Question 1
Which of the following options best describes these
arterial blood gas results pH 7.32, pCO2-31mmHg
and HCO3-20mmol/L?
Your answer was not correct
A Primary metabolic acidosis
B A picture consistent with diuretic abuse
C Mixed respiratory acidosis Your Answer
D Compensated metabolic acidosis Correct Answer
Explanation
The formula expressing the expected C02 level in a metabolic acidosis is;
- CO2=(1.5 x HCO3) +8
Therefore;
CO2= 30+8
CO2 =38
Question 2
In chronic acidosis, the major adaptive buffering
system in the urine is which of the following?
Your answer was not correct
A Carbamino compounds
B Bicarbonate Your Answer
C Ammonium Correct Answer
D Phosphate
Explanation
Ammonia (NH3) buffering occurs via the following reaction
NH3 + H = NH4
Ammonia is produced in the proximal tubule from glutamine which is an
amino acid, a reaction which is enhanced by an acid load and by
hypokalaemia. Ammonia (NH3) is converted to ammonium (NH4) by
intracellular H ions and is secreted into the proximal tubular lumen.
In the ascending limb of the loop of Henle, NH4 is transported into the
interstitium of the medulla where it dissociates back into NH3 and H ion.
The NH3 diffuses into the lumen of the collecting duct, where it is
available to buffer H ions, becoming NH4 which is trapped in the lumen
and excreted as the chloride salt. Every H ion buffered in this way
allows HCO3 to be returned to the systemic circulation.
Question 3
Which of the following options best describes the
changes found in uncompensated respiratory
alkalosis?
Your answer was correct
A Decreased pH, increased HCO3-, and normal PaCO2
B Increased pH, low HCO3-, and normal PaCO2
C Decreased pH and HCO3- and normal PaCO2
D Increased pH, normal HCO3-, and a low PaCO2 Correct
Answer
Explanation
A decline in PaCO2 will produce a respiratory alkalosis. This will increase the pH.
Uncompensated respiratory alkalosis means that the HCO3 has not had enough time to
be removed (lowered) to compensate for the loss of CO2
Question 4
In a patient with a plasma pH of 7.1, the HCO3/H2CO3 ratio is?
Your answer was correct
A 0.2
B 20
C 10 Correct Answer
D1
Explanation
pH HCO3/H2CO3 ratio is;
- 7.4=20
- 6.0=0.9
- 7.1=10
- 7.3=16
Question 5
Regarding buffers in the blood, which of the
following statements is correct?
Your answer was correct
A The carbonic acid-bicarbonate buffering system will
function without carbonic anhydrase Correct Answer
B The principle buffers in interstitial fluid is phosphate
C Haemaglobin has a lower buffering capacity than plasma
proteins
D Carbonic anhydrase is present in plasma
Explanation
HB is a major buffer in the blood. Hb has six times the buffering capacity of the plasma
proteins. This is due to the fact that Hb moleculae contains 38 histidine residues and is much
more abundant in the blood. Carbonic anydrase is not present in the plasma. It is found in the
red blood cells, gastric acid secreting cells and in renal tubular cells.The principle interstitial
buffer is the carbonic acid-bicarbonate system (CA-B). The CA-B system will function without
the carbonic anhydrase enzyme, but it will do so slowly
Question 6
Which of the following does not represent an acid
load to the body?
Your answer was correct
A Fruit Correct Answer
B Diabetic ketoacidosis (DKA)
C Chronic renal failure (CRF)
D Ingestion of acid salts
Explanation
An anion gap metabolic acidosis can be caused by: Methanol, metformin, uraemia, renal
failure, ketoacids, lactic acids, ethanol, salicylates, ethylene glycol, paraldehyde, toluene, iron
and cyanide.
Question 7
Which of the following statements is correct in
relation to the anion gap?
Your answer was not correct
A It is the difference between cations not including Na and
K and anions not including HCO3 Your Answer
B It consists mainly of HPO4, SO4 and organic acids
Correct Answer
C It is increased in hyperchloraemic acidosis due to
ingestion of NH4Cl
D It is decreased when albumin is increased
Explanation
The anion gap refers to the difference between the concentration of cations other than Na and
the concentration of anions other than Cl and HCO3 in the plasma. It is increased when the
plasma concentrations of K, Ca, Mg are decreased. When the concentration of proteins
increase so does the anion gap. It is decreased when cations are increased or when albumin is
decreased. Albumin is a negatively charged protein and its loss from the serum results in the
retension of other negatively charged ions like chloride and bicarbonate. As theses ions are
used to calculate the anion gap, there is a subsequesnt decrease in the anion gap. It is not
increased in hyperchloremic acidosis due to ingestion of NH4CL or carbonic anhydrase
inhibitors.
Question 8
Which of the following H+ concentration is
compatible with life?
Your answer was not correct
A 0.000000005 meq Your Answer
B 0.00000004 meq Correct Answer
C 0.00000001 meq
D 0.00000002 meq
Explanation
0.00000004 meq equals a pH of 7.4
0.00000001= 8
0.00000002= 7.69
0.000000005= 8.3
Question 9
Regarding the anion gap which of the following
causes a normal anion gap metabolic acidosis?
Your answer was correct
A Diarrhoea Correct Answer
B Uraemia
C Renal tubular acidosis type 3
D Rhabdomyolysis
Explanation
The anion gap refers to the difference between the concentration of
cations other than Na and the concentration of anions other than Cl and
HCO3 in the plasma. It is increased when the plasma concentrations of
K, Ca, Mg are decreased. When the concentration of proteins increase
so does the anion gap. It is decreased when cations are increased or
when albumin is decreased. Albumin is a negatively charged protein
and its loss from the serum results in the retension of other negatively
charged ions like chloride and bicarbonate. As theses ions are used to
calculate the anion gap, there is a subsequesnt decrease in the anion
gap. It is not increased in hyperchloremic acidosis due to ingestion of
NH4CL or carbonic anhydrase inhibitors.
Gastrointestinal loss of HCO3 due to diarrhoea, causes a normal anion
gap metablic acidosis. The HCO3 is lost and replaced by a chloride
anion. If vomiting were to occur, it would result in a hypochloraemic
alkalosis.
Note: Thre is only 3 types of RTA: type 1, 2, and 4 Uraemia and
rhabdomyolysis both cause a raised anion gap metabolic acidosis
Both Uraemia and rhabdomyolysis cause a raised anion gap metabolic
acidosis
Question 10
Regarding blood buffers, what is the
HCO3:H2CO3 ratio at a PH of 7.4?
Your answer was not correct
A 10 Your Answer
B 16
C1
D 20 Correct Answer
Explanation
The ration at pH- 7.4=20,
- 6.0=0.9
- 7.1=10
-
7.3=16
Question 11
What is the osmolality of the interstitium at the tip
of the papilla?
Your answer was not correct
A 200 Your Answer
B 800
C 1200 Correct Answer
D 2000
Explanation
Question 12
Where in the kidney is the tubular fluid isotonic
with the renal interstitium?
