THE UNIVERSITY OF ZAMBIA
SCHOOL OF MEDICINE
DEPARTMENT OF PHYSIOLOGICAL SCIENCES
SEMESTER II FINAL EXAMINATION – MARCH 2011
MEDICAL PHYSIOLOGY
PGY 312
PAPER II
DURATION:
THREE (3) HOURS
COMPUTER NO.: …………………………………….
INSTRUCTIONS TO CANDIDATES
1.
Use the special MCQ answer sheet provided.
2.
Write your computer number on both the question
paper and answer sheet.
3.
Carefully follow the instruction pertaining to each
section.
Section A
In the following questions (1 - 40) select the one most appropriate answer.
Each question carries 1 mark.
1.
Under physiological conditions capillary exchange is controlled mainly by:
(a)
(b)
(c)
(d)
(e)
2.
If total body oxygen consumption is 150 ml/min and the arterial and mixed
venous O2/100 ml blood, respectively, the cardiac output is:
(a)
(b)
(c)
(d)
(e)
3.
The force-velocity relation of cardiac muscle
Poiseuille’s Law of he heart
The length-tension diagram of cardiac muscle
Laplace’s Law of the heart
Excitation-contraction coupling of cardiac muscle
The principal factor that limits exercise performance is:
(a)
(b)
(c)
(d)
(e)
5.
5000 ml/min
1000 ml/min
100 ml/min
5 ml/min
0.5 ml/min
The Frank-Starling relation is essentially a restatement of:
(a)
(b)
(c)
(d)
(e)
4.
Capillary permeability
Plasma oncotic pressure
Vascular smooth muscle contraction
Tissue hydrostatic pressure
Lymphatic drainage
Rate of respiration
Depth of respiration
Pumping capacity of the heart
Oxygen consumption by the active muscles
Oxygen saturation of arterial blood
Lymph flow decreases in response to:
(a)
(b)
(c)
(d)
(e)
Exercise
Hemorrhage
Protein leakage from capillaries
Increased venous pressure
Increased arterial pressure
1
6.
The most important factor that regulates coronary blood flow is:
(a)
(b)
(c)
(d)
(e)
7.
In response to an increase in carotid sinus pressure, the peripheral arterioles
are dilated mainly by:
(a)
(b)
(c)
(d)
(e)
8.
Local dilator agents, such as lactic acid and CO2
Increased activity of sympathetic vasodilator fibers
Increased activity of parasympathetic vasodilator fibers
Decreased activity of sympathetic vasoconstrictor fibers
Increased stimulation of alpha-adrenergic receptors
The most important function of the Starling mechanism in the heart is:
(a)
(b)
(c)
(d)
(e)
9.
Neural regulation by the autonomic nervous system
The intraventricular pressure during ventricular systole
Autoregulation caused by local chemical factors
The aortic blood pressure
Circulating epinephrine
To provide an adequate cardiac output during sustained exercise
To ensure that the ventricles operate at an optimum length
To couple the efficiency of muscle contraction to the heart rate
To match the output of one ventricle to that of the other
To ensure that right and left atrial pressures are equal
The segment of the vascular bed responsible for local regulation of blood
flow in most tissues is the:
(a)
(b)
(c)
(d)
(e)
Distributing arteries
Large veins
Capillaries
Venules
Arterioles
10. The arteriovenous shunts in the skin:
(a)
(b)
(c)
(d)
(e)
Are insensitive to circulating catecholamines
Possess a high degree of basal tone
Dilate maximally when denervated
Are less sensitive to sympathetic stimulation than are muscle arterioles
Dilate in response to cooling of the hypothalamus
2
11. The medullar vasomotor center is stimulated most effectively by:
(a)
(b)
(c)
(d)
(e)
Decreased arterial blood oxygen tension
Decreased arterial blood hydrogen ion concentration
Increased arterial blood adenosine concentration
Increased arterial blood carbon dioxide tension
Increased arterial blood potassium ion concentration
12. A reduction in arterial compliance results in:
(a)
(b)
(c)
(d)
(e)
A rise in systolic arterial pressure but a reduction in mean arterial
pressure
A rise in systolic and in mean arterial pressure
A fall in systolic but a rise in diastolic arterial pressure
A rise in systolic and an even grater rise in diastolic arterial pressure
A rise in systolic but no significant change in mean arterial pressure
