to tumor of adrenal cortex which causes
excessive secretion of sex steroids therefore the male
children get precocious development of sex organs with
early onset of puberty, sex desire and secondary sex
characteristics.
Prepubertal and adult females develop male
secondary sex characters known as adrenal virilism. The
characteristic features include deepening of the voice,
amenorrhoea, enlargement of clitoris, masculine types
of muscle growth.
75. What is the cause of Cushing syndrome?
It is due to oversecretion of cortisol which is due to
bilateral adrenal hyperplasia or adrenal tumour.
76. What are the main signs and symptoms of Cushing
syndrome?
These are:
• Retardation of growth in childhood
• Moon like face.
• Hirsutism or increase in facial hair.
• Thin extremities, penduler abdomen and buffalo hump
due to centripetal distribution of fat.
• Muscular weakness, edema, polyuria, nocturia,
osteoporosis, etc.
77. What is the main secretory product of adrenal
medulla?
It is adrenaline.
78. What are the basic differences of norepinephrine
(NE) and epinephrine (EP) in relation to their
function?
NE is mainly secreted by sympathetic nerves and are
mainly responsible for regulation of vascular tone, blood
flow and BP whereas EP is mainly secreted by adrenal
medulla which has predominant action on metabolism.
206 VIVA IN MEDICAL PHYSIOLOGY
79. What are the main functions of adrenaline?
These are as follows:
• Increase in systolic BP, HR, force of contraction,
cardiac output and conductivity.
• Dilatation of coronary blood vessels.
• Relaxation of smooth muscles with constriction of
sphincters.
• Vasoconstriction with excessive sweating of skin.
• Dilatation of pupils.
• Relaxation of bronchial musculature.
• Calorigenic action on metabolism.
80. What is phaeochromocytoma? What are its
characteristic features?
It is chromaffin cell tumour (benign) of adrenal medulla
with oversecretion of noradrenaline and also epinephrine.
Characteristic features:
• Sustained systemic hypertension.
• Headache, sweating, severe palpitation, weakness,
anxiety, extreme cold sensation.
• Nervous manifestations like tremor, giddiness.
• Increased body temperature, hyperglycemia,
glycosuria and increased BMR.
81. What are the hormones that regulate blood glucose
level? Which one is the most important?
Insulin, glucagon, epinephrine, hydrocortisone, ACTH,
growth hormone and thyroxin, out of which insulin is most
important.
82. Name the cells of islets of Langerhans and their
secretory products.
α cells—Glucagon
β cells—Insulin
δ cells—Somatostatin (GHIH) and gastrin.
83. Name the hormones which are antagonistic to the
insulin?
GH, thyrotrophic hormone, ACTH and glucagon.
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84. What are the main functions of glucagon? Why it is
called as ‘hormone of energy release’?
Glucagon is glycogenolytic, gluconeogenic, lipolytic and
ketogenic hormone. Thus it favours the breakdown of
stored nutrients. This is why it is known as hormone of
energy release.
85. What is the average daily requirements of insulin?
It ranges from 30-50 units/day.
86. What do you mean by labile and stable pool of
insulin?
Labile pool are the total storage amount of insulin in
pancreas. Injection of glucose first initiates the release
of 2% of labile pool of insulin and this response is known
as primary response. Stable pool are the newly
synthesised insulin that is released during 2nd stage after
injection of carbohydrate.
87. Mention the main function of insulin.
It is glycogenic, antigluconeogenic, antilipolytic,
antiketotic. Thus it favours the storage of absorbed
nutrients and that is why it is known as hormone of energy
storage.
88. Name different varieties of insulin used for
therapeutic purpose.
Soluble insulin, globin zinc insulin, protamin zinc insulin,
etc.
89. Define hyperglycemia and glycosuria.
Increase in blood glucose level beyond normal range,
i.e. increase in fasting blood glucose level beyond 100
mg% is termed as hyperglycemia and when it exceeds
the renal threshold (>180 mg%) then glucose is excreted
through urine. This condition is called as glycosuria.
208 VIVA IN MEDICAL PHYSIOLOGY
90. What is the normal blood glucose level in fasting
condition?
It is 60-95 mg%.
91. Define hypoglycaemia. What are the effects of
hypoglycaemia?
Fall of blood sugar level below 40 mg% is termed as
hypoglycaemia.
The characteristic features are: Mental confusion,
giddiness, visual disturbances, syncope, coma,
convulsions.
92. Define diabetes mellitus.
It is a pathological condition characterised by
hyperglycaemia and also glycosuria in extreme cases
usually due to deficient insulin secretion or its inactivation.
93. Why in diabetic ketotic patient K+ should also be
administered along with insulin?
If diabetic ketotic patient is treated with insulin, it develops
severe hypokalaemia which may be fatal. To overcome
this severe hypokalaemia, K+ is also administered.
94. What are the predisposing factors of diabetes
mellitus (DM)?
These are: Heridity, age (more common in old age),
obesity.
95. What are the signs and symptoms of diabetes
mellitus?
These are: Hyperglycemia, glycosuria, polyuria,
dehydration, polydypsia, polyphagia.
96. What do you mean by ‘Starvation in the midst of
Plenty’?
In case of DM there is hyperglycemia. One of the
important causes of this is the decreased utilisation of
glucose by the cells. As a result there is intracellular
glucose deficiency inspite of plenty of extracellular
glucose. This situation is called as starvation in the midst
of plenty.
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97. What do you mean by hyperosmolar coma?
Diabetic coma resulted from renal failure, cerebral
ischemia and severe dehydration produces
hyperosmolarity by causing water to flow out of cells and
ultimately coma known as hyperosmolar coma.
98. What are the different types of DM?
Two types:
• Juvenile type:
– Usually severe
– Insulin dependent
– Occurs in children and young adults.
– Accompanied by loss of weight
• Adult type:
– Usually mild
– Occurs in middle-aged person
– Non-insulin dependent
– Person becomes obese.
99. What do you understand by glucose tolerance test
(GTT)?
It is a common clinical laboratory method to investigate
the cases of diabetes mellitus and certain other
conditions. The patient is kept on about 300 gm
carbohydrate diet daily for 3 days. Fasting sample is
collected in the morning after which the patient is
administered glucose by oral route (1 gm/kg of b.w). The
blood and urine samples are collected ½, 1, 1 ½ and 2
hours interval. The blood glucose values are estimated
and urine is tested for presence of glucose. The values
of glucose are plotted in a graph paper to obtain a
characteristic graph.
100. What are types of GTT graph curves?
Three types:
• Normal curve,
• Lag curve and
• Diabetic curve.
The lag curve is seen in early diabetic patients.
210 VIVA IN MEDICAL PHYSIOLOGY
101. Differentiate between
hypoglycemic coma?
hyperglycemic
and
Parameter
Hyperglycemic coma
Hypoglycemic coma
1.
Cause
Due to increase in blood
glucose level (>400 mg%)
Due to fall of blood glucose
level (< 40 mg%) and more
severe.
2.
Rate of onset
Slow
Rapid
3.
Signs and
symptoms
(i)
Breathing
Deep and rapid breathing
Laboured breathing called
air hunger or Kussmaul
breathing.
(ii)
Sweating
Absent
Usually marked.
(iii) Hydration
Marked dehydration
Normal
(iv) Urine exam.
Marked glycosuria
and ketonuria
Not specific.
102. What are the hormones secreted by thymus gland
and mention their function.
Two hormones:
• Thymosin—Secreted by reticuloendothelial tissue in
thymus and stimulates lymphopoiesis both within the
thymus and peripheral lymphoid tissue.
• Thymopoietin or thymin—Inhibits ACh release at motor
nerve endings in myasthenia gravis.
103. Where does pineal gland present?
It lies between the superior colliculi, i.e. roof of 3rd
ventricle at the posterior end of corpus callosum.
104. What are the analogous organ of pineal in relation
to its function?
Adrenal medulla, post-pituitary and JG cells. All of these
secrete hormone in direct response to nervous activity
like pineal gland which secretes hormone melatonin in
response to sympathetic nerve activity.
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105. What are the functions of pineal glands?
It is not certain in case of human but it is predicted that it
has got some role in:
• Regulation of onset of puberty—It secretes
gonadotrophin inhibiting peptide which may delay
onset of puberty, though its role in human is not
confirmed.
• Pigmentation of skin by secreting a hormone known
as melatonin in response to darkness.
106. What are local hormones? Give examples.
The hormones which act at the sites of their synthesis
and release are called as local hormones like ACh,
histamin, PG, angiotensin, plasma kinins, etc.
107. What is physiologic GUT factor? Why oral glucose
administration is more effective than intravenous
glucose administration?