Your answer was not correct
A Collecting ducts Your Answer
B Proximal convoluted tubule (PCT) Correct Answer
C Distal convoluted tubule (DCT)
D Ascending limb of the Loop of Henle
Explanation
In the PCT, water moves passively out of the tubule along the osmotic
gradients set up by the active transport of solutes. This maintains
isotonicity. I also think that the tip of the descending loop of Henle,
where the water has moved out of the loop due to the hypertonicity of
the interstitium, this area will eventually become isotonic as the water
equlabrates on either side and the gradients set up by the solutes is
overcome.
Question 13
With regard to urea, which of the following
statements is correct?
Your answer was not correct
A It moves actively out of the proximal tubule Your Answer
B It plays no part in the establishment of an osmotic
gradient in the medullary pyramids
C There are 4 urea transporters in the kidney Correct
Answer
D A high protein diet reduces the ability of the kidney to
concentrate urine
Explanation
Urea moves via facilitated diffusion out of the (late) proximal tubule. It does play a role in the
establishment of an osmotic gradient in the medullary pyramids. It increases the ability of the
kidney to concentrate urine in the collecting ducts. A high protein diet increases the ability of
the kidneys to concentrate the urine. There are 4 urea transporters which mediate the
fascilitated diffusion. There is infact a 5th transporter but it is found in the testis
Question 14
Which of the following is the most permeable to
water?
Your answer was not correct
A Thick ascending limb of the loop of Henle Your Answer
B Distal convoluted tubule (DCT)
C Thin descending loop of Henle Correct Answer
D Cortical portion of collecting tubule
Explanation
Nephron’s permeability to water (0 to 4+)
- Thin descending LOH 4+
- Thin ascending LOH 0
- Thick ascending LOH 0
- DCT equivocal
- Cortical portion of the collecting tube 3+
- Outer medullary portion of the collecting tubule 3+
- Inner medullar portion of the collecting tubule 3+
Urea moves via facilitated diffusion out of the proximal tubule. It does
play a role in the establishment of an osmotic gradient. It increases the
ability of the kidney to concentrate urine
Question 15
Glucose reabsorption in the kidney is?
Your answer was not correct
A A passive process Your Answer
B Closely associated with potassium
C Occurs predominantly in the distal tubule
D Resembles glucose reabsorption in the intestine Correct
Answer
Explanation
Glucose reabsorption is an active process, it is closely associated with sodium and occurs
predominantly in the proximal convoluted tubule (PCT).
Question 16
Renal acid secretion is affected by all the following
with the exception of?
Your answer was correct
A Calcium Correct Answer
B PaCO2
C Carbonic anhydrase
D Aldosterone
Explanation
Renal acid secretion is altered by changes in the intracellular PCO2, K concentration,
carbonic anhydrase level and the adrenocorticol hormone concentration (including
aldosterone).
Question 17
With regard to osmotic diuresis, which of the
following statements is correct?
Your answer was not correct
A Urine flows are much less than in a water diuresis Your
Answer
B The concentration of the urine is less than plasma
C Increased urine flow is due to decreased water
reabsorption in the proximal tubule and loop of Henle Correct
Answer
D Osmotic diuresis can only be produced by sugars such
as mannitol
Explanation
In an osmotic diuresis, there is an increase in urine flow and the urine concentration
approaches that of plasma. There is maximal vasopressin release. Polysaccharides, NaCl and
urea can all produce an osmotic diuresis.
Question 18
Regarding the absorption of sodium in the proximal
tubule, which of the following options is correct?
Your answer was not correct
A Proximal tubule reabsorbs 80% of the filtered sodium
Your Answer
B Causes increasing hypertonicity
C Is powered by Na+/H+ ATPase
D Shares a common carrier with glucose Correct Answer
Explanation
Proximal convoluted tubule (PCT) reabsorbs 60% of filtered sodium. It is powered by the
Na/K-ATPase. It does share a common carrier with glucose but this is not the primary
mechanism of Na reabsorption which is the Na/H exchange.
Question 19
Which of the following is best for measuring
Glomerular filtration rate (GFR)?
Your answer was not correct
A Radiolabelled albumin Your Answer
B Inulin Correct Answer
C Deuterium oxide
D Tritium oxide
Explanation
The best substance to measure GFR is one that is freely filtered, is neither reabsorbed nor
secreted, is nontoxic and not metabolized by the body. Inulin, a polymer of fructose, with a
molecular weight of 5200 that is found in dahlia tubers, meets these criterias.
Question 20
The osmolality of the pyramidal papilla is?
Your answer was not correct
A 400 Your Answer
B 800
C 1200 Correct Answer
D 1600
Explanation
There is a graded increase in the osmolality of the interstitium of the pyramids, the
osmolality at the tips of the papillae normally being about 1200 mosm/kg of H2O,
approximately four times that of sodium.
Question 21
With a fall in systemic blood pressure, which of the
following options is correct?
Your answer was not correct
A Glomerular filtration rate (GFR) falls more than renal
plasma flow Your Answer
B There is efferent arteriolar constriction Correct Answer
C The filtration fraction falls
D Glomerular filtration rate (GFR) does not change
Explanation
During a fall in systemic blood pressure, renal plasma flow decreases more than the
glomerular filtration rate (GFR) and filtration fraction increases. Both afferent and efferent
arterioles are constricted but the efferents to a greater degree. Sodium retention is marked,
and the nitrogenous products of metabolism are retained in the blood giving rise to azotemia
and uremia. When hypotension is prolonged, renal tubular damage may be severe giving rise
to acute renal failure (ARF)
Question 22
Which of the following is true with regard to
bladder emptying?
Your answer was not correct
A The first urge to void is at 400 mls Your Answer
B Intravesical pressures can remain constant over a range
of volumes Correct Answer
C Voiding reflex is dependent on sympathetic control
D Parasympathetic reflex controls external urethral
sphincter
Explanation
Question 23
In the kidney, Na+ is most readily reabsorbed
with?
Your answer was not correct
A Glucose Your Answer
B K+
C Ca++
D Cl Correct Answer
Explanation
Question 24
The filtration fraction of the kidney is
approximately?
Your answer was not correct
A 0.1 Your Answer
B 0.2 Correct Answer
C 0.3
D 0.4
Explanation
Filtration fraction is 0.16-0.20
Question 25
With regard to renal autoregulation, which of the
following options is correct?
Your answer was not correct
A It has optimum autoregulation over an arterial blood
pressure range of 60 - 100 mmHg Your Answer
B Medullary blood flow is greater than cortical blood flow
C Prostaglandins increase medullary blood flow
D Prostaglandins increase cortical blood flow Correct
Answer
Explanation
The kidney has optimum autoregulation within an arterial blood pressure range of 90220mmHg. Cortical blood flow is greater than medullary although the cortex has less oxygen
extraction. Prostaglandins decrease medullary blood flow.
Question 26
Regarding the composition of normal urine, which
of the following is correct?
Your answer was correct
A No protein Correct Answer
B Constant SG of 1.010
C pH is acidic
D Urine output typically 500 mL/day
Explanation
Under normal circumstances there is neither glucose nor protein in the urine.