13. Cardiac output (in liters per minute) divided by he heart rate (in beats per
minute) equals:
(a)
(b)
(c)
(d)
(e)
Cardiac index
Cardiac efficiency
Mean arterial pressure
Stroke volume
Blood velocity
14. The circulatory variable that is maintained relatively constant by the
baroreceptor reflex is:
(a)
(b)
(c)
(d)
(e)
Heart rate
Stroke volume
Peripheral resistance
Velocity of blood flow
Mean arterial pressure
15. The contribution of atrial contraction to ventricular filling is greatest:
(a)
(b)
(c)
(d)
(e)
When vagal activity is pronounced
At rapid heart rates
When atria and ventricles contract simultaneously
During atrial flutter
During third-degree AV block
3
16. The increase in arterial pulse pressure usually observed in an elderly
hypertensive person is produced mainly by:
(a)
(b)
(c)
(d)
(e)
An increases stroke volume
An increased heart rate
A decreased cardiac output
An increased vagal activity
A decreased arterial compliance
17. During the steady, laminar flow of newtonian fluid through a cylindrical tube,
if the tube radius is tripled, flow will:
(a)
(b)
(c)
(d)
(e)
Decrease by two thirds
Remain unchanged
Increase 3-fold
Increase 9-fold
Increase 91-fold
18. Injection of a drug that specifically increases ventricular contractility will
decrease:
(a)
(b)
(c)
(d)
(e)
Central venous pressure
Mean arterial pressure
Arterial pulse pressure
Capillary blood flow
Stroke volume
19. The principal determinants of mean arterial pressure are:
(a)
(b)
(c)
(d)
(e)
Cardiac output and peripheral resistance
Arterial and venous capacitance
Cardiac output and arterial capacitance
Peripheral resistance and arterial capacitance
Cardiac output and venous capacitance
20. Conduction velocity of the cardiac impulse is slowest in:
(a)
(b)
(c)
(d)
(e)
Atrial myocardial fibers
AV modal fibers
Purkinje fibers
Ventricular myocardial fibers
His bundles fibers
4
21. If the diaphragm contracts more vigorously, it is likely to the slowly adapting
lung stretch receptor activity will:
(a)
(b)
(c)
(d)
(e)
Increase inspiratory volume
Be greater than normal
Be less than normal
Be the same as normal
Cause the time for inspiration to lengthen
22. The normal regulation of local perfusion to lung ventilation units depends
mainly upon:
(a)
(b)
(c)
(d)
(e)
Alveolar CO2 Tension
The mixed venous blood pulmonary arterial) hydrogen ion
concentration (pH)
Alveolar O2 tension
The mixed venous blood (pulmonary arterial O2 tension
The balance between sympathetic neural stimulation of vascular
smooth muscle and parasympathetic stimulation of airway smooth
muscle
23. The normal resting oxygen consumption of adult humans is determined by
the:
(a)
(b)
(c)
(d)
(e)
Fact that resting cardiac output is about 5 L/min, thereby limiting blood
flow to some organs
Ability of tissues cells to extract oxygen from the capillaries blood in
the time available exchange in the capillaries
Ability of pulmonary capillary blood to take up oxygen from alveolar
gas in the time available (less than 1 second) for exchange
Fact that the P50 of adult human blood is normally 26 to 29 mm Hg,
meaning that no more than 50% of the total blood oxygen
concentration is available for cellular oxidative metabolism
Oxidative energy requirements of the body’s cells, which are always
met in the steady state
5
24. Normal inspiration is limited by:
(a)
(b)
(c)
(d)
(e)
Sensory feedback to the respiratory centers in the medulla
(brainsterm) from mechanoreceptors in the chest wall and lung and
various chemoreceptors sensitive to oxygen and carbon dioxide
The breathing frequency, about 12/min in resting adult humans, which
limits each breath to 5 seconds’ duration
The rise of abdominal pressure as the diaphragm contracts, especially
in the supine (dorsa recumbent) position, when the weight of
abdominal contents pushes up on the diaphragm and tends to reduce
end-expiratory lung volume
The rise in pleural pressure as lung volume increases
The mechanical limits of the chest wall (rib cage and diaphragm),
which limits the maximal size of the thoracic cavity.