Gastric inhibitory peptide (GIP) in very small concentration
can increase insulin secretion. That is why it is known as
physiologic gut factor. This is the reason also why oral
glucose administration is highly effective as glucose in
GIT can secrete GIP which can increase the insulin
secretion separately. On the other hand if glucose is
administered intravenously there is no question to its
presence in GIT, there by no GIP secretion, so no
additional insulin secretion.
108. What is APUD cells ?
GIT contains some cells which can take up amine
precursors and decarboxoylate them to convert it as
amines. Therefore these cells are known as Amino
precursor Uptake and Decarboxylation (APUD) cells.
Similar types of cell are also present in brain normally
and also in some cases of lung cancer. G cell is one type
of APUD cells.
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1.12
Reproductive System
1. What is the name of the premitive germ cells?
Female premitive germ cell—Oogonia
Male premitive germ cell—Spermatogonia.
2. Which chromosome determines the type of sex?
What is H-Y antigen?
Y sex chromosome determines the type of sex. The testis
determining gene product is known as H-Y antigen.
3. What do you mean by SRY chromosome?
The gene present in the tip of the short arm of the human
Y chromosome causes differentiation of indifferent or
bipotential gonad to embryonic testis in the 7th–8th weeks
after gestation. The region of the Y chromosome that
contains the testis determining gene is called as SRY
chromosome.
4. What is sex chromatin or Barr body?
Soon after cell division has started during embryonic
development one of the two X chromosomes of the
somatic cell in normal female becomes functionally
inactive. The inactive X chromosome is known as sexchromatin or Barr body.
5. What is the name of sex chromatin in male?
It is known as F body.
6. To identify sex genotype certain cells are used for
the cytological test. What are these cells?
These are: The epithelial cells of epidermal spinous layer,
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REPRODUCTIVE SYSTEM 213
buccal mucosa epithelial cells, vaginal epithelial cell,
leucocytes.
7. Name the abnormalities of sexual differentiation
due to non-disjunction of sex chromosome?
These are superfemale (44X XX), Klinefelter’s syndrome
(44XXY), Turner’s syndrome (44X0).
8. What are the phenotypic features of Klinefelter’s
syndrome?
Characteristic features:
• Genetic sex is female
• Chromosomal configuration 44XXY
• Atrophied testis (Gonadal sex)
• Phenotypic features:
• Male like appearance with feminine stigma
• Bilateral Gynaecomastia
• Sterile and impotent
• Low or normal plasma testosterone level
• High serum LH but normal FSH level
• Small penis, testis, seminal vesicles, etc.
• Secondary sex characters present
9. Name the abnormality of sexual differentiation due
to nondisjunction of autosome.
It is Down’s syndrome or mongolism.
10. What do you mean by male pseudohermaphroditism?
If the female internal genital organs develop in genital
male due to less secretion of androgen by defective testis,
it is known as pseudohermaphroditism.
11. What is spermiogenesis?
It is the sequence of developmental events by which
spermatids are transformed into mature sperm without
having any further division. The major features of this
transformation include:
• Formation of an acrosome
• Development of flagellum
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•
•
•
Condensation of the chromatid accompanied by
changes in the shape and size of the nucleus.
Loss of excess cytoplasm
Synthesis of numerous proteins unique to the
spermatozoa.
12. Name the phases of spermiogenesis.
These are: Golgi phase, Cap phase, Acrosomal phase
and Maturation phase.
13. Define puberty. What is the onset period of puberty
in male and female?
Puberty is the period when the endocrine and
gametogenic functions of the gonad have first developed
to the point where the reproduction is possible.
For female onset period is between 8-13 years, for
male it is 9-14 years of age.
14. What do you mean by Euspermia, Oligospermia and
Azoospermia?
• When sperm count is more than 20 millions/ml it is
known as euspermia.
• When sperm count is in between 5-20 million/ml it is
known as oligospermia.
• When the sperm count is < 5 millions/ml it is known as
azoospermia.
15. Before puberty the hypothalamus is more sensitive
to the inhibitory effects of gonadal steroids and
keeps the release of hypothalamic GnRH under
check. At puberty this sensitivity decreases which
is responsible for initiation of puberty—How?
The exact mechanism by which the sensitivity of
hypothalamus to this negative feedback effect of gonadal
steroid decreases is not known yet, but it is assumed
that before puberty pineal gland secretes melatonin which
inhibits hypothalamus to release GnRH. With the
advancement of age the pineal gland becomes calcified
thereby no melatonin secretion. This results withdrawal
of its inhibitory effect on hypothalamus. So the
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hypothalamus now starts secreting more GnRH to initiate
puberty.
16. What is adrenarch?
At the time of puberty there is an increase in secretion of
adrenal androgens without any change in the secretion
of cortisol or ACTH. The onset of this increased adrenal
secretion is called as adrenarch.
17. What do you mean by Eunuchoidism and primary
amenorrhoea?
In some individuals puberty is delayed even though the
gonads are present and other endocrine functions are
normal. This clinical condition in male is called as
eunuchoidism and in females it is known as primary
amenorrhoea.
18. What is precocious puberty?
Early development of secondary sexual characteristics
is called as precocious puberty.
19. Enumerate the function of FSH and LH in both male
and female.
• FSH on female: Responsible for early growth of ovarian
follicles.
• FSH on male: Maintains the spermatogenic epithelium.
• LH on female:
• Responsible for final maturation of ovarian follicles.
• Responsible for ovulation and initial formation of
corpus luteum.
• Responsible for progesterone secretion.
• LH on male: Stimulates Leydig cell to release
testosterone.
20. What is blood testis barrier? What is its function?
In between the Sertoli cells and other cells linning the
seminiferous tubular wall there are tight junctions which
prevent the free movement of substances acrosss it. This
is known as blood testis barrier. Its functions are:
216 VIVA IN MEDICAL PHYSIOLOGY
•
•
Helps in maintaining the composition of the fluid in
the lumen of seminiferous tubule.
It helps to prevent entry of sperm into blood and also
protects the sperm from blood-borne noxious agents.
21. Which is the primary store house of spermatozoa?
Where from it get’s energy during storage there?
It is in epididymis. Epididymal secretion contains high
concentration of glycerophosphoryl choline which is the
potential source of energy.
22. Where does spermatozoa first become mature?
In epididymis when they are exposed to O2.
23. Which one is secondary store house of spermatozoa? Even after vasectomy why contraceptive
methods are suggested to be used for 2-3 months?
Secondary store house is vas deferens. It is because
after vasectomy viable spermatozoa are stored in the
ampula for 2-3 months and thus may be released and
may cause fertilisation. To prevent it, contraceptive
methods are used for initial 2-3 months after vasectomy.
24. What is the importance of fructose present in
semen?
Spermatozoa have very little cytoplasm and therefore use
fructose as their metabolic fuel.
25. What is the maximum duration of fertilising capacity
of sperm?
It is 24-48 hours after the entry in female genital tract
though motility persists for 48-60 hours.
26. What do you mean by capacitation and acrosomal
reaction?
When the spermatozoa are first expelled in, they are
unable to perform fertilisation of the ovum due to the
presence of some inhibitory factors within the semen.
However, on coming contact with the fluids of female
gential tract multiple changes occur that ultimately
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activate the sperm for the fertilisation. These collective
changes are called as capacitation of the spermatozoa.
When the sperms come in contact with zona pellucida
of ovum there is a release of stored enzymes from
acrosome of the sperm like hyaluronidase and proteolytic
enzymes that facilitates the penetration of the sperm
through the zona pellucida. This reaction is known as
acrosomal reaction.
27. What is the source of testosterone?
It is:
• Mainly Leydig cells of testis.
• Partly by the zona reticularis layer of adrenal cortex.
28. What is inhibin?
In response to increased FSH secretion by pituitary gland
sertoli cells release one testicular factor which inhibits
further FSH secretion by negative feedback mechanism.
This testicular factor is known as inhibin.
29. What do you mean by cryptorchidism? What is its
effect on testis?
Incomplete descending of one or both testes in newborn,
i.e. testis remains in the abdominal cavity or inguinal canal
without descending to scrotum is called as cryptorchidism.
Due to the high temperature in abdominal cavity the sertoli
cells are degenerated thereby spermatogenesis fail to
occur resulting sterility.
30. What are the effects of castration before puberty?
These are as follows:
• Absence of characteristic changes at puberty.
• Secondary sex organs do not develop fully.
• General musculature remains poor.
• Voice remains boyish type.
• Individual remains sterile and impotent.
31. What are the effects of castration after puberty?
These are as follows:
• The individual becomes sterile but sex urge is retained.
218 VIVA IN MEDICAL PHYSIOLOGY
•
•
Seminal gland and prostates become atrophied.