Normal reference ranges are:
SG 1.003-1.035,
ph is closer to 7.0,
urine output is typically 1-2L/day.
Question 27
In the kidney, Na is mostly reabsorbed with which
of the following?
Your answer was not correct
A HCO3 Your Answer
B glucose
C Cl Correct Answer
DK
Explanation
Question 28
Regarding permeability and transport in the
nephron, which of the following options is correct?
Your answer was not correct
A Thick portion of the ascending loop of Henle is
permeable to water Your Answer
B Thin portion of the ascending loop of Henle has largest
permeability for NaCl Correct Answer
C Thin descending loop of Henle is impermeable to water
D Collecting tubule is highly permeable to water
Explanation
The Loop of Henle:
The thin descending portion of the lopp of Henle is highly permeable to
H2O,
The thin ascending portion of the lopp of Henle is not permeable to H2O
The thick ascending portion of the lopp of Henle is not permeable to
H2O
The thin ascending portion of the lopp of Henle is highly permeable to
NACL.
The collecting tubules are only highly permeable to water in the
presence of vasopressin. Without it they are only slightly permeable
Question 29
Regarding the bladder, which of the following
statements is correct?
Your answer was not correct
A There is a relatively constant wall tension as volume
increases Your Answer
B There is an increasing pressure if volume increases
C Sympathetic nerves initiate micturiction
D Urge to void occurs arround 150 mls Correct Answer
Explanation
The tension in the bladder increases as the bladder fills but so does the radius, therefore the
increase is slight until the bladder is full (Laplace's law= 2T/R, where T is wall tesion and R is
the radius). Between 1-400mls there is only a slight increase in pressure to volume. Micturation
is activated by the parasympathetic nervous system. The bladder also has an inherent
contractile activity.
Question 31
Which of the following statements is correct in
relation to the anatomic dead space?
Your answer was not correct
A Varies with minute ventilation Your Answer
B Is typically 150 mls Correct Answer
C W ill increase in chronic obstructive pulmonary diesease
(COPD)
D Is alveolar minus the physiological dead space
Explanation
Anatomic dead space is the volume of the conducting airways. It is
normally 150ml, and it increases with large inspirations because of the
pull exerted on the bronchi by the lung parenchyma. It also changes
with the size and posture of the subject. It is measured by Fowler's
method.
Question 32
The Haldane effect refers to which of the following
options?
Your answer was correct
A The increased capacity for deoxygenated blood to carry
CO2 Correct Answer
B The carriage of O2 according to Henry's law
C The chloride shift that maintains electrical neutrality
D The dissociation constant for the bicarbonate buffer
system
Explanation
Henry’s law refers to the amount of dissolved oxygen, which is proportional to the pressure of
oxygen. At a constant temperature, the amount of a given gas dissolved in a given
type and volume of liquid is directly proportional to the partial pressure of that gas in
equilibrium with that liquid.The chloride shift which maintains electrical neutrality is the
Hamburger effect.
Question 33
Laplace's law (P=2T/r) explains which of the
following?
Your answer was not correct
A The observed elastic recoil of the chest Your Answer
B The tendency of small alveoli to collapse Correct
Answer
C The change in volume per unit change in pressure
D That pressure is inversely proportional to tension
Explanation
If the surface tension is not kept low when the alveoli become smaller during expiration,
they collapse in accordance with the law of Laplace. The reduction in surface tension is
achieved by surfactant. Law= the tension in the wall of a cylinder (T) is equal to the
product of the transmural pressure (P) and the radius (r) divided by the wall thickness
(w). Consequently, the smaller the radius of the alveoli, the lower the tension in the wall
is necessary to balance the distending pressure
Question 34
In control of ventilation, the medullary
chemoreceptors respond to changes by which of the
following?
Your answer was not correct
A O2 tension Your Answer
B CO2 tension
C H+ concentration Correct Answer
D HCO3 concentration
Explanation
The central chemoreceptors are surrounded by brain extracellular fluid and respond to
the changes in H+ concentration. An increase in H+ concentration stimulates ventilation
and a decrease inhibits it. Although the BBB is relatively impermeable to H+ and HCO3ions, CO2 molecule diffuses easily across it. When the blood PCO2 rises, CO2 diffuses
into the CSF from the cerebral blood vessels liberating H+ ions that STIMULATE the
chemoreceptors.
Question 35
Compliance of the lung is reduced by all the
following with the exception of?
Your answer was not correct
A Fibrosis Your Answer
B Consolidation
C Emphysema Correct Answer
D Alveolar oedema
Explanation
Compliance is also increased in the normal ageing lung
Question 36
What is the maximum volume left in the lung after
maximal forced expiration?
Your answer was not correct
A 0.5 Litres Your Answer
B 3 Litres
C 2 Litres
D 1Litre Correct Answer
Explanation
The volume expelled by an active expiratory effort after passive expiration is the
expiratory reserve volume, and the air left in the lungs after a maximal expiratory effort
is the residual volume. Men=1.2 and women=1.1 litres
Question 37
When walking at a steady pace the increase in
respiratory rate is due to?
Your answer was not correct
A Decreased PO2 Your Answer
B Increased CO2
C Increased pH
D None of the above Correct Answer
Explanation
The pH, PCO2 and P02 remain constant during moderate exercise. An abrupt rise in
ventilation at the start of exercise is due to psychic stimuli and afferent impulses from the joints,
muscles and tendons. The gradual increase is humoral even though PCO2, PO2 and pH
remain constant in moderate exercise. The increase in ventilation is proportionate to the
increase in O2 consumption but the mechanism responsible for stimulation is still the subject of
much debate.
Question 38
What is the PO2 of alveolar air with a CO2 of 64
and a respiratory quotient (RQ) of 0.8?
Your answer was not correct
A 35 Your Answer
B 52
C 69 Correct Answer
D 72
Explanation
Alveolar gas equation PAO2= (atmospheric pressure – vapour pressure) X inspired oxygen
percentage - PaCO2/0.8
Therefore;
PAO2= (760-47) X 0.21 – 64/0.8 which equals 69 mmHg
Question 39
A permanent inhabitant at 4,500 feet has adapted
by which of the following mechanisms?
Your answer was not correct
A A high alveolar PO2 Your Answer
B A decreased 2,3, diphosphoglycerate (DPG)
C Increased ventilation Correct Answer
D A normal HCO3-
Explanation
A permanent inhabitant at 4,500 feet will have a lower alveolar PO2 relative to sea level. By
hyperventilating, he can increase his O2. He will have an increased 2,3 diphosphoglycerate
(DPG). He must also increase ventilation, as this is the most important feature in
acclimatization. He will have a low arterial HCO3, which the body creates by renally excreting
the bicarbonate allowing the patient to hyperventilate.
Question 40
With regard to pulmonary gas exchange, which of
the following statements is correct?
Your answer was correct
A Transfer of nitrous oxide is perfusion limited Correct
Answer
B Diffusion is inversely proportional to the partial pressure
gradient
C The diffusion rate for CO2 is double that of O2
D Transfer of O2 is diffusion limited
Explanation
Diffusion is proportional to the partial pressure gradient. The diffusion rate for CO2 is twenty
times faster than O2. The transfer of O2 is perfusion limited.