25. There are several factors controlling adult human respiration on a momentto-moment basis. Those which is of importance include:
(a)
(b)
(c)
(d)
(e)
Pulmonary stretch reflexes
Systemic arterial pCO2 on carotid and aortic chemoreceptors
PCO2 of CNS capillary blood on chemosensors of the medulla
Cerebrospinal fluid pH
All are correct
26. The diaphragm
(a)
(b)
(c)
(d)
(e)
Decreases the volume of the thoracic space when it contracts
Decreases intrathoracic pressure when it contracts
Is innervated by the vagus nerve
Increases intrathoracic pressure when it contracts
B and D are correct
27. Lung surfactant:
(a)
(b)
(c)
(d)
(e)
Decreases the likelihood of alveolar collapse during expiration
Facilitates O2 diffusion through alveolar membranes
Facilitates CO2 diffusion through alveolar membranes
Increases surface tension of the alveolar membrane
A and C are correct
6
28. Central chemoreceptor drive constitutes an important compensatory
mechanism in:
(a)
(b)
(c)
(d)
(e)
Anemia
Methemoglobinemia
Carbon monoxide poisoning
Emphysema
B and D are correct
29. The pontine respiratory center has:
(a)
(b)
(c)
(d)
(e)
Its effects through a cortical-medullary reflex arc
An area that will cause prolonged expiration if stimulated
An area that is primarily active in controlling the rate of respiration
Afferents directly to motoneurons necessary for respiration
A and C are correct
30. The total oxygen in the blood will:
(a)
(b)
(c)
(d)
(e)
Be most closely related to the pO2 of the blood
Be most closely related to the hemoglobin content
Not be reduced in hypoxia
Be increased in anemia
None are correct
31. Oxygen release from hemoglobin is caused and enhanced by:
(a)
(b)
(c)
(d)
(e)
Low temperature in the tissues
High pCO2 in the tissues
High pH in the tissues
Low pO2 in the tissues
B and D are correct
32. Hemoglobin is particularly well suited to carry oxygen in the blood. Its
advantages in the human include:
(a)
(b)
(c)
(d)
(e)
The leftward shift in affinity that results from acid conditions
A greater affinity for O2 than for results from acid conditions
An easily reversible binding with O2
The ability to give up most of its oxygen at pO 2 between 5 and 20 mm
Hg
A and C are correct
7
33. During a maximal inspiratory event:
(a)
(b)
(c)
(d)
(e)
Force generation of the muscles of inspiration increases
The transmural pressure remains low
The pleural pressure is subatmospheric
Flow rate remains high, but only over a narrow range of lung volumes
All are correct
34. The elastic recoil of the chest wall:
(a)
(b)
(c)
(d)
(e)
Is directed inward at end-inspiration
Is directed outward at functional residual capacity
Is opposed by the recoil of the lungs
Is approximately 70% of lung capacity at equilibrium
All are correct
35 Functional residual capacity is:
(a)
(b)
(c)
(d)
(e)
The volume of air exhaled during exhalation
The amount of air left in the lungs at the end of normal, resting
expiration
The volume of air inhaled during respiration
The maximal amount of air that can be exhaled after quiet expiration
None of the above
36 The periodic nature of normal respiration is fundamentally caused by:
(a)
(b)
(c)
(d)
(e)
Intermittent bursts of activity from cells in the pontine “apneustic center”
Feedback loops involving the peripheral chemoceptors
Coupled oscillatory behaviour of inspiratory and expiratory cells in the
medulla
“Pneumotaxic center”
Conscious control from areas of the motor cortex
37. The primary stimulus of respiration is a:
(a)
(b)
(c)
(d)
(e)
Two-fold increase in the pCO2 of inspired air
Two-fold increase in the pO2 of inspired air
50% decrease in the pCO2 of inspired air
50% increase in the pO2 inspired air
50% decrease in pCO2
8
38. Which of the following is responsible for the movement of O2 from the
alveoli into the blood in the pulmonary capillaries?
(a)
(b)
(c)
(d)
(e)
Active transport
Filtration
Secondary active transport
Facilitated diffusion
Passive diffusion
39. Which of the following has the greatest effect on the ability of blood to
transport oxygen?
(a)
(b)
(c)
(d)
(e)
The capacity of the blood to dissolve oxygen
The amount of hemoglobin in the blood
The pH of plasma
The CO2 content of red blood cells
The temperature of the blood
40. Which of the following has the greatest buffering capacity in the interstitial
fluid?
(a)
(b)
(c)
(d)
(e)
The hemoglobin system
The bicarbonate system
The phosphate system
The protein in the interstitial fluid
The ammonium-ammonia system
SECTION B
In the following questions (41 – 120) each consists of a stem and four
statements. Write ‘T’ or ‘F’ if the statement is true/false respectively
against the letters a, b, c, d corresponding to the statement. Each question
carries 2 marks. ¼ mark will be deducted for incorrect judgment.
41.
It may be concluded that arterioles offer more resistance to blood than
other blood vessels because:
(a)
(b)
(c)
(d)
They have thick muscular walls
They have a rich sympathetic innervation
They have a smallest internal diameters
The pressure drop across them is greater than that across the
arteries, the capillaries and veins
9
42.
The following are statements about vasomotor nerve fibres:
(a)
(b)
(c)
(d)
43.