There is general muscular asthenia.
32. Name the ovarian hormones with each of their
source and daily secretion.
Estrogens:
• Source: Theca interna cells of graffian follicles.
• Secretion: 35-300 µg in different stage of menstrual
cycle.
Progesterons:
• Source: Corpus luteum.
• Secretion: 0.9 ng /ml in follicular phase and increases
20 times in luteal phase.
Relaxin:
• Source: Corpus luteum.
33. What are the functions of relaxin?
It facilitates child birth by causing:
• Relaxation of the symphysis pubis and other pelvic
joints.
• Initiation of uterine contractility.
• Softening of the cervix.
34. What are the different phases of menstrual cycle
and what is its cause?
There are 4 phases:
• Menstrual phase: It is due to withdrawal of
progesterone secretion.
• Proliferative phase: It is due to estrogen secretion.
• Ovulatory phase: It is due to LH surge.
• Secretory or luteal phase: It is due to increase in
secretion of progesterone.
35. What is estrogen surge, FSH surge and LH surge?
• In the preovulatory phase of menstrual cycle rise of
FSH concentration increases the serum concentration
of estradiol to reach a peak at 12-13 days (in case of
28 days cycle), called oestrogen surge (Fig.
1.12.1A).
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Within 24 hours of oestrogen surge, the increased
level of oestrogen augments the responsiveness of
the pituitary to GnRH which induces a burst of LH
secretion. This peak rise of LH in serum is known as
LH surge (Fig. 1.12.1B).
At the same time when LH peak occurs serum
concentration of FSH also increases suddenly to a
peak level called FSH surge (Fig. 1.12.1C).
Figs 1.12.1A to C: Hormonal level during ovarian cycle
220 VIVA IN MEDICAL PHYSIOLOGY
36. What do you mean by withdrawal bleeding?
If no fertilisation takes place, corpus luteum regresses
by the process known as luteolysis resulting sharp fall of
estrogen and progesterone secretion. This inturn causes
spasm in spiral arteries and thereby ischemia of superficial
layer of endometrium. This ultimately leads the shedding
of superficial layer of endometrium and thereby release
of blood and mucous through vagina known as withdrawal
bleeding.
37. What is corpus luteum and corpus albican?
• After ovulation capillaries from the theca interna
rapidly invade dividing granulosa cells layer and the
clotted blood is replaced by yellowish, lipid rich luteal
cells known as corpus luteum.
• If fertilisation do not occur the corpus luteum regresses
and eventually forms corpus albicans.
38. What is the lifespan of corpus luteum? What is its
function?
If fertilisation does not occur it servives for upto 14 days
but if fertilisation occur then it survives upto 3-4 months.
Its function is to synthesise and release progesterone.
39. What do you mean by CL of Pregnancy and CL of
fertilisation?
If the ovum is not fertilized the corpus Luteum (CL)
persists for about 14 days which secretes progesterone
to initiate endometrial growth required for implantation of
zygote. These CL are small and known as corpus luteum
of menstruation. Whereas, if the ovum is fertilized and
pregnancy results CL persists for 3-4 months and
maintains the growth of endometrium. At this stage CL
size is longer and known as corpus luteum of
pregnancy. After 3-4 months it degenerates and it’s
function is taken over by the placenta.
40. What are the various natural forms of oestrogen?
These are oestradiol, oestrone and oestriol.
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41. What are the main synthetic forms of estrogen and
progesterone?
• Oestrogen—Diethylstilbestrol and hexosterol.
• Progesterone—Pregninolone.
42. What is ovulation? When does it occur?
Ovulation is the release of ovum from ovary at fairly fixed
interval of menstrual cycle.
Its appropriate timing is not fixed. In case of regular
cycle of 28 days it is generaly the 14th day when ovulation
takes place. However, if the cycle is irregular and it is say
24 days or 34 days then the ovulation will occurs at 10th
and 20th day of cycle respectively.
43. What is the physiological basis of BBT as indicator
of ovulation?
At the time of ovulation body temperature rises by 0.3 to
0.5°C than the temperature at preovulatory phase. This
increase in temperature is due to the increase of
progesterone level in blood which is thermogenic.
44. What is menopause? What is its cause?
Menopause is the period of life when menstruation
naturally stops permanently. This is due to the exhaustion
of the graffian follicles in the ovary which in turn produces
egg or ovum.
45. What are the signs and symptoms of menopause?
At the onset of menopause initially the menstrual cycle
becomes irregular and finally ceases altogether. There
is a fall in oestrogen level that causes atrophy of external
genitalia, uterus, breasts with decline in sexual urge.
Some other symptoms are hot flushes, profuse sweating,
transitory emotional disturbances, giddiness, etc.
46. What do you mean by safe period?
Just before ovulation, i.e. 2 days before ovulation (as
sperm can survive maximum of 2 days in female genital
tract) and 2 days after ovulation (as ovum released are
functionally active up to 24-48 hrs after ovulation) there
222 VIVA IN MEDICAL PHYSIOLOGY
is a minimum chance to conceive. That is why beyond
this period, menstrual cycle is safe in relation to
conception and is known as safe period though nowadays
it is believed that there is no real safe period specially in
irregular menstrual cycle.
47. Name the contraceptive measures in male.
These are as follows:
• Use of condom
• Coitus interruptus
• Vasectomy
• Use of spermatogenesis inhibiting drugs.
48.
Name the contraceptive measures in female.
These are as follows:
• Use of diaphragm
• Use of spermicidal jellies and cream
• Coitus during safe period
• Tubectomy
• Intrauterine device
• Use of contraceptive pills.
49. What are the disadvantages of contraceptive pills?
These are as follows:
• High risk of thrombo-embolic phenomenon
• Increase of systemic BP
• Precipitation of diabetes mellitus.
50. What is the physiological basis of pregnancy
diagnostic tests?
It is based on the presence of hCG in urine which can be
detected as early as 14 days after conception, i.e. 10-14
days after the 1st missed period.
51. What is the average duration of human pregnancy?
It is 280 days or 40 weeks when calculated from the 1st
day of last menstrual period.
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52. Name some pregnancy diagnostic tests besides
immunochemical tests?
These are Ascheim Zondek test, Friendman’s test,
Kupperman’s test, Hogben’s test, etc.
53. Explain Ascheim Zondek test?
54. In this test 2 ml urine of a subject is injected
subcutaneously in female non-pregnant mice for 3 days.
On the 5th day if there is hemorrhagic spot or corpora
lutea present in ovaries it is considered as positive for
pregnancy.
55. What do you mean by double Bohr’s effect?
In the feto-placental unit while flowing though the placenta
the PCO2 of fetal blood decreases due to pressure
gradient. This shifts O2 - Hb dissociation curve to left to
cause increase loading of O2 by the fetal blood.
Whereas PCO2 of maternal blood increases as it picks
up the CO 2 from fetal blood. This shifts O 2 –Hb
dissociation curve to right and causes increased of
unloading of O2. This event is known as double Bohr’s
effect.
56. What is amniotic fluid? What is its function?
Amniotic fluid is a clear fluid which is collected in the
amniotic cavity and surrounds the foetus.
Its functions are as follows:
• To provide the foetus with fluid to drink
• To keep the foetus at an even temperature
• To protect the foetus from injury
• To provide a medium for foetal movement.
57. What do you mean by lactogenesis and
galactopoiesis?
Initiation of milk secretion is known as lactogenesis
whereas maintenance of milk secretion is called as
galactopoiesis.
224 VIVA IN MEDICAL PHYSIOLOGY
58. What is Colostrum?
It is a deep yellow coloured protein and salt enriched
fluid secreted by the breast during first 3 days after childbirth.
59. Lactating mother does not generally become
pregnant—Why?
During lactation cyclic ovarian function ceases in lactating
mother due to the inhibition of hypothalamic GnRH release
by reflex initiated in response to suckling of nipple.
60. What is meant by transition and mature milk?
The milk secreted during the first few weeks after
parturition is known as transition milk. Whereas the milk
appears at the end of the 1st month is called as mature
milk.
61. Name the proteins in human milk.
It is caseinogen and lacto albumin.
62. What do you mean by ash in relation to milk?
It is the minerals present in milk which are Ca2+, K+, Na+
phosphorus and Cl– in traces.
63. What are the differences between human’s milk and
cow’s milk?
Human’s milk
1.
2.
Cow’s milk
It contains less protein, less
It contains more protein, more salts
salts and more carbohydrates and less carbohydrates.
Caseinogen is present more
Comparatively in less amount.
in amount.
3.
It contains less fatty acids.
It contains more fatty acids.
64. When does heart beat begins in foetus?
It begins by 4th week of pregnancy.