According to West's Resp Physiology, the amount of nitrous oxide
taken up by the blood depends entirely on he amount of available blood
flow and not on the diffusion properties of the blood gas barrier. The
transfer of nitrous oxideis therefore perfusion limited.
Question 41
With regard to the distribution of pulmonary blood
flow, which of the following options is correct?
Your answer was not correct
A Typically, there is a zone at the apex which is not
perfused Your Answer
B The mean pulmonary arterial pressure is 8 mmHg
C Hypoxia leads to pulmonary dilation
D In some areas, flow is determined by the arterial/alveolar
pressure difference Correct Answer
Explanation
Only in diseased lungs is there an area which is not perfused. The mean pulmonary arterial
pressure is 15mmHg. Hypoxia leads to pulmonary constriction.
Question 42
Permanent high altitude is associated with all of the
following changes except?
Your answer was correct
A Increased arterial blood HCO3 Correct Answer
B Increased pulmonary artery pressure
C Increased alveolar ventilation
D A normal PaCO2
Explanation
Permanent high altitude states result in the kidneys decreasing HCO3 so that hyperventilation
can compensate. This is the most important feature of acclimatization to high altitude. The
mechanism of hypervetilation is hypoxic stimulation of the peripheral chemoreceptors. The
resulting low arterial PCO2 and alkalosis tends to inhibit this increase in ventilation. After 2-3
days the arterial blood pH is returned to normal by the renal excretion of HCO3. The brakes on
ventilation are thus reduced and respiration may increase further. Arterial 2,3
diphosphoglycerate (DPG) also increases.
Physiology - All
Question 43
Residual volume in a 70kg man most closely
approximates which of the following values?
Your answer was correct
A 1.0 litre Correct Answer
B 2.0 litre
C 3.0 litre
D 4.0 litre
Explanation
Residual volume is approximately 1.2L
Question 44
Given that the intrathoracic pressure changes from
5 cmH2O to 10 cmH2O with inspiration and a tidal
volume (TV) of 500 mls, what is the compliance of
the lung?
Your answer was not correct
A 100 L/cmH2O Your Answer
B 0.1 L/cmH2O Correct Answer
C 1 L/cmH2O
D 10 L/cmH2O
Explanation
Compliance is the volume change per pressure change.
C=V/P
C=L/cmH2O
Therefore;
C=0.5/5 which equals 0.1
Question 45
In walking, which of the following causes an
increased respiratory rate?
Your answer was not correct
A Decreased PO2 Your Answer
B Increased PCO2
C Decreased pH
D None of the above Correct Answer
Explanation
The pH, PCO2 and P02 remain constant during moderate exercise. An abrupt rise in
ventilation at the start of exercise is due to psychic stimuli and afferent impulses from the joints,
muscles and tendons. The gradual increase is humoral even though PCO2, PO2 and pH
remain constant in moderate exercise. The increase in ventilation is proportionate to the
increase in O2 consumption but the mechanism responsible for stimulation is still the subject of
much debate.
Question 46
If compliance of the lung is 30mL/cmH20 and the
average tidal volume is 600mL, the pressure
change per breath is?
Your answer was correct
A 20 cm H20 Correct Answer
B 10 cm H20
C 12 cm H20
D 18 cm H20
Explanation
Compliance is the volume changes per pressure change. C=V/P, therefore P=V/C, P=600/30
which is equal to 20 cm H20
Question 47
What is the oxygen pressure in the bronchi at an
altitude where barometric pressure is 500 mmHg,
breathing 30% O2?
Your answer was correct
A 135 mm Hg Correct Answer
B 8 5 m m Hg
C 129 mm Hg
D 105 mm Hg
Explanation
Alveolar gas equation
PAO2= oxygen percentage(atmospheric pressure-47)- (pCO2 [arterial
pressure of cardon dioxide]/0.8)
PAO2=0.3(500-47) is equal to 135.9mmHg
Note: Because the question said bronchi, the amount of CO2 is very
little. In inspiration CO2 levels at your mouth and main bronchi are
negligable. As you go down the bonchial tree into the alveoli, CO2 starts
to make up a concentration. Therefore if the question asks for the
pressure in the alveoli, you will need the CO2 pressure (to complete
the alveolar gas equation). In this case, because it is in the bronchi the
CO2 can be ignored.
Question 48
Regarding the Respiratory Quotient (RQ), which of
the following options is correct?
Your answer was not correct
A RQ fat = 0.95 Your Answer
B RQ Carbohydrates= 0.95
C RQ brain > 0.95 Correct Answer
D RQ liver > 0.95
Explanation
The RQ of
- Fat is 0.7
- Carbohydrates is 1.00
- Brain is 0.97-0.99
Question 49
With regard to lung compliance, which of the
following statements is correct?
Your answer was correct
A It changes in inspiration compared with expiration
Correct Answer
B It is independent of lung volume
C It decreases with age
D It decreases with emphysema
Explanation
Compliance is slightly greater when measured during deflation then when measured during
inflation. Compliance increases with age and emphysema and is decreased in pulmonary
congestion and interstitial pulmonary fibrosis. Compliance of a human lung is approximately
200ml/cm water.
Question 50
Which of the following statements is true in
relation to airway resistance?
Your answer was correct
A It increases with forced expiration Correct Answer
B It is independent of lung volumes
C It is equal in inspiration and expiration
D It decreases while breathing through the nose
Explanation
Airway resistance will rise as the lung volume decreases. Airway resistance is not equal in both
expiration and inspiration and airway resistance will increase with nasal breathing (decreasing
the size of the tube increases the resistance 16 fold).
Question 51
Regarding ventilation, which of the following
options is correct?
Your answer was not correct
A Anatomical dead space is 1ml/kg Your Answer
B Lung units with a high Ventilation/perfusion (VQ) quotient
have decreased alveolar minute ventilation Correct Answer
C Increased respiratory rate (RR) decreases anatomical
dead space
D At the end of inspiration, the chest wall recoils and pulls
lungs back to original position
Explanation
Anatomical dead space is 2ml/kg (150ml). An increased respiratory rate will increase the
volume of the dead space. Dead space also depends on the size and posture of the patient. At
the end of inspiration, the lung recoil begins to pull the chest back to the expiratory position,
where the recoil pressures of the lung and chest balance. The pressure in the airways
becomes slightly positive and the air flows out. Expiration during quiet breathing is passive in
the sense that no muscles, which would tend to decrease intrathoracic volume, contract.
Lung units with high V/Q ratios occur at the top of the lung and low V/Q ratios occurs at the
bottom of the lung
The lungs ventilate better at the base because of the better blood flow. (even though the PO2
at the apex 132 and base 89)
The reason for the high V/Q ratio at the top is because the blood flow or Q (denominator) is
much lower therefore a better V or numerator
At the base the V is lower and the Q is better. Therefore a lower V/Q ratio.