The causes of syncope (fainting) include:
(a)
(b)
(c)
(d)
44.
Pulmonary blood flow is measured
The PO2 of arterial and mixed venous blood are measured
Oxygen uptake is estimated from alveolar PO2 measurements
Pulmonary venous blood is sampled to measure the oxygen in
arterial blood
What are the consequences of arteriolar vasoconstriction in an organ?
(a)
(b)
(c)
(d)
46.
Pressure on the carotid sinus
Autonomic insufficiency
Strong emotion
Complete heart block with ventricular asystole
In the estimation of cardiac output using the Fick Principle:
(a)
(b)
(c)
(d)
45.
Sympathetic vasoconstrictor nerve fibres supply the smooth muscle
in the walls of the arterioles almost everywhere in the body
The transmitter released by vasoconstrictor nerve fibres is
noradrenaline
There are also sympathetic vasodilator nerve fibres that supply
arterioles in the muscle
The transmitter released by these vasodilator nerve fibres is
adrenaline
A decrease in the rate of O2 utilization
An increase in the partial pressure of CO2 in blood leaving the
organ
A reduction in blood flow through the organ
A decrease in the arterio-venous oxygen difference
The velocity of blood flow:
(a)
(b)
(c)
(d)
Is increased in a constricted area of a blood vessel
Is higher in the capillaries, because the total cross-sectional area of
the capillaries is large
Is lower at the center than at the periphery of the stream of blood in
a large blood vessel
Is lower in the veins than in the venules
10
47.
The following are important variables in circulatory physiology: Cardiac
output (CO); Total peripheral resistance (TPR), mean arterial blood
pressure (BP); stroke volume, (SV); heart rate (HR); are the following
relationships true or not?
(a)
(b)
(c)
(d)
48.
(b)
(c)
(d)
(b)
(c)
(d)
Effective filtration pressure (EFP) = Hydrostatic pressure – tissue
pressure
Osmotic pressure gradient (OPG) = Plasma osmotic pressure –
tissue osmotic pressure
When EFP > OPG absorption take place
Pulmonary capillaries filter more fluid then systemic ones
The most important controlling mechanism of cerebral blood flow is
the sympathetic system
Stimulation of the cardiac nerves causes coronary arteriolar dilation
The blood flow to the lungs can be measured by using clearance of
oxygen
During exercise the coronary blood four can rise significantly
Which of the following functions would be disrupted by a gallstone locking
the common bile duct?
(a)
(b)
(c)
(d)
51.
CO X TPR
BP/TPR
SV X HR
HR/SV X TPR
Statements on regional circulation:
(a)
50.
=
=
=
=
Capillary function:
(a)
49.
BP
CO
CO
CO
Formation of the micelles involved in fat absorption in the intestine
Emulsification of fats in the intestine
Removal of cholesterol from the circulation
Absorption of carbohydrates
The mean QRS vector (electrical axis of the heart) in the frontal plane:
(a)
(b)
(c)
(d)
Can be determined from 3 standard limb leads
Is normally the same during systole and diastole
Is of value in determining whether left or right axis deviation is
present
May be reversed in essential hypertension
11
52.
In complete heart block:
(a)
(b)
(c)
(d)
53.
Reentry is a common cause of:
(a)
(b)
(c)
(d)
54.
The appearance of Q waves that were not previously present
A short PR interval
Elevation of ST segments in some leads
Bradycardia
In which of the following arrhythmias would you expect drugs that increase
the refractory period of conduction tissue and muscle fibers to be of
therapeutic value?
(a)
(b)
(c)
(d)
56.
Paroxysmal atrial tachycardia
Paroxysmal nodal tachycardia
Atrial fibrillation
Sinus arrhythmia
Which of the following electrocardiographic changes are characteristic of
myocardial infarction?
(a)
(b)
(c)
(d)
55.
Fainting may occur because the atria are unable to pump blood into
the ventricles
Fainting may occur because of prolonged period during which the
ventricles fail to contract
The atrial rate is slower than the ventricular rate
The ventricular rate is slower than the atrial rate
Atrial fibrillation
Paroxysmal atrial tachycardia
Paroxysmal ventricular tachycardia
Ventricular fibrillation
Activity in sympathetic nerves to the heart is decreased:
(a)
(b)
(c)
(d)
During excitement
When blood pressure is suddenly increased by infusion of
norepinephrine
During hypoxia
Immediately after lying down from a standing position
12
57.
Blood pressure rises with:
(a)
(b)
(c)
(d)
58.
Blood pressure falls with:
(a)
(b)
(c)
(d)
59.