65. When does GIT develop in the foetus?
It starts to develop by 4th month and by 7th month it
grows almost upto normal stage.
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66. When do the kidney develops in the foetus?
These develop mostly by 3rd trimester of pregnancy but
normal functioning becomes complete only few months
before birth.
226 VIVA IN MEDICAL PHYSIOLOGY
SECTION II: PRACTICAL VIVA
Part A
Hematology
1. Which blood is generally used in hematological
practical–Capillary blood or Venous blood?
Capillary blood.
2. What is the difference between capillary blood and
venous blood?
Capillary blood is obtained from punctured capillaries,
smallest arterioles or venules by a skin puncture usually
over a finger or ear lobe or the heel of the foot (in infants)
and shows lower cell counts, lower hemoglobin
concentration and PCV values as some tissue fluid always
dilute the blood, whereas the venous blood is obtained
from a superficial vein by venopuncture which shows
comparatively higher cell counts, higher Hb percentage
and PCV values as it is not contaminated with tissue fluid.
3. Why the capillary blood is called peripheral blood?
Capillary blood is called as peripheral blood as it comes
from the peripheral blood vessels like venules or smallest
arterioles or capillaries in contrast to venous blood.
4. Why the thumb or little finger is not pricked for
collecting blood?
It is because the underlying palmer fascia from these
digits extends up to the forearm. So in case of any
infection at the site of injury, there is a chance of the
infection to spread up to the forearm.
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5. In case of infants where from you will collect the
capillary blood?
It is from either big toe or heel as the fingers are too
small.
6. What measures will you take to prevent the
spreading of hepatitis infection following pricking
of finger?
The needle used to prick the finger should be heated
over flame.
7. Why should the pricked finger not to be squeezed?
Squeezing the finger results coming out the tissue fluid
that dilutes the capillary blood and thus giving lower
values.
8. What are the features of ideal blood film?
These are:
i. It should be tongue shaped, uniformly thick, neither
too thick nor too thin and should occupy the middle
2/3rd of the slide.
ii. Microscopically all the cells should be separate
without any overcrowding and rouleaux formation.
9. What is the composition of Leishman stain? What
are the function of each constituent and why the
stain should be acetone free?
The composition and function of each constituents is:
A. Leishman powder: 0.15 gm
i. Eosin: An acidic dye stains basic part of cell e.g.;
cytoplasm
ii. Methylene blue: A basic dye stains acid part of cell
e.g. nucleus
B. Methyl alcohol (Acetone free): 100 ml (as a fixative
and solvent)
Acetone free methyl alcohol is used because the
acetone being a strong lipid solvent can even destroys
the cell by lysing the cell membrane.
228 VIVA IN MEDICAL PHYSIOLOGY
10. Why buffer solution is used instead of distilled
water in Leishman’s staining?
The pH of buffer solution is adjusted at 6.8 and at this
particular pH the ionization of stain is optimum, so the
stain particles can easily penetrate the cell to stain it.
11. Why is Leishman’s stain diluted after 1-2 mins?
During the initial 1-2 mins staining does not take place,
as the stain particles cannot enter the cell as long as
they are not ionized by addition of water. During this
period the absolute alcohol of Leishman’s stain serves
two functions:
• Fixes the blood cells on the glass by precipitating the
plasma proteins, which act as glue.
• Preserves the normal shape and chemistry of cells.
12. Can tap water be used for diluting the stain after
fixation?
It should not be used as methylene blue of Leishman’s
stain may be unable to stain the cells because of improper
pH.
13. Name any other stain that can be used to stain the
blood film.
Geimsa’s stain.
14. What do you mean by ‘Vital Staining’?
It is the special staining method to stain the living cells.
15. Why is cedar wood oil required to use Oil immersion
lens?
It is because the refractive index of this oil is similar to
that of glass avoiding the refraction of the light. Otherwise
the image will be faint and blurred.
16. Which part of the blood film should be avoided for
counting the cells?
“Head’ and extreme “Tail” part of the slide as the cells
present in these area are few in number and also
distorted.
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17. How do you differentiate between RBC pipette and
WBC pipette?
Parameter
RBC pipette
WBC pipette
Upper gradation
101
11
Diameter of bulb
More
Less
Colour of mouthpiece
Red
White
Colour of bead in the bulb
Red
White
18. What are the functions of the bulb in a diluting
pipette?
It helps the blood to be diluted and also to be mixed with
the diluting fluid.
19. What are the functions of the bead present inside
the bulb of the diluting pipette?
It:
1. Helps to mix the blood with the diluting fluid.
2. Helps to identify the pipette by just glancing it.
3. Gives an idea whether the pipette is wet or dry. If it is
dry the bead rolls freely inside the bulb.
20. Why it is important to discard the first two drops of
diluted blood from the pipette before charging the
counting chamber?
The stem of the pipette contains only the cell free diluent
which is to be discarded before charging the chamber;
otherwise the count will be low and thus erroneous.
21. Why any small excess of blood drawn into the
pipette should not be removed by a piece of
cotton?
If the cotton is used to remove the excess blood drawn in
the pipette then it will absorb only the fluid not the cells.
This will result in higher RBC/WBC count than the actual
value.
230 VIVA IN MEDICAL PHYSIOLOGY
22. How will you clean the pipette in case of clotting of
the blood inside the stem of the pipette?
It is to be kept in strong nitric acid or alkali or H2O2 for 24
hrs and then washed in the running tap water. A flexible
suitably thick metal wire is now inserted to clean the
capillary bore, finally rinse with alcohol or ether to dry it.
23. How will you clean the pipette?
It is by sucking up and blowing out distilled water several
times followed by sucking up and blowing out acetone
for drying it.
24. How will you clean the chamber and cover slip?
It is by washing it first with soap and water and then with
alcohol.
25. Can these pipettes be used for any other purpose?
The RBC pipette can be used for counting platelets,
WBCs (when their count is very high as in leukaemia)
and also for counting the spermatozoa in the semen.
26. What are the dimensions of WBC and RBC squares?
• Each smallest square for RBC counting:
(i) Area: 1/20 mm × 1/20 mm = 1/400 mm2
(ii) Volume: 1/400 mm2 × 1/10 = 1/4000 mm3
• Each smallest square for WBC counting:
(i) Area: 1/4 mm × 1/4 mm =1/16 mm2
(ii) Volume: 1/16 mm2 × 1/10 mm = 1/160 mm3
27. What are the features of an ideally charged
chamber?
These are:
• No flowing of blood into the trenches
• No air bubbles
28. When blood is taken to the mark 0.5 and the diluting
fluid to mark 101, why is the dilution 1 in 200 and
not 1 in 202?
The dilution of the blood occurs not in its stem but in the
bulb of the pipette, the volume of which is 101-1 =100.
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Hence half volume in hundred gives a dilution of 1 in
200.
29. If Haem’s fluid is not available can you use any
other?
0.9 gm% normal saline can be used but the cells have to
be counted within an hour after filling the pipette, even
though the red cells likely to form rouleaux.
30. How do you differentiate red cells from dust
particles?
The red cells are appeared in round discs of uniform
size and light pink in colour whereas the dust particles
are angular with varying size and colours.
31. What is the composition of Turk’s fluid? What is
the function of each constituents?
The composition and function of each constituents is;
a. Glacial acetic acid : 1.5 ml (hemolyses the red cells)
b. Gentian violet: 1.5 ml (stains the nuclei of WBCs)
c. Distilled water: up to 100 ml (as a solvent).
32. Name any other accurate method to do RBC count?
Use of electronic cell counter.
33. Why is it necessary to follow the rules of counting?
It is to avoid the error of missing some cells and counting
other more than once.
34. What is the fate of leucocytes in this experiment?
The leucocytes in this experiment are as much diluted
that its number are considered very negligible to consider
because:
• The low count of WBC in comparison to RBC.
• Dilution of the WBC by 100 times.
Occasionally leucocyte may be seen but its
concentration is very less (1 WBC for every 600-700
RBCs, i.e. one WBC in 80 squares). So even if it is
counted along with the RBCs the RBC count will not vary
too much (i.e. 10,000/cmm of blood).
232 VIVA IN MEDICAL PHYSIOLOGY
35. What do you mean by the term ‘Glacial’? Why it
should be glacial acetic acid in Turx's fluid?
Glacial means pure. Only the pure form of acetic acid
can give the refractivity around the WBCs that helps the
WBC to be differentiated from the dust particles (which
are opaque).
36. What is the fate of the RBCs in this experiment
(Total count of leukocytes)?
RBCs are hemolysed by the glacial acetic acid otherwise
it would not be possible to count the WBCs.
37. Can any other agent be used to hemolyse the
RBCs?
No, any strong agent will also lyse the WBCs and any
weak agent will take long time to lyse them completely.