MV= volume of air inhaled or exhaled in one minute
While the increase in ventilation to a lung with V/Q inequality is usually effectiveat reducing
PCO2, it is much less efffective at increasing PO2. This is due to the different dissociation
curves. O2's curve is very flat at the top which means that only UNITS with moderately low V/Q
ratios will benefit from increased ventilation. The CO2 curve is almost straight at physiological
levels, therefore an increase in ventilation will raise the output of the lung UNITS with both high
and low V/Q ratios
Therefore high V/Q areas will have low MV and low V/Q areas will have high MV
Question 52
Regarding the lungs, which of the following
statements is correct?
Your answer was not correct
A Ventilation is greatest in middle zone Your Answer
B Perfusion is greatest at the base Correct Answer
C Ventilation/perfusion (VQ) quotient is directly proportional
to gas exchange
D Ventilation/perfusion (VQ) quotient is inversely
proportional to gas exchange
Explanation
Ventilation is greatest in the upper zones of the lungs. Ventilation perfusion (VQ) will affect gas
exchange in different ways: A high VQ means more ventilation and less blood flow and the
arterial blood PO2 will approach that of inspired air. With a low VQ, the arterial PO2 will
approach that of mixed venous blood.
Question 53
What percentage of the blood is contained within
the venous system
Your answer was not correct
A 40 Your Answer
B 55 Correct Answer
C 65
D 70
Explanation
Capillaries contain 5% and the arterial system contains 11%
Question 54
The systemic circulation peripherally has which of
the following?
Your answer was not correct
A Decreased red cell size Your Answer
B Decreased pH Correct Answer
C Increased chloride
D Decreased HCO3-
Explanation
Question 55
Isovolumetric contraction of the ventricle is
associated with which of the following?
Your answer was correct
A Decreasing aortic pressure Correct Answer
B Aortic back flow
C Open mitral and tricuspid valves
D Open aortic and pulmonary valves
Explanation
The period of isovolumetric ventricular contraction lasts about 0.05s
until the pressures in the left and right ventricles exceed the pressures
in the aorta and pulmonary artery and the aortic and pulmonary valves
open. During this phase the atrioventricular (AV) valves bulge into the
atria causing a small but sharp rise in the atrial pressure. There is an
associated decrease in intra aortic pressure because blood is flowing
from the arteries into the peripheral vascular beds and no blood is being
ejected form the heart. During this stage the mitral and tricuspid valve
close. The aortic and pulmonary valves are already closed
Question 56
Which of the following organs receives the largest
amount of the blood per kg of tissue?
Your answer was not correct
A Liver Your Answer
B Heart
C Kidney Correct Answer
D Brain
Explanation
Mass and blood flow ml/min
- Heart 0.3kg + 250ml/min,
- Kidney 0.3kg + 1260ml/min,
- Brain 1,4kg +750ml/min,
- Liver 2.6kg +1500ml/min
Question 57
The greatest percentage of the circulating volume is
contained within which of the following?
Your answer was not correct
A Capillaries Your Answer
B Large arteries
C Pulmonary circulation
D Venules and veins Correct Answer
Explanation
Capillaries=4500cm2, venule=4000cm2, arteriole=400cm2,
artery=20cm2, vein=40cm2, vena cava=18cm2.
Veins and venules contain 54% of circulating blood volume.
Capillaries contain 5% and the arterial system contains 11%
Question 58
The Poiseuille-Hagen formula shows that?
Your answer was not correct
A Longer tubes can sustain higher flow rates Your Answer
B Flow is directly proportional to resistance
C Flow will be doubled by a 20 % increase in vessel
diameter Correct Answer
D Turbulent flow is common in high velocity vessels
Explanation
Since flow varies directly and resistance inversely with the fourth power of the radius, blood
flow and resistance in vivo are markedly affected by small changes in the caliber of the
vessels. Thus flow through a vessel is doubled by an increase of only 19% in its radius; and
when the radius is doubled, resistance is reduced to 6% of its previous value. This is why
organ blood flow is so effectively regulated by small changes in the caliber of the arterioles and
why variations in arteriolar diameter have such a pronounced effect on systemic arterial
pressure.
Question 59
The 'c' wave of the jugular pulse is due to?
Your answer was not correct
A Atrial contraction against a closed tricuspid valve in
complete block Your Answer
B The increase in intrathoracic pressure during expiration
C Transmitted pressure due to tricuspid bulging in
isovolumetric contraction Correct Answer
D The rise in pressure before the tricuspid valve opens in
diastole
Explanation
The “a” wave is due to atrial systole. In addition, venous inflow stops, and the resultant rise in
venous pressure contributes to the “a” wave. The “c” wave is a transmitted manifestation of the
rise in atrial pressure produced by the bulging of the tricuspid valve into the atria during
isovolumetric ventricular contraction. The “v” wave mirrors the rise in atrial pressure before the
tricuspid wave opens during diastole
Question 60
All of the following contribute to venous blood
flow except?
Your answer was correct
A Oncotic pressure gradient Correct Answer
B Skeletal muscle contraction
C The pumping of the heart
D Intrathoracic pressure variations
Explanation
Blood flows through the blood vessels, including the veins, primarily because of the pumping
action of the heart. However, venous flow is aided by the heartbeat, the increase in negative
intrathoracic pressure during each inspiration, and contractions of skeletal muscle that
compress the veins (muscle pump)
Question 61
Which of the following is correct in relation to
endothelium derived relaxing factor (EDRF)?
Your answer was correct
A Shares a similar mechanism of action to glycerol trinitrate
(GTN) Correct Answer
B Activates adenyl cyclase
C Is the common pathway in the action of adenosine and
histamine
D Antagonises the action of thromboxane
Explanation
Endothelium derived relaxing factor (EDRF) is also known as nitric oxide (NO), and is
synthesized from argenine. It activates soluble guanylate cyclase, producing cyclic guanosine
monophosphate (cGMP), which in turn mediates the relaxation of vascular smooth muscle. NO
is inactivated by Hb. Adenosine, histamine and atrial natriuretic peptide (ANP) produce
relaxation of the vascular smooth muscle that is independent of the endothelium. Nitorglycerin
and other nitrovasodilators act in the same manner by stimulating guanylate cyclase in the
same manner as NO. Prostacyclin is more involved with thromboxane; the balance between
the two fosters localized platelet aggregation and consequent clot formation while preventing
excessive extension of the clot and maintaining blood flow around it.
Question 62
Regarding lymph, which of the following
statements is correct?
Your answer was not correct
A It has an increased protein content compared with
plasma Your Answer
B It has differing protein content in different areas Correct
Answer
C Fats cannot enter lymph
D It contains no clotting factors
Explanation
Lymph has a lower protein count of 7g/dl when compared to plasma.
Fats can enter the lymph system and it does contain clotting factors.
The greatest protein content in the lymph system occurs in the liver
followed by the heart and than the gastrointestinal tract (GIT). The
choroid plexus and the ciliary body components of the lymph system
contain no proteins
Question 63
The part of the cardiovascular system (CVS) with
the largest total cross-sectional area is the?
Your answer was not correct
A Arteries Your Answer
B large veins
C Capillaries Correct Answer
D Arterioles
Explanation
- Capillaries=4500cm2,
- Venules=4000cm2,
-
Arterioles=400cm2
Question 64
Flow through a narrow tube is proportional to?