Increase the contractility of cardiac muscle
Increase the rate of discharge of the sinoatrial node
Increase cardiac output
Have no effect on blood pressure
The coronary arteries are:
(a)
(b)
(c)
(d)
62.
Potassium ions
Carbon dioxide
Hydrogen ions
Histamine
Catecholamines acting on -adrenergic receptors:
(a)
(b)
(c)
(d)
61.
Low oxygen tension in the medulla oblongata
Administration of atropine, a drug that block muscarinic cholinergic
receptors
Occlusion of the carotid arteries in the neck
Stimulation of the vagus nerves that innervate the atria and great
veins
Blood flow in capillaries is increased by the local action of:
(a)
(b)
(c)
(d)
60.
Stimulation of the nerves from the aortic bodies
Stimulation of pain fibers from the abdomen
An increase in cardiac output
Stimulation of the receptors from the carotid sinus
Dilated by adenosine
Constricted by a direct effect of norepinephrine
Dilated by an indirect effect of norepinephrine
Contricted by acetylcholine
Arterioles in the skin dilate when exposed to:
(a)
(b)
(c)
(d)
Increased body temperature
Epinephrine
Bradykinin
Vasopressin
13
63.
Which of the following are important blood reservoirs that can help provide
extra circulating arterial blood during emergencies?
(a)
(b)
(c)
(d)
64.
Which of the following cause contraction of brochial smooth muscle?
(a)
(b)
(c)
(d)
65.
Transection of both phrenic nerves
Transection of the spinal cord of the first thoracic level
A large dose of morphine
Pulmonary fibrosis
Pulmonary diffusing capacity for O2 is dependent on the:
(a)
(b)
(c)
(d)
68.
Intra-abdominal pressure
Venous return to the heart
Heart rate
Intrapleural pressure
Which of the following would be expected to cause a reduction in
pulmonary ventilation?
(a)
(b)
(c)
(d)
67.
Leukotrienes
Vasoactive intestine peptide (VIP)
Acetylcholine
Epinephrine
During inspiration, there is an increase in:
(a)
(b)
(c)
(d)
66.
The skin
The splanchinic region
The lungs
The brain
PO2 of blood in the pulmonary vein
Thickness of the alveolar capillary membrane
Total area of alveoli apposed to capillaries
Hemoglobin concentration of blood in pulmonary capillaries
The flow of O2 from blood to the tissues is increased by a decrease in:
(a)
(b)
(c)
(d)
The 2, 3-DPG content of the blood
Blood PCO2
Plasma Na+ concentration
Plasma pH
14
69.
The concentration of 2, 3-DPG in peripheral blood:
(a)
(b)
(c)
(d)
70.
Injection of a drug that stimulates the carotid bodies would be expected to
cause:
(a)
(b)
(c)
(d)
71.
Decrease the blood pressure
Increase the heart rate
Inhibit inspiration
Facilitate inspiration
The respiratory center:
(a)
(b)
(c)
(d)
73.
A decrease in the pH of arterial blood
An increase in the PO2 of arterial blood
An increase in the HCO3- concentration of arterial blood
A decrease in the H+ concentration of arterial blood
Stimulation of the central (proximal) end of a cut vagus nerve would be
expected to:
(a)
(b)
(c)
(d)
72.
Determines in part the affinity of hemoglobin for O2
Increases in chronic hypoxia
Decreases when the H+ concentration in red cells increases
Is unaffected by exercise
Sends out regular bursts of impulses to expiratory muscles during
quiet respiration
Is unaffected by stimulation of pain receptors
Is located in the pons and midbrain
Sends out regular bursts of impulses to inspiratory muscles during
quiet respiration
The stimulation of respiration is relatively slight when the PO2:
(a)
(b)
(c)
(d)
There is a compensatory increase in alveolar PO2
There is a slight increase in the pH of arterial blood that tends to
inhibit respiration
The threshold arterial PO2 at which the chemoreceptors are
stimulated is 50 mm Hg
There is a decrease in alveolar PCO2
15
74.
Variations in which of the following components of blood or cerebrospinal
fluid affect respiration?
(a)
(b)
(c)
(d)
75.
O2 delivery from the blood to exercising muscle is facilitated by:
(a)
(b)
(c)
(d)
76.
(b)
(c)
(d)
Muscle blood flow increases partly due to increased
parasympathetic vasodilator nerve discharge
Muscle blood flow increases partly as a consequence of the local
release of vasodilator metabolites
Pulmonary vascular resistance decreases
The increase in cardiac output observed on exercise is largely
brought about the Starling mechanism
During normal quiet tidal breathing:
(a)
(b)
(c)
(d)
78.