38. What is the difference between DLC and absolute
leucocyte count?
In DLC the percentages of different leucocytes are
determined whereas in absolute count the actual number
of different leucocytes per cu mm of blood are calculated.
39. How does the DLC of a child differ from that of
adult?
In adults the granulocytes (mostly neutrophil) predominate
whereas in children the lymphocytes predominate.
40. Can you get rough idea of TLC by doing DLC?
Yes, if the cells appear more frequently amongst the
RBCs the TLC will be high and vice versa.
41. Enumerate the sources of error in hemocytometry?
These are:
1. Pipette error, i.e inaccuracy in calibration and in
measurement.
2. Field error, i.e unequal distribution of cells over the
counting chamber due to:
a. Over-charging or under-charging of the chamber.
b. Presence of grease or oil on slides or cover slip.
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3. Personal error, i.e. wrong counting of cells.
4. Stastical error: It is inversely proportional to the
square root of the number counted.
42. Can you use oxalate mixture in Westergren method
and citrate solution in Wintrobe’s method?
No, the anticoagulants used for each method can not be
interchanged as both the methods are standardized with
the specific anticoagulant.
43. What are the advantages and disadvantages of
Wintrobe’s and Westergren method?
Wintrobe’s method:
a. Advantage: Same sample of oxalated blood can be
used for ESR first and then after one hour for PCV by
centrifuging it.
b. Disadvantage: The method is less sensitive as the
column of blood is not high.
Westergren method:
a. Advantage: The method is more sensitive as the
column of blood is high.
b. Disadvantage: Citrate solution used in this case dilutes
the red cells and thus tends to raise the ESR, however
as the fibrinogens and globulins of plasma are also
diluted there is also tendency of lowering the ESR.
44. Why ESR reading taken after one hour?
This is because more than 95-98 % of RBCs settle down
by the end of this time and after that the rate of
sedimentation of RBCs do not affect the ESR significantly.
45. Why the normal values of ESR are more in
Wintrobe’s method than that of Westergren
method?
It is because of:
• Effect of atmospheric pressure over the blood column
as the tube is kept open in it’s top.
• Nature of powdered mixture of oxalate solution used
as an anticoagulant.
234 VIVA IN MEDICAL PHYSIOLOGY
46. What is the importance of determining hematocrit?
It is simple but more accurate test for determining the
presence of anemia or polycythemia. It is also used for
determining various absolute corpuscular values.
47. Which cells make up the buffy layer? How thick it
is? When it’s thickness increases?
The buffy layer consists of packed leucocytes and
platelets. It is 1 mm thick. It’s thickness increases in severe
leucocytosis, leukaemia and thrombocytosis.
48. What is the difference between PCV of arterial
blood and venous blood? What is the reason
behind this difference?
The PCV of venous blood is higher than that of arterial
blood. It is because in the venous blood the RBCs gain
an extra weight due to the entry of water within it resulted
due to chloride shift.
49. Why colour index is not an appropriate index of
hemoglobin content of RBC?
It is because of wide range of normal value of RBC.
50. Which absolute corpuscular value is most useful?
It is MCHC because:
• It expresses the actual Hb concentration in RBCs only,
not in whole blood.
• It does not consider the RBC count for it’s calculation.
51. Is it possible to know the sex of a person from the
blood film?
Yes, in the blood film of females of the Barr body, i.e
chromatin of the sex chromosome is seen in some
neutrophils.
52. What are the features of a senile neutrophil?
These are less motile and least effective. These cells
commonly break up during the spreading of the blood
film.
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53. Which stage of Neutophil is most effective?
3-lobed neutrophil is the most motile and functionally most
effective in killing the bacteria.
54. Why Cook –Arneth count is not used as a routine
investigating tool?
This is because:
a. During some physiological conditions neutrophils used
to enter the circulation from various storage pools,
whereas during some other conditions there is shifting
of neutrophils to the storage pools, resulting shift to
the left or right. This normal phenomenon may give
the false indication about the status of bone marrow if
we totally depend on this investigating tool.
b. Besides this the better method like bone marrow
biopsy are now available for assessing bone marrow
function.
55. What are the indications of doing reticulocytes
count?
It is to assess the red cell forming and releasing activity
of the bone marrow.
56. How does a reticulocyte differs from the RBC?
The reticulocytes are comparatively larger than RBCs
and also contain dots, strands and filaments of bluish
stained material.
57. Why does the ABO incompatibility rarely produce
hemolytic disease on the newborn?
This is because the anti-A and Anti-B antibodies are IgM
type of immunoglobins that do not cross the placenta
because of their large MW and thus there is no chance
of antigen antibody reaction.
58. What do you mean by Zone phenomenon?
For agglutination to occur the concentration of antigen
and antibody has to be same, otherwise there will no
antigen antibody reaction. This is termed as Zone
phenomenon.
236 VIVA IN MEDICAL PHYSIOLOGY
59. What are the earliest effects of a mismatched
transfusion?
These are: Severe pain anywhere in the body, sense of
suffocation, feeling of tightness in chest, shivering and
even fever.
60. Which blood substitutes may be used to restore
blood volume if suitable donor is not available?
Crystalloid solution (glucose saline) and colloid solutions
like human albumin, dextrose with NaCl, etc.
61. Why does calcium deficiency not cause a bleeding
disorder though it is essential in blood coagulation?
It is because the calcium required for the blood clotting is
in minute quantities.
62. What is athrombocytopenic purpura and
thromboasthenic purpura?
Purpura with normal platelet count is called as
athrombocytopenic purpura and purpura with normal
count but abnormal circulating platelets is called as
thromboasthenic purpura.
63. What do you mean by fragility and hemolysis?
Fragility means the susceptibility of red cells to being
broken down by osmotic or mechanical stresses.
Whereas the hemolysis means the breaking down of red
cells resulting release of hemoglobin into the surrounding
fluid.
64. What is the effect of 5% glucose, 10% glucose, urine
and urea solution of any strength on red cells?
• 5% glucose: It is isotonic with blood, so no change in
size and shape of RBC.
• 10% glucose: It is hypertonic, so there is shrinkage
of red cells due to exo-osmosis.
• Urine: Urine is hypotonic so the red cells will swell up
due to entry of some water.
• Urea solution: Hemolysis of red cells due to entry of
urea followed by water into the red cells.
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65. Can strong acids or alkalis be used instead of HCl
to measure haemoglobin?
No. the strong acids will oxidize the hemoglobins and the
strong alkalis will cause disruption of Hb. So in both the
cases there will no formation of acid hematin.
66. What happens if more or less amount of N/10 HCl is
taken instead of required amount?
If less amount of acid is taken all the hemoglobin will not
be converted to acid hematin resulting a low value.
Besides this there may be clot formation due to improper
mixing of blood with acid. On the other hand if more than
the required amount of acid is taken the final colour
developed in case of severe anemia would be much
lighter than the standard.
67. Why it is necessary to convert hemoglobin in acid
hematin?
If hemoglobin is not converted into acid hematin then the
colour of oxy-hemoglobin, which has a wide spectrum of
colours, cannot be standarized.
68. Can tap water be used for diluting and colour
matching?
No, as the salt present in the tap water may cause turbidity
which will interfere with colour matching.
69. Can N/10 HCl be used for diluting and colour
matching?
Yes.
70. While matching the colour why it is important to lift
the stirrer above the solution but not take it out?
If the stirrer is kept in the solution it will lighten the colour
and thus matching will occur earlier resulting low value.
On the other hand if it is taken out every time during the
colour matching, some solution will go out of the tube
and thus again giving a low value.
238 VIVA IN MEDICAL PHYSIOLOGY
71. Classify the severity of anemia as per the Hb
concentration?
Depending on the Hb level the anemia may be graded
as:
• Mild
: Hb 10-2 gm%
• Moderate
: Hb 5-8 gm%
• Severe
: Hb below 5 gm%
Part B
Human Experiments
1. What are the general procedures of clinical
examination?
These are: Inspection, Percussion, Palpation and
Auscultation.
2. What is the normal shape of the chest?
It is elliptical.
3. What is the pulse respiration ratio?
It is 1: 4.
4. What type of respiratory movement is seen in
childhood, male and females?
• In male: Abdominal
• In female: Thoracic
• In children: Abdominal.
5. Why a person cannot commit a suicide by holding
his/her breath?
It is because of the breaking point, i.e. the point when a
breath has to be taken automatically due to the strong
ventilatory drive even if that person looses
consciousness.
6. What is the normal range of breath holding time
(BHT)? What are the factors affecting BHT?
Normal BHT is 40 sec to 1 min, however the world record
of BHT is 5 min 13 sec.