Your answer was not correct
A Viscosity Your Answer
B Length
C Average pressure in the tube
D Pressure gradient Correct Answer
Explanation
Poiseuille-Hagen Formula states that the relation between the flow in a long narrow
tube, the viscosity of the fluid, and the radius of the tube is expressed mathematically in
this equation. The flow is proportional to the pressure difference between the two ends
of the tube and inversely proportional to the viscosity and length
Question 65
If a tubes diameter is increased from 1 to 2 cm?
Your answer was correct
A Resistance is decreased 16x Correct Answer
B Flow is doubled
C Flow is halved
D Resistance is increased 16x
Explanation
Poiseuille-Hagen Formula:
P= pressure difference between two ends of the tube n=viscosity r=
radius of the tube L=length of the tube F=flow
Flow= (Pa-Pb) X 8 X 1 X X L X r4 8 X n X L
Note that a change in radius alters resistance to the 4th power,
therefore a 2 fold increase in radius decreases resistance by a factor of
16
Question 66
Flow is?
Your answer was not correct
A Proportionate to mean pressure in tube Your Answer
B Proportionate to viscosity
C Proportionate to length
D Proportionate to pressure difference at 2 ends of a tube
Correct Answer
Explanation
Poiseuille-Hagen Formula:
P= pressure difference between two ends of the tube n=viscosity r=
radius of the tube L=length of the tube F=flow
Flow= (Pa-Pb) X 8 X 1 X X L X r4 8 X n X L
Note that a change in radius alters resistance to the 4th power,
therefore a 2 fold increase in radius decreases resistance by a factor of
16
Question 67
Which organ receives a blood flow of
approximately 250ml/min?
Your answer was correct
A Heart Correct Answer
B Liver
C Kidney
D Skin
Explanation
- Heart=250ml/min,
- Liver=1500ml/min,
- Kidneys=1260ml/min,
- Brain 750ml/min,
- Skin=460ml/min,
-
Skeletal muscle=840ml/min
Question 68
The proportion of cardiac output that goes to the
kidneys is?
Your answer was not correct
A 35% Your Answer
B 10%
C 15%
D 25% Correct Answer
Explanation
Approximate proportion of cardiac output;
- Liver=30%,
- Kidneys=25%,
- Brain=15%,
- Skin=10%,
- Heart muscle=5%,
-
Skeletal muscle 15%
Question 69
Regarding the T wave of the ECG, which is
correct?
Your answer was correct
A It represents ventricular repolarization Correct Answer
B An inverted T wave is always pathological
C It is caused by potassium infflux
D It refers to the absolute refractory period
Explanation
The T wave on the ECG refers to ventricular repolarisation. The interval
from the beginning of the QRS complex to the apex of the T wave is
referred to as the absolute refractory period. The last half of the T wave
is referred to as the relative refractory period. An inverted T wave can
be normal ina number of leads especially AvR and lead one. It is due to
the efflux of K through multiple type of K channels.
Question 70
The most rapid conduction of electrical impulses
occur in which of the following?
Your answer was not correct
A Atrioventricular (AV) node Your Answer
B Atrial pathways
C Bundle of His
D Purkinje system Correct Answer
Explanation
- AV node= 0.05ms (metres/second)
- SA node=0.5ms,
- Purkinje System=4ms,
- Atrial pathways=1ms,
- Ventricular muscles= 1ms,
- Bundle of His=1ms
The conduction system within the heart is very important because it
permits a rapid and organized depolarization of ventricular myocytes
that is necessary for the efficient generation of pressure during systole.
The time (in seconds) to activate the different regions of the heart are
shown in the figure to the right. Atrial activation is complete within about
0.09 sec (90 msec) following SA nodal firing. After a delay at the AV
node, the septum becomes activated (0.16 sec). All the ventricular
mass is activated by about 0.23 sec.
Question 71
With regard to cardiac action potentials, which of
the following options is correct?
Your answer was not correct
A Cholinergic stimulation increases the slope of the prepotential Your Answer
B The resting membrane potential decreases by vagal
stimulation
C Phase 0 and phase 1 are steepest in the AV node
D The action potential in the AV node is largely due to
calcium fluxes Correct Answer
Explanation
Cholinergic and vagal stimulation both decrease the peripotentials as
the nodal tissue membranes become hyperpolarized or more negative.
There are no phases to the cardiac pacemaker's action potential (unlike
the ventricular muscle). The action potentials in the SA and the AV
nodes are largely due to Ca with no contribution of Na influx.
The opening and closing of ion channels can induce a departure from
the resting potential. This is called a depolarisation if the interior
voltage becomes more positive (say from –70 mV to –60 mV), or
hyperpolarisation if the interior voltage becomes more negative (say
from –70 mV to –80 mV).
Therefore vagal stimulation causes the cell RMP to become
hyperpolarised- greater. The value goes form -90MV to say -130MV. the
negative just reflects the inside of the cell.
Question 72
Which of the following statements is correct with
regard to the 12 lead ECG?
Your answer was correct
A The standard limb leads record the potential difference
between 2 limbs Correct Answer
B Lead 11 is at 90 degrees for vector analysis
C V2 is placed in the 3rd left intercostal space
D +130 degrees is within the normal range for the axis
Explanation
Regarding the 12 lead ECG; V2 is placed in the 4th intercostal space. 30 to 110 degrees is considered a normal axis. Lead II lies at 60
degrees for vector analysis. The limb leads form the points of an
equilateral triangle and heart lies in the centre
Question 73
With regard to the cardiac cycle, which of the
following options is correct?
Your answer was correct
A Phase 1 represents atrial systole Correct Answer
B The aortic valve opens at the beginning of phase 2
C The T wave of the ECG occurs during phase 4
D The c wave is due to tricuspid valve opening
Explanation
The aortic valve opens at the end of stage 2. The T wave of the ECG
occurs during phase 3 (ventricular ejection). The c wave is the
transmitted manifestation of the rise in atrial pressure produced by the
bulging of the tricuspid wave into the atria during isovolumetric
ventricular contraction
Question 74
Cardiac output is decreased by which of the
following?
Your answer was correct
A Sitting from a lying position Correct Answer
B Pregnancy in the first trimester
C Exercise
D Sleep
Explanation
CO is decreased by: sitting or standing form a lying position, rapid arrhythmias and
heart disease.
It is increased by: anxiety and excitemnt, eating, exercise, high environmental
tempretures, pregnancy and adrenaline.
No change: sleep, moderate changes in environmental temperature
Question 75
Myocardial contractility is decreased by all of the
following except?
Your answer was not correct
A Barbituates Your Answer
B Hypercarbia
C Bradycardia
D Glucagon Correct Answer
Explanation
Glucagon, which increases the formation of cyclic adenosine
monophosphate (cAMP), is positively inotropic, and is recommended in
the treatment of some heart diseases. Theophylline and digitalis also
have an inotropic effect
Question 76
Under basal conditions the percentage of the heart's
caloric needs which is met by fat is?