Increased 2, 3-DPG concentrations in red blood cells
Increased tissue temperature
Decreased tissue pH
Low tissue PO2
During prolonged exercise the following cardiovascular adjustments take
place:
(a)
77.
Arterial K+ concentration
Arterial H+ concentration
Arterial NH3 concentration
Cerebrospinal fluid CO2 concentration
The dome of the diaphragm hardly moves at all
The upper external intercostals muscles help aerate the bases of
the lungs
There is a decrease in both intrapleural and intra-alveolar pressure
during the inspiratory phase
The actual amount of air shifted each time by an adult is about
250ml
The intra-alveolar (IA) and intrapleural (IP) pressures:
(a)
(b)
(c)
(d)
In normal quiet expiration the IP pressure remains subatmospheric
In the upright position there is a marked difference in IP at the
bases and apices of the lungs
In normal people the IA pressure always exceeds the IP pressure
Intra-alveolar pressure similar to that in the dorsal oesophagus
16
79.
Concerning volumes and capacities:
(a)
(b)
(c)
(d)
80.
In measuring pulmonary function:
(a)
(b)
(c)
(d)
81.
During exercise the respiratory rate can rise to about 55/min
Maximum breathing capacity (MBC) should be more than 10 times
the resting minute volume (RMV)
Functional residual capacity is measured with a simple BenedictRoth spirometer
A normal person can fully expire in less than 1 s
The functional residual capacity (FRC):
(a)
(b)
(c)
(d)
82.
The vital capacity (VC) can be used to monitor heart failure
The VC falls significantly on recumbency in normal people
The VC is a good screening test of lung function
The residual volume (RV) is exhaled in maximal expiration
Falls markedly as one gets older
Is increased in emphysema
Rises in recumbency
Should normally be about 40% of the total lung capacity (TLC)
Increased sympathetic drive to the heart increases the:
(a)
(b)
(c)
(d)
Rate of diastolic depolarization in sinoatrial node cells
Coronary blood flow
Rate of conduction in Purkinje tissue
Ejection fraction of the left ventricle
83.
In the electrocardiogram, the:
84.
(a)
QRS complex follows the onset of ventricular contraction
(b)
T wave is due to repolarization of the ventricles
(c)
PR interval corresponds with atrial depolarization
(d)
RT interval is related to ventricular action potential duration
The strength of contraction of left ventricular muscle increases when:
(a)
(b)
(c)
(d)
Serum potassium levels rise
Blood calcium levels falls
Strenuous exercise is undertaken
Peripheral resistance is increased
17
85.
The linear velocity of blood flow:
(a)
(b)
(c)
(d)
86.
Oxygen debt:
(a)
(b)
(c)
(d)
87.
Chronic renal failure
Periods when plasma bicarbonate level is raised
Deep sleep
Exercise because of the ensuing fall in arterial PO2
Compliance of the lungs is greater:
(a)
(b)
(c)
(d)
90.
The volume of air expired from full inspiration to full expiration
Reduced as one grows older
Greater in men than in women of the same age and height
The sum of the inspiratory and expiratory reserve volumes
Ventilation is increased during:
(a)
(b)
(c)
(d)
89.
The amount of O2 consumed after cessation of exercise
Possible since skeletal muscle can function temporarily without
oxygen
Associated with a rise in blood lactate
Associated with metabolic acidosis
Vital capacity is:
(a)
(b)
(c)
(d)
88.
Is higher in the capillaries than in the arteries because the total
cross sectional area of the capillaries is larger than that of the
arteries
Is lower in veins than in the venules
Falls to zero in the descending aorta during diastole
Is increased in a constricted area of a blood
When they are expanded above their normal tidal volume range
In adults than in infants
Than the compliance of the lungs and thorax together
In standing than in recumbent subjects
The following are statements about the respiratory center
(a)
(b)
(c)
(d)
Is in the hypothalamus
Sends impulses to expiratory muscles during quiet breathing
Is involved in the swallowing reflex
Is not involved in the vomiting reflex
18
91.
This question concerns the peripheral and central nervous control of
breathing:
(a)
(b)
(c)
(d)
92.
During normal quiet tidal breathing:
(a)
(b)
(c)
(d)
93.
There is a decrease in both intrapleural and intra-alveolar pressure
during the inspiratory phase
The actual amount of air shifted each time by an adult is about
250ml
A paralysis of the external intercostal muscles reduces the tidal
volume by about 30%
The apper external intercostal muscles help create the bases of the
lungs
Concerning control of the coronary circulation:
(a)
(b)
(c)
(d)
94.