• The factors that increase the BHT are: Yoga training,
240 VIVA IN MEDICAL PHYSIOLOGY
•
motivation and breathing pure O 2 before holding
breaths, etc.
The factors decreasing the BHT are: Diseases like
chronic bronchitis, emphysema, etc.
7. What do you mean by breath holding attacks?
In some infants and young children (below 3 years) there
are sudden and brief breath holding attacks in which the
child starts crying, and becomes stiff and blue, and also
looses consciousness. There may be even convulsions.
This type of attack is generally precipitated by emotional
distress, e.g.; pain, anxiety, fright, frustration, etc.
8. Name the precautions that must be observed
during spirometric recordings?
These are:
• The subject should be well awared about the procedure
that he/she has to do.
• There should be no leakage of air anywhere from the
mouthpiece to the gas bell.
• The indicator must be brought to zero reading before
each determination.
9. Name the types of breathing. Where is it seen?
It is of 3 types.
• Thoracic: It is generally seen in adult female.
• Abdominal: It is generally seen in adult males and
children.
• Thoracoabdominal: It is generally seen in pregnant
women and also in all peoples after exercise.
10. What do you mean by 'Vocal fremitus'? What is its
importance?
The detection of vibrations transmitted to the hands
(placed over chest) from the larynx through bronchi, lungs
and chest wall during the act of phonation is called as
vocal fremitus.
Vocal fremitus gives the idea about the presence of any
blockade, fluid or air in the respiratory passage and also
SECTION II: PRACTICAL VIVA
HUMAN EXPERIMENTS 241
in pleural cavity. Thus it gives the idea about the status
of respiratory system. It is decreased due to any blockade
in respiratory passage or dampened by fluid or air in the
pleural cavity. It is increased due to consolidation of lungs
during pneumonia, etc.
11. Name the types of breathing sound with
explanation.
• Vesicular sound: These are produced by passage of
air in and out of alveoli in the normal lung tissue. These
are heard both during inspiration and expiration without
having any pause in between. However, the sound
during inspiration is intense and rustling in character
and of low pitch and its duration is alomost twice of
expiratory sound’s duration.
• Bronchial sound: These are produced by the passage
of air through the trachea and large bronchi. These
are also heard during both inspiration and expiration
without any silent gap. In this case, the inspiratory
sound is harsh and expiratory sound is more intense
and of higher pitch.
12. What do you mean by vesicular breath sounds,
Bronchial breath sounds and Tracheal breath
sounds?
By placing the stethoscope over the surface of chest, we
can listen some breathing sounds which are basically
two types: vesicular and Bronchial breath sounds.
• The vesicular breath sounds are produced by the
passage of air in and out of alveoli in the normal lung
tissue. The features of this type of sounds are:
 Are heard all over the healthy chest surface but
most typically over axillary and infrascapular
regions.
 Are heard both during inspiration and expiration.
 Inspiratory sound is of low pitch, intense and
rustling in character.
 There is no clear cut pause between inspiration
and beginning of expiration.
242 VIVA IN MEDICAL PHYSIOLOGY

•
•
The duration of inspiratory sound is at least twice
of expiratory sound.
The bronchial breath sounds are produced by the
passage of air through the trachea and large bronchi.
The features of this type of sounds are:
 Are heard normally over the trachea.
 Are heard both during inspiration and expiration
and are clear, blowing or hollow in character.
 The inspiratory and expiratory sounds have the
same character though the inspiratory sound is
harsh and becomes inaudible just before the end
of inspiration.
 Expiratory sound is of high pitch, more harsh and
audible throughout the expiration.
 There is silent gap between end of inspiration and
beginning of expiration.
The bronchial breath sounds that heard over the
trachea is known as Tracheal breath sounds,
though the tracheal sounds are much harsher and
louder.
13. What is Peurile breathing?
In children (and also during exercise) the breath sounds
are normally harsher which is termed as peurile breathing.
14. Why the cuff should be placed at the level of the
heart while the BP reading is being taken?
The pressure in any vessel below heart level is increased
and that in any vessel above the heart level is decreased
by the effect of gravity.
15. Name the sound on which basis the BP is measured.
It is Korotkoff’s sound.
16. Is Korotkoff sound produced in normal vessel?
Justify your answer.
No, as the blood flow in the vessels are laminar type.
When the blood flow through it is converted into turbulent
type then only this sound is produced.
SECTION II: PRACTICAL VIVA
HUMAN EXPERIMENTS 243
17. Which phase of Korotkoff’s sound indicates
diastolic pressure? Which one is true diastolic
pressure?
The last stage or the disappearance of the sound for the
1st time is considered as diastolic pressure. True diastolic
pressure is in between the muffling phase of sound and
disappearance of sound and close to disappearance of
sound for the 1st time, i.e. 2-4 mm Hg higher than the
phase where sound 1st disappears.
18. What do you know by auscultatory gap?
In some hypertensive patients, there is a silent gap in
between the series of Korotkoff sounds. As the mercury
column is lowered, a few faint sounds are heard which
soon disappear and again reappear at a much lower
pressure head. This brief interruption in the sounds is
called as auscultatory gap.
19. Why palpatory method is to be adopted before doing
auscultatory method?
It is for two purposes as follows:
• In case of hypertensive patient, there may be
auscultatory gap. In this situation, if the mercury
column is raised to this gap phases only, one may
miss the 1st appearance of sounds which indicates
the actual systolic pressure and thus a false low
systolic pressure is being recorded. To avoid this
palpatory method should be adopted before
auscultatory method.
• Without having any gross idea of systolic pressure of
a person if auscultatory method is adopted then the
pressure around the cuff has to be increased in a
greater extent (say 150-200 mm Hg) but the person’s
real systolic pressure may be much lower (Say 120
mm Hg). In this situation, this extra increase of
pressure may cause stress to that subject and thereby
false systolic pressure might be recorded.
244 VIVA IN MEDICAL PHYSIOLOGY
20. What is pulse? How can you record it?
It is a wave transmitted along the arteries during each
heart beat generated by the pressure differences during
cardiac cycle. It can be recorded by Dudgeon’s
sphygmograph.
21. How does the blood pressure recorded in the
femoral artery differs from that in brachial artery?
In the normal person (standing posture) the femoral
arterial pressure is more than the brachial arterial
pressure. This is because that the pressure recorded
from brachial or subclavian artery represents the side or
lateral pressure as those arteries originate as the side
arms from the wall of aorta, whereas the pressure
recorded from femoral artery represents the end pressure
as the femoral arteries are the direct extensions of the
aorta.
22. Why is it important to record the heart rate (pulse
rate) while studying the effect of exercise on blood
pressure?
It is because the effect of exercise on blood pressure
varies with the intensity of exercise and heart rate gives
us indications about the intensity of exercise.
23. What are the effects of muscular exercise on blood
pressure?
The effects of muscular exercise on blood pressure
depend on whether the muscle contractions are primarily
isometric or isotonic.
a. In isometric exercise:
• The heart rate rises largely due to decreased
vagal tone and also due to sympathetic stimulation
by psychic stimuli.
• Rise of both the systolic and diastolic pressure.
• Reduction of blood flow through the contracting
muscles due to compression of blood vessels.
SECTION II: PRACTICAL VIVA
HUMAN EXPERIMENTS 245
b. In isotonic exercise:
• Quick rise in heart rate and stroke volume due to
generalized sympathetic stimulation.
• Increase in cardiac output and systolic pressure.
• Net fall in total peripheral resistance.
• Diastolic pressure may remain same or may fall
or even increase a little.
24. Name some other cardiac efficiency test?
It is Treadmill test (TMT).
25. What do you mean by cardiac pulsation and apex
beat?
Any pulsation in the precordium which is normally due to
the forward systolic thrust of the apex of the left ventricle
is called as cardiac impulse or cardiac pulsation. Whereas
the apex beat is the lowest and outermost point of definite
cardiac pulsation which is usually located in the 5th
intercostal space 8-10 cm (about 3.5-4 inches) from the
mid-sternal line.
26. Is the apex beat visible always in normal person?
No, the apex beat may not be always visible in some
normal persons because:
• It may be located behind the rib.
• Thick chest wall due to fat or muscle.
• The breast may be pendulous
• The emphysematous lung may cover part of the heart.
27. Palpate the apex beat. What is the significance of
palpating apex beat?
Apex beat is palpated by placing the flat part of the hand
over the heart keeping the base of the palm over the
base of the heart and the fingers pointing towards the
apex. Once the cardiac pulsation is felt the ulnar border
of the hand and then the tip of the index finger is used to
locate and confirm the point of the apex beat.