Your answer was not correct
A 40% Your Answer
B 70%
C 60% Correct Answer
D 50%
Explanation
Under basal conditions, 35% of the caloric needs of the human heart
are supplied by carbohydrates, 5% by ketones and amino acids, and
60% by fats.
Question 77
During exercise in a fit, healthy young male, which
of the following options is correct?
Your answer was correct
A Stroke volume increases less than 200% Correct
Answer
B Stroke volume increases more than 300%
C Stroke volume increases more than 400%
D Stroke volume increases more than 700%
Explanation
Normal stroke volume (SV) is 70-90mls. A fit person can increase his
SV to a max of 126ml, which is, less than a 200% increase. Any further
increases in exercise will result in a decrease in SV due to a rising heart
rate and thus a shortening of diastole
Question 78
Cardiac output is changed as listed in all of the
following circumstances except?
Your answer was not correct
A Increased during exercise Your Answer
B Increased on eating
C Decreased by sleep Correct Answer
D Decreases when moving from a lying to a sitting position
Explanation
There is no change to cardiac output during sleep or moderate changes
in environmental temperature.
Decrease in cardiac output occurs during rapid arrhythmias, heart
disease and when sitting or standing from a lying position.
Increase in cardiac output occurs during anxiety and excitement, eating,
exercise, high environmental temperatures, pregnancy and adrenaline
Question 79
The cardiac output during exercise can increase by?
Your answer was not correct
A 200% Your Answer
B 500%
C 700% Correct Answer
D 600%
Explanation
Further, eating increases CO 30% and anxiety by 50-100%
Question 80
In the fasting state, which of the following meets
most of the hearts basic caloric requirements?
Your answer was correct
A Free fatty acids Correct Answer
B Glucose
C Lactate
D Protein
Explanation
Under basal conditions, 35% of the caloric needs of the human heart
are supplied by carbohydrates, 5% by ketones and amino acids, and
60% by fats. Following large ingestion of glucose, more pyruvate and
lactate is used. During prolonged starvation, more fat is used
Question 81
Regarding cardiac muscle, which of the following
statements is correct?
Your answer was not correct
A It can display tetanus Your Answer
B Calcium release from sarcoplasmic reticulum initiates
contraction Correct Answer
C The relative refractory period (RRP) is longer than the
absolute refractory period (ARP)
D Time of contraction is less than action potential
Explanation
The role of calcium in the excitation-contraction coupling is similar to its
role is skeletal muscle. However, it is the influx of extracellular calcium
that is triggered by activation of the dihydropyroidine channels in the T
system, rather than depolarization per se, that triggers release of stored
calcium from the sarcoplasmic reticulum. The absolute refractory period
(ARP) is longer than the relative refractory period (RRP). The time of
contraction is about 1.5 times longer. The cardiac muscle can never
display tetanus
Question 82
During strenuous exercise, a fit 20 yr male can
increase his stroke volume by?
Your answer was correct
A < 200% Correct Answer
B 300%
C 500%
D 400%
Explanation
Normal stroke volume (SV) is 70-90mls. A fit person can increase his
SV to a max of 126ml, which is, less than a 200% increase. Any further
increases in exercise will result in a decrease in SV due to a rising heart
rate and thus a shortening of diastole
Question 83
The slowest conducting cardiac tissue is?
Your answer was correct
A Atrioventricular (AV) node Correct Answer
B Atrial Pathways
C Ventricular muscle
D Bundle of His
Explanation
- AV node= 0.05ms (meters per second)
- SA node=0.5ms
- Purkinje System=4ms
- Atrial pathways=1ms
- Ventricular muscles= 1ms
- Bundle of His=1ms
The conduction system within the heart is very important because it
permits a rapid and organized depolarization of ventricular myocytes
that is necessary for the efficient generation of pressure during systole.
The time (in seconds) to activate the different regions of the heart are
shown in the figure to the right. Atrial activation is complete within about
0.09 sec (90 msec) following SA nodal firing. After a delay at the AV
node, the septum becomes activated (0.16 sec). All the ventricular
mass is activated by about 0.23 sec.
Question 84
Regarding the cardiac action potential, which of the
following statements is correct?
Your answer was not correct
A Unlike the nerve action potential there is no overshoot
Your Answer
B The plateau phase is based on K+ efflux
C The plateau phase can be up to 100 x longer than
depolarisation Correct Answer
D The relative refractory period prevents tetanus
Explanation
There is an overshoot in cardiac action potential and there is a plateau
phase (unlike in nerve action potential) before a return to the baseline.
The plateau phase is due to calcium influx. Cardiac depolarization lasts
about 2ms, but the plateau phase and repolarization lasts 200ms or
more. The absolute refractory period (phases 0-2 and half of three)
prevents tetanus
Question 85
In a man with congestive heart failure, which of the
following occurs?
Your answer was correct
A Increased renin production Correct Answer
B Increased albumin
C Increased atrial pressure
D Decreased angiotensin II production
Explanation
Incomplete atrial filling results in the activation of the sympathetic
nervous system and the angiotensin renin system
Question 86
In a healthy male who is running, which of the
following statements is correct?
Your answer was correct
A Systolic BP rises and diastolic BP either falls or stays the
same Correct Answer
B O2 extraction can increase 600%
C Maximal heart rate is independent of age
D Cardiac output can increase 1500%
Explanation
Heart muscle blood flow is 9ml/100g/min. The O2 extraction can
increase by 100%. Cardiac output can increase by 700% and there is a
net fall in peripheral resistance, due to a rise in systolic BP and a fall in
diastolic BP. Eating increases CO 30%, anxiety by 50-100%, and sitting
or standing from a lying position by 20-30%
Question 87
Fasting energy for the heart comes from?
Your answer was not correct
A Glycerol Your Answer
B Amino acids
C Glucose
D Free fatty acids (FFA) Correct Answer
Explanation
Under basal conditions, 35% of the caloric needs of the human heart
are supplied by carbohydrates, 5% by ketones and amino acids, and
60% by fats. Following large ingestion of glucose, more pyruvate and
lactate is used. During prolonged starvation, more fat is used
Question 88
The R wave on an ECG corresponds to which of
the following?
Your answer was correct
A Na influx Correct Answer
B Ca influx
C Ca efflux
D Na efflux
Explanation
The R wave is due to the initial depolarization of the cardiac muscle due
to the sudden influx of Na+ through the rapidly opening Na+ Channels
Question 89
Regarding ECGs, which of the following
statements is false?
Your answer was not correct
A ST represents ventricular repolarisation Your Answer
B PR interval represents atrial depolarisation and
conduction through the SA node Correct Answer
C QRS represents ventricular depolarisation and atrial
repolarization
D QT interval represents ventricular depolarisation and
ventricular repolarisation
Explanation
PR interval represents atrial depolarization and conduction through the
AV node
Note: In Ganong edition 22: the ST interval (QT minus QRS) reflects
ventricular repolarisation. In Ganong 23: ST interval (QT minus QRS)
reflects ventricular repolarisation (during T wave). the actual ST interval
is the time at which the entire ventricle is depolarized and roughly
corresponds to the plateau phase of the ventricular action potential.