Neurons in the CNS which show a strong respiratory rhythm are
found predominantly in the pons
Section of the vagal nerves would show the rate of breathing
Specialized neurons in the medulla which act as chemoreceptors
detect changes in the partial pressure of oxygen
A spinal cord transection at C6 would prevent breathing
Coronary vessels are poorly supplied with sympathetic nerves
Vagal nerve stimulation dilated coronary resistance vessels
Hypoxia directly relaxes coronary resistance vessels
A fall in pH relaxes coronary vessels significantly
The following are statements about the surface active material
(surfactant):
(a)
(b)
(c)
(d)
Surfactant increases lung compliance
The surfactant increases the surface tension of film of liquid living
the alveoli
In the absence of normal surfactant there will be a greater tendency
for alveoli to collapse
The surface tension of fluid containing surfactant increases as the
surface area of fluid decreases
19
95.
Concerning peripheral chemoreceptors:
(a)
(b)
(c)
(d)
96.
The closing volume of the lungs:
(a)
(b)
(c)
(d)
97.
(b)
(c)
(d)
One can measure the alveolar DS by N2 analysis of expired air after
inhaling 100% nitrogen
At rest the anatomical and alveolar DS have roughly equal volumes
The alveolar DS becomes very large in exercise in normal people
The volume of the anatomical DS alters during a ventilatory cycle
In the mechanics of breathing:
(a)
(b)
(c)
(d)
99.
Is the volume of air expired before close off
If it equals the tidal volume is incompatible with the life
Is associated with the closure of airways in the apex of the lung
before closure elsewhere
Increases in recumbency
Dead Space (DS):
(a)
98.
The carotid and aortic bodies are about equal importance in man
Chemoreceptor activity increases in acute haemorrhage
Stimulation of chemoreceptors causes vasodilatation in pulmonary
blood vessel
Stimulation of chemoreceptors causes vasodilation in pulmonary
blood vessels
The compliance is given by volume/pressure (V/P)
The compliance of the thorax decreases in obesity
The compliance of lungs is about the same as that of the thoracic
cage in young healthy adults
An estimate of elastic forces is given by area between inspiratory
and expiratory traces on the hysteresis loop
Gas diffusion in the lungs:
(a)
(b)
(c)
(d)
CO2 diffuses better than O2 within the alveolus
O2 transfer is perfusion-dependent
Diffusion can be increased voluntarily in normal people
It is independent of the solubility of the gas in the alveolar capillary
membrane
20
100.
Pulmonary ventilation/perfusion (V:Q) ratio:
(a)
(b)
(c)
(d)
101.
Gas exchange in the lungs:
(a)
(b)
(c)
(d)
102.
Airway resistance is the main component in the work of breathing
Over half the airway resistance is in the very small airways
Elastic fibres are difficult to stretch
Collagen contributes to the elastic resistance of the lungs
During the respiratory cycle:
(a)
(b)
(c)
(d)
104.
CO2 combines about 25 times more avidly with HB that O2
The diffusion of CO2 and O2 across the alveolar membrane is
inversely proportional to the thickness of that membrane
The transmit time of red cells in the pulmonary circuit is about 4s
It takes about 2s for full diffusion of O2 and CO2 to occur
Concerning the work of breathing:
(a)
(b)
(c)
(d)
103.
In the upright position the normal V:Q ratio causes blood causes
blood from the lung apex to be less than fully oxygenated
Giving O2 improves hypoxaemia in shunting states
Pulmonary embolism causes increases V:Q ratio (increased
alveolus dead space)
Giving oxygen is more useful in a true shunt than in a shunt-like
state, e.g. atelectasis or lungs’ collapse
Inspiration occupies 70%, expiration 30% of a normal respiratory
cycle
Paradox is present when inspiratory time exceeds expiratory time
Respiratory paradox can be caused an obstruction in a large airway
Respiratory paradox is typically associated with pulsus paradoxus
Surfactant:
(a)
(b)
(c)
(d)
Is a glycoprotein
Is an important factor in preventing pulmonary oedema
Has both a rapid synthesis and turnover rate in the body
Is produced by the fetus around the 25-26th week
21
105.
Concerning the surface tension (ST)
(a)
(b)
(c)
(d)
106.
Airway resistance:
(a)
(b)
(c)
(d)
107.
(d)
Bronchoconstrictor vagal tone is greatest at night
Non-adrenergic non-cholineergic nerves are bronchodilator
The submucosal bronchial venous plexus extends almost to the
alveoli
The mucociliary escalatory is stimulated by the vagus nerve
Regarding the carriage of Oxygen (O2):
(a)
(b)
(c)
(d)
109.