Significance of the apex beat: The change of the normal
position, the force and the nature of the apex beat can
give the idea about the status of the heart, e.g.:
246 VIVA IN MEDICAL PHYSIOLOGY
•
•
•
•
Enlargement of the heart due to hypertrophy or
dilatation may shift of the normal position of the apex
beat.
Pulling and pushing of the mediastinum due to lung
disease may shift the position of the apex beat.
Diffuse, sustained and more forceful thrust indicates
left ventricular hypertrophy or hyperkinetic circulation.
A ‘tapping’ or ‘slapping’ apex beat may be seen in
mitral stenosis.
28. Which kidney is not generally palpable?
It is left kidney.
29. When are the deep reflexes exaggerated?
Deep reflexes are exaggerated during:
i. Upper motor neuron lesions above the anterior horn
cells.
ii. Nervousness and anxiety.
iii. Hyper excitability of the nervous system as in hyperthyroidism and tetanus.
30. What is reinforcement of reflexes and when it is
required?
Occasionally the elicitation of deep reflexes like knee jerk
is very difficult. In this situation reinforcement is employed
by asking the subject to perform some strong muscular
efforts like clenching the teeth, etc. while the examiner
strikes the patellar tendon. In this situation, reflex is
elicited and evident.
31. What is steriognosis? What is the center of it?
Ability to recognize a known object by handling with closed
eyes is known as steriognosis. The center of steriognosis
is sensory association areas of cerebral cortex.
32. What is the most remarkable feature of cerebellar
lesions? Clinically can you diagnose the cerebellar
lesion?
Intention tremor is the most remarkable feature. The
cerebellar lesion can be diagnosed by the tests are:
SECTION II: PRACTICAL VIVA
HUMAN EXPERIMENTS 247
finger nose test, rebound phenomenon test,
adiadochokinesis, Heel-knee test.
33. What is Rhomberg’s sign? For what test it is
adopted?
If a subject is asked to stand with the feet as close
together as possible and then asked to close his eyes, in
this situation he starts to sway from side to side as soon
as he closes his eyes. This test is known as Rhomberg
sign positive. It is tested to determine the loss of position
sense or sensory ataxia where it is positive. In case of
cerebellar ataxia, the patient is unsteady on his feet
irrespective of whether the eyes are open or closed.
34. What is Echoencephalograph?
It is an instrument used to detect midline displacement
caused by space occupying intracranial lesions.
35. Name the reflexes which are of mainly clinical
importance.
Tendon reflex and pupillary light reflex.
36. What is positive Babinski’s sign?
If plantar side of foot is scratched it normally causes
dorsiflexion of toes. In lesion of pyramidal tract, the
response is extension along with fanning of toes. This is
termed as Positive Babinski’s sign which is also normally
seen in infants.
37. Name the condition in which the earliest sensory
loss is the loss of pain and temperature?
Tabes dorsalis.
38. What happens to the muscle tone and tendon
reflexes in lower motor neuron paralysis?
Muscle tone becomes hypotonic and tendon reflexes
become absent.
248 VIVA IN MEDICAL PHYSIOLOGY
39. Which muscle is tested by asking the subject to
wrinkle the skin on his forehead?
It is oblicularis occuli.
40. Why irritants should not be used while testing for
smell sensation?
It is because the irritants may produce abnormal
stimulation of receptors in the respiratory tract resulting
coughing.
41. Define visual field.
The area visualized by each of the eye on the screen
when the gaze is fixed at an object is called as visual
field.
42. What do you mean by binocular vision? What is its
importance?
The central parts of the visual fields of two eyes coincide,
therefore anything in this position of the field is seen with
both the eyes called binocular vision. It plays an important
role in appreciation of perception of depth and proportion
of objects.
43. How do you distinguish between a convex and
concave lens without touching them?
Keep the lens close to the page of a book and the image
of the writing of the book is to be seen through it. If the
letters appear enlarged it is a convex lens and if letters
appear diminished in size it is a concave lens.
44. Which part of the retina are not tested by
perimetry?
It is the macular region, which contains the fovea centralis,
which is the region of most acute vision.
45. Name any other method of determining the field of
vision?
It is Confrontation test, which is a rough test to compare
a person’s visual fields with the examiner’s own.
SECTION II: PRACTICAL VIVA
HUMAN EXPERIMENTS 249
46. What is the intensity of the sound of ordinary
conversation?
It is 50-60 db at 6-8 feet.
47. At which intensity of sound there may be cochlear
damage?
It is more than 1014 times which is equal to 140 db
approximately.
48. What does a vision 6/60 mean?
It means subject’s visual acuity is normal, i.e. he /she
can be able to read the top letter from the distance of 6
meter.
49. How a decreased visual acuity can be corrected?
The decrease in visual acuity can be corrected by using
proper lens, e.g.: The myopic vision can be corrected by
using concave lens and the hypermetric vision can be
corrected by using convex lens.
50. Name the different types of refractive errors.
• Physiological:
– Spherical aberration
– Chromatic aberration
– Diffraction
• Pathological:
– Myopia
– Hypermetropia
– Astigmatism
51. Is there any role of rods in colour vision?
No, there is no role of rods in colour vision.
52. Whichone of the three tests is commonly used for
testing colour blindness?
It is Ishihara’s chart.
53. For what kind of jobs the proper perception of
colours is essential?
• Drivers of air, sea, road transport vehicles
250 VIVA IN MEDICAL PHYSIOLOGY
•
•
Workers in textile industries
Workers in painting industries.
54. What is the difference between colour anomaly and
colour anopia?
Anomaly refers to the colour weakness and anopia refers
to the colour blindness.
55. Name the unit of sound. Define bel.
Decibel is the unit of sound. Bel is the logarithm of the
ratio of the power of the sound to the intensity of the
reference sound, i.e.
Bel = log x Intensity of a given sound/Intensity of a
reference (Standard) sound.
56. What are the different tests for hearing?
Rinne's test, Weber' test, Schwabach test.
57. What do you mean by Rinne’s test positive?
Air conduction if is more than bone conduction it is known
as Rinne’s test positive which is considered as normal
ear function.
58. Why the sound is heard louder in a ear with
conduction deafness, when Weber’s test is
performed?
It is because of absence of masking effect of noise in the
diseased ear.
59. What do you mean by infrasonic, ultrasonic and
supersonic sounds?
The infrasonic refers to the frequencies of sound below
20 Hz. Ultrasonic refers to the sound frequencies above
20,000 Hz which can not be perceived by the human
beings. Whereas the term supersonic refers to the object
that can travel at a speed faster than that of sound.
60. Which frequency of sound is most sensitive to
human ear?
It is 1000-3000 Hz.
SECTION II: PRACTICAL VIVA
HUMAN EXPERIMENTS 251
61. What are the limitations of tuning fork tests of
hearing?
• It cannot give quantitative estimation of acuity of
hearing.
• While testing of bone conduction in one ear is done
the subject will also listen the sound in the other ear
as the bone conducted vibrations reach all parts of
the skull irrespective of site of the head where the
tuning fork is placed. This creates confusion to the
subject regarding the involvement of one ear or both
the ears.
62. What is audiometry?
It is the only reliable method to define the nature and
degree of hearing loss if any in a patient in which selected
pure tones of 125-8000 Hz can be fed into each ear
separately and the subjects electrical response is
recorded.
SECTION III: APPENDIX
IMPORTANT VALUES TO
REMEMBER
I. Blood
1. Hemoglobin
• At birth: 22-24 gm% (Avg-22 gm%)
• In adults
- Male: 13.5-18 gm% (Avg-15.5 gm%)
- Female: 11-16 gm% (Avg-14 gm%)
2. RBC count
• At birth: 6-7 million/cumm of blood
• In adults
- Male
: 5-6 million/cumm of blood
- Female : 4.5-5.5 million/cumm of blood
3. WBC count (Total)
• At birth : 20000/cumm of blood
• In adults: 4000-11000/cumm of blood
4. WBC count (Differential)
• Neutrophil : 50-70%
• Eosinophil : 1-4%
• Basophil
: < 1%
• Lymphocyte : 20-40%
• Monocyte : 2-8%
5. WBC count (Absolute)
• Neutrophil : 3000-6000/cumm of blood
• Eosinophil : 150-300/cumm of blood
• Basophil
: 10-100/cumm of blood
• Lymphocyte : 1500-2700/cumm of blood
• Monocyte
: 300-600/cumm of blood
6. Reticulocyte count: 24000-84000/cumm of blood
7. Platelet count : 2-5 lacs/cumm of blood
SECTION III : APPENDIX
IMPORTANT VALUES TO REMEMBER 253
8. ESR
• Westergren
- Male : 3- 5 mm in 1st hour
- Female : 5-7 mm in 1st hour
• Wintrobe’s
- Male : 0-10 mm in 1st hour
- Female : 0-20 mm in 1st hour
9. RBC indices
• PCV (Hct):
- Male : 40-50%
- Female : 36-47%
• MCV
: 78-94 µm3
• MCH
: 27-32 pg
• MCHC
: 30-38%
• CI
: 0.85-1.15
10. Fragility of red cells
• Hemolysis begins
: 0.5% NaCl
• Hemolysis completes : 0.36% NaCl
11. Bleeding time
• Duke’s method : 2-5 min
• Ivy’s method
: 3-9 min
12. Coagulation time
• Capillary blood (Capillary glass tube method): 3-8 min
• Venous blood (Lee and White method) : 5-15 min
13. Prothrombin time : 14-18 sec
14. Total blood volume : 5-6 L
15. Specific gravity
• Of blood : 1.048-1.066
• Of RBC : 1.092-1.095
• Of plasma : 1.026-1.035
16. Frequency distribution of blood group in INDIA
• A blood group
: 21%
• B blood group : 39%
• AB blood group : 9%
• O blood group : 31%
• Rh positive
: 95%
• Rh negative
: 5%
254 VIVA IN MEDICAL PHYSIOLOGY
II. Plasma/Serum
1. Plasma volume
• Male: 39 ml/ kgbw
• Female: 40 ml/kgbw
2. Osmolality:
• Plasma: 285-295 mosm/kg of serum water
• ECF: 3000 mosm/L
• ICF : 300 mosm/L
3. NPN Substances: 20-30 mg/dl
4. Proteins (Total): 5.5-8 gm/dl
• Albumin: 3.5-5 gm/dl
• Globulin: 2-3.5 gm/dl
• Fibrinogen: 0.2-0.5 gm/dl
5. Amino acids: 6-8 gm/dl
6. Total lipid: 450-1000 mg/dl
7. Cholesterol:120-220 mg/dl
8. Fatty acids: 160-270 mg/dl
9. Triglycerides: 25-150 mg/dl
10. Glucose
• Fasting: 80-110 mg/dl
• Post-prandial
- Normal: 140 mg/dl
- Diabetic :> 200 mg/dl
11. Sodium: 135-145 mEq/L
12. Potassium: 3.5-5 mEq/L
13. Chloride: 95-108 mEq/L
14. Bicarbonate: 26-28 mmol/L
15. Calcium : 2.12- 2.62 mEq/l
: 8.5-10.5 mg/dl
16. Magnesium: 2-3 mg/dl
: 1.5-2.0 mEq/L
17. Phosphate : 2.5-4.5 mg/dl
18. Amylase : 13-53 nmol/L
: 60-180 Somogyi unit/dl
19. SGOT: 100-300 μmol/L
20. SGPT: 50-430 μmol/L
21. Alkaline phosphatase: 0.4-1.5 μmol/L
SECTION III : APPENDIX
IMPORTANT VALUES TO REMEMBER 255
22. Bilirubin
• Total (Indirect): Up to 1 mg/dl
• Conjugated (direct): Up to 0.4 mg/dl
23. Creatinin: 0.6-1.5 mg/dl
24. Urea: 20-40 mg/dl
25. Uric acid
• Male: 3.6-8.5 mg/dl
• Female: 2.3-6.6 mg/dl
26. Protein bound iodide: 3.5-8 μg/dl
27. Thyroid binding globulin: 7-17 mg/L
28. Thyroxin: 70-140 nmol/L
29. Tri-iodothyronine: 1.2-3.0 nmol/L
III. Cardiovascular System
1. Pressure inside the heart (in mm Hg)
• Right Atrium: 0-8
• Right ventricle (Systolic): 15-30
• Right ventricle (Diastolic): 0-8
• Left ventricle (Systolic/Aortic): >150
• Left ventricle (End diastolic): 3-12
• Pulmonary artery (Systolic): 15-30
• Pulmonary artery (End diastolic): 3-12
• Pulmonary capillary: 8
2. Capillary pressure (systemic)
Arterial end: 32 mm Hg
Venous end: 12 mm Hg
Mean: 20 mm Hg
3. Heart rate (resting)
• In adult: 60-90 beat/min
In infant: 120-140 beat/min
4. Arterial BP (Resting)
Systolic: 110-140 mm Hg
Diastolic: 60-90 mm Hg
Mean: 100 mm Hg
5. Cardiac output: 5-6lit/min
6. Cardiac Index: 2.5-3.6 lit/min/m2 BSA
7. Stroke volume index: 40 ml/sq.m /beat
256 VIVA IN MEDICAL PHYSIOLOGY
8.
9.
10.
11.
12.
13.
14.
Stroke volume: 70-90 ml
End systolic volume: 50 ml
End diastolic volume: 130 ml
Coronary blood flow: 225 ml/min
Cerebral blood flow: 750 ml/min
Renal blood flow: 1300 ml/min
Circulation time:
Arm to tongue (saccharin): 14.2 ± 2.4 sec
Arm to lung (ether): 4-8 sec
Arm to foot (radiosodium): 15-105 sec.
IV. Respiratory System
1. Inspired air (Atmospheric air)
Gas
Percentage
Partial pressure (mmHg)
O2
20.96
160
CO2
0.04
0.15
N2
79
600
2. Alveolar air
O2
13.2
101
CO2
5.3
40
N2
75.3
572
Water
6.2
47
3. Expired air
O2
15.5
116.5
CO2
3.6
27.5
N2
74
569
Water
6.2
47
4. Arterial blood
O2
19.3
100
CO2
48
40
5. Venous blood
O2
14.1
40
CO2
52
46
6. Respiratory rate: 12-18 breaths/min
7. Respiratory quotient: 0.8
8. O2 consumption at rest: 250 ml/min
SECTION III : APPENDIX
IMPORTANT VALUES TO REMEMBER 257
9. O2 diffusion capacity
In male : 27-42 ml/min/mmHg
In female : 28-30 ml/min/mmHg
10. Tidal volume: 500-800 ml
11. Inspiratory reserve volume: 2000-3300 ml
12. Expiratory reserve volume: 1100 ml
13. Residual volume: 1200 ml
14. Inspiratory capacity: 3500 ml
15. Expiratory capacity: 1600 ml
16. Functional residual capacity: 2200 ml
17. Vital capacity
In male : 4500-5500 ml
In female : 3500-4500 ml
18. Total lung capacity: 5700 ml
19. Pulmonary ventilation (RMV): 6-7 lit/min
20. Alveolar ventilation: 4.9 lit/min
21. Maximum voluntary ventilation:
• In male : 150-170 lit/min
• In female : 80-100 lit/min
22. FEV1: 75-85%
23. Doesponic index: 60-70 %
24. Respiratory dead space volume: 150 ml
25. Lung compliance:
• Lungs alone : 220 ml/cm of water
• Lungs and Thorax : 130 ml/cm of water
26. O2 transported through plasma: 0.3 ml/100 ml of blood/
100 mmHg PO2
27. O2 carrying capacity of blood: 20 ml of O2
28. CO2 transport
Through plasma: 0.3 ml/100 ml of blood (7%)
• Through bicarbonate: 3 ml/100 ml of blood (70%)
• Through carbamino compound: 0.7 ml/100 ml of blood
(0.7%)
V. Excretory System
1. No. of nephron/Kidney: 1 million
2. GFR : 125 ml/min (180 L/day)
258 VIVA IN MEDICAL PHYSIOLOGY
3. Renal fraction: 12-30%
4. TmG of glucose:
In male: 300-450 mg/min
In female: 250-350 mg/min
5. Inulin clearence:
In male: 124 ± 25.8 ml/min
In female: 119 ± 12.8 ml/min
6. Creatinine clearence: 91-130 ml/min
7. PAH clearence (Renal plasma flow):
In male: 560 ± 630 ml/min
In female: 490 ± 700 ml/min
8. Urea clearence:
Maximal clearence : 60-90 ml/min
Standard clearence : 40-65 ml/min
VI. Reproductive System
1. Volume of semen: 3.1 ml
2. Fructose content of semen: 40-400 mg /dl
3. Duration of spermatogenesis: approx. 74 days
4. Testosterone production: 10 mg/day
5. Duration of menstrual cycle: 28 ± 4 days
6. Duration of menstrual blood flow: 3-5 days
7. Menstrual blood loss: 10-55 ml
8. Menarche: 9-16 years
9. Menopause: 45-50 years
10. Gestational period: 280 days
VII. Cerebrospinal fluid:
1. Volume : 100-150 ml
2. Pressure:
• In Newborn: 30-80 mm of water
• In adult : 70-200 mm of water
3. Glucose content: 40-80 mg /dl
4. Rate of formation of CSF: 500-800 ml/day