Is a major factor in he elastic resistance of the lungs
Is mainly determined by the calibre of the airways
Falls at high altitude
Increases as lung volume increases
Within the bronchial tree:
(a)
(b)
(c)
108.
If the STs of two connecting bubbles are the same, then the smaller
bubble will empty into the larger one
The surface tension of a flat water layer is independent of the area
The surface tension of water, after adding detergent is dependent
on the area of the water/air interface
The surface tension of water, after adding lung extract, is
dependent on the area of the water/air interface
Normally the Pa O2 exceeds the Pa N2
One gram of Hb can combine with 2, 5ml O2
The Pa O2 is altered if the concentration of Hb is altered
The total pressure of gases is the same in arterial and venous
blood
Transpiration of oxygen in blood:
(a)
(b)
(c)
(d)
It is enhanced by an increase in the local P CO2
The saturation of arterial blood with O2 reaches 100% when
breathing pure O2 at sea level
The Pa O2 rises very considerably if one inhales pure O2 at sea
level
The Pa O2 is likely to be normal in polycythemia vera
22
110.
Regarding the CO2 in the blood:
(a)
(b)
(c)
(d)
111.
In the central control of breathing:
(a)
(b)
(c)
(d)
112.
(d)
Carotid and aortic bodies respond to a fall in plasma pH
Carotid bodies respond to a rise in local PCO2
Cells of the carotid and aortic bodies have a very high metabolic
rate
Aortic bodies respond to a fall in plasma pH
Concerning peripheral chemoreceptors:
(a)
(b)
(c)
(d)
114.
The cells of the central respiratory center are chemoreceptors
Inspiratory neurons fire even if isolated from accessory centers
Inspiratory neurons are mainly concentrated in the ventral part of
the medulla oblongata
The apheustic and pheumotoxic centers have opposing effects
The peripheral chemoreceptors:
(a)
(b)
(c)
113.
A low PO2 favours increased carriage of CO2 by Hb
About 10% of blood CO2 is carried in the form of carbamino
compounds
About 15% of blood CO2 is carried dissolved in plasma as H2CO3
Plasma CO2/O2 is the respiratory quotient of the subject
The carotid bodies are far more important than aortic ones in man
Stimulation of chemoreceptors causes bronchodilatation
Stimulation of chemoreceptors causes vasoconstriction in
pulmonary blood vessels
Chemoreceptors activity increases in acute haemorrhage
The peripheral chemoreceptors:
(a)
(b)
(c)
(d)
If stimulated, sometimes result in bradycardia
Have an insignificant role in the control of normal quiet breathing
Have an important role in the hyperventilation of moderate exercise
Have their ventilatory response to hypoxia dampened in acidosis
23
115.
Concerning the neural control of ventilation:
(a)
(b)
(c)
(d)
116.
Regarding lung reflexes:
(a)
(b)
(c)
(d)
117.
Is important in regular normal quiet breathing
Prolongs expiratory time
Receptors are located in the respiratory mucosa
Receptors are stimulated by the volume but not by the rate of gas
inspired
In hypoxia:
(a)
(b)
(c)
(d)
119.
The Hering-Breuer inflation reflex is sensitized if lung compliance
rises
The Hering-Breuer deflation reflex is sensed by same receptors as
the inflation reflex
–receptors are stimulated by both mechanical and chemical
stimuli
The cough reflex from larynx, thachea, main bronchi is only elicited
by mechanical stimuli
The Hering-Breuer inflation reflex:
(a)
(b)
(c)
(d)
118.
Local brain-stem activity is important in stimulating respiratory
neurons
Motoneurons to the diaphragm start from C1 – C2
Activity in the swallowing center inhibits the respiratory center
Ability of an infant to swallow and breath simultaneously is mainly
due to neural synchronization
The spinal cord is the most sensitive organ to hypoxaemic damage
The liver may be irreversibly damaged if blood supply is stopped for
3-4 minutes
Tissue hypoxia can occur in the absence of arterial hypoxaemia
Low oxygen tensions aggravated any ventilation/perfusion
mismatch
Consequences of hypoxia at altitude:
(a)
(b)
(c)
(d)
Cyanosis develops
The hypoxia directly dilates systemic blood vessels
There is usually a marked rise in arterial blood pressure
A rapid ascent to 2.5km is associated with acute mountain sickness
in untrained individuals
24
120
During acclimatization to high altitude:
(a)
(b)
(c)
(d)
Chronic hypoxaemia increases vascularity in most organs
Polycythemia begins within 4 – 6 weeks of exposure to high altitude
The sensitivity of the central chemoreceptor to CO2 is blunted
Hyperventilatin is abolished by breathing oxygen
25