Question 90
Regarding the isovolumetric contraction phase of
the cardiac cycle, which of the following
statements is correct?
Your answer was not correct
A The aortic valve is open Your Answer
B It is associated with decreasing intra-aortic pressure
Correct Answer
C The mitral valve is open
D Backflow into the aorta occurs
Explanation
The period of isovolumetric ventricular contraction lasts about 0.05s
until the pressures in the left and right ventricles exceed the pressures
in the aorta and pulmonary artery and the aortic and pulmonary valves
open. During this phase the atrioventricular (AV) valves bulge into the
atria causing a small but sharp rise in the atrial pressure. There is an
associated decrease in intra aortic pressure because blood is flowing
from the arteries into the peripheral vascular beds and no blood is being
ejected form the heart.
Question 91
The haemoglobin dissociation curve moves to the
left under which of the following circumstances?
Your answer was not correct
A Increased H+ concentration Your Answer
B Hypothermia Correct Answer
C Increased 2,3 diphosphoglycerate (DPG)
D Hypercarbia
Explanation
A drop in temperature, an increase in the pH (alkalosis), a decrease in 2,3 DPG and a
decreasing pCO2 all shift he haemoglobin dissociation curve to the left. Conversely, the
opposite would shift it to the right
Question 92
The principle mechanism for transporting CO2 in
the blood is which of the following?
Your answer was correct
A Bicarbonate Correct Answer
B Carboamino groups
C Dissolved in blood by Henry's law
D Haemoglobin
Explanation
Of approximately 49ml of CO2 in each decilitre of arterial blood, 2.6ml is
dissolved, 2.6ml is in carbamino compounds and 43.8ml is in HCO3
Question 93
Regarding granulocytes, which of the following
statements is correct?
Your answer was correct
A All have cytoplasmic granules Correct Answer
B Basophils are identical to mast cells
C Eosinophils phagocytose viruses
D Neutrophils have a half life of 4 days
Explanation
Basophiles only resemble mast cells and are not identical. Eosinphiles
phagocytose parasites. The half life of neutrophiles is 6 days.
Question 94
2,3 diphosphoglycerate (DPG) levels increase in all
of the following circumstances except?
Your answer was not correct
A Chronic hypoxia Your Answer
B Androgens
C Acidosis Correct Answer
D Congestive heart failure
Explanation
Thyroid hormone, growth hormone and androgens all increase the
concentration. Acidosis inhibits red cell glycolysis and causes the levels
to fall. Red cell 2,3 DPG concentration is increased in anaemia and in a
variety of diseases where there is chronic hypoxia. Ascent to high
altitudes also triggers a rise. Exercise has been reported to increase the
levels within 60 min. Stored blood has lower levesl of 2,3,DPG and the
ability of this blood to release oxygen is reduced.
Question 95
Regarding Hb, which of the following statements is
correct?
Your answer was not correct
A Fe3+ binds O2 Your Answer
B HbF has no beta chain Correct Answer
C Globin is synthesized from porphyrin
D It has an oxygen binding capacity of 1.7-1.8ml O2 per
gram of Hb
Explanation
HbF is foetal Hb and the beta chain is replaced by gamma chains
Question 96
Which of the following causes a reduction in HbO2 affinity?
Your answer was not correct
A Acidosis Your Answer
B Increased 2,3- diphosphoglycerate (DPG)
C Increased temperature
D All of the above Correct Answer
Explanation
When any of the above occur, a higher pO2 is required for Hb to bind to
a given amount of O2
Question 97
2,3-diphosphoglycerate (DPG) is decreased in all
of the following except?
Your answer was not correct
A stored blood Your Answer
B Polycythaemia
C The presence of testosterone Correct Answer
D Acidosis
Explanation
Thyroid hormone, growth hormone and androgens all increase the
concentration. Acidosis inhibits red cell glycolysis and causes the levels
to fall. Red cell 2,3 DPG concentration is increased in anaemia and in a
variety of diseases where there is chronic hypoxia. Ascent to high
altitudes also triggers a rise. Exercise has been reported to increase the
levels within 60 min. Stored blood has lower levesl of 2,3,DPG and the
ability of this blood to release oxygen is reduced.
Question 98
2,3-diphosphoglycerate (DPG) levels are increased
in?
Your answer was correct
A Chronic hypoxia Correct Answer
B Decreased temperature
C Hypocarbia
D Acidosis
Explanation
Thyroid hormone, growth hormone and androgens all increase the
concentration. Acidosis inhibits red cell glycolysis and causes the levels
to fall. Red cell 2,3 DPG concentration is increased in anaemia and in a
variety of diseases where there is chronic hypoxia. Ascent to high
altitudes also triggers a rise. Exercise has been reported to increase the
levels within 60 min. Stored blood has lower levesl of 2,3,DPG and the
ability of this blood to release oxygen is reduced.
Question 99
Which cells secrete intrinsic factor?
Your answer was not correct
A Chief cells Your Answer
B G cells
C S cells
D Parietal Correct Answer
Explanation
Chief cell of the stomach secrete pepsinogen and rennin. S cells
secrete secretin from the jejunum and the duodenum. G cell secretes
gastrin
Question 100
The pH of pancreatic secretions is around?
Your answer was not correct
A 6 Your Answer
B 6.5
C7
D 7.5 Correct Answer
Explanation
the value is around 7.5-8.0
Question 101
Regarding bile composition, which of the following
substances makes up the largest proportion?
Your answer was correct
A Bile salts Correct Answer
B Bile pigments
C Cholesterol
D Lecithin
Explanation
Water makes up the greatest composition-97%
bile salts-0.7%
bile pigments-0.2%
cholesterol 0.06%
lecithin 0.1%
Question 102
Which of the following statements is correct in
relation to gastric emptying?
Your answer was correct
A Occurs in approximately 2 hours Correct Answer
B Depends on osmotic pressure in the duodenum
C Is independent of pH in the duodenum
D Is slowed down with metoclopramide
Explanation
Gastric emptying occurs in approximately 2hours, starting with
carbohydrates, then proteins followed by fats. The rate of emptying also
depends on the osmotic pressure of the material entering the
duodenum. Hyperosmolality of the duodenal contents is sensed by the
duodenal osmoreceptors that initiate a decrease in gastric emptying.
Metoclopramide is a prokinetic. Gastric emptying is dependent on the
duodenum having an alkaline pH as an acidic pH delays gastric
emptying
Question 103
The majority of water ingested is re-absorbed in
which of the following areas?
Your answer was not correct
A Stomach Your Answer
B Jejunum Correct Answer
C Ileum
D Colon
Explanation
Daily water turnover (ml) in the GIT tract
Ingested: Total 2000ml
Endogeneous secretion: Total 7000ml
Salivary glands 1500
Stomach 2500
Bile 500
Pancreas 1500
Intestine 1000
Total reabsorbed: 8800ml
Jejunum 5500
Ileum 2000
Colon 1300
Therefore balance in stool 200
Question 104
Concerning pancreatic secretions, which of the
following statements is correct?
Your answer was not correct
A The pancreas secretes gastrin Your Answer
B pH is 6.0
C It contains anti-trypsin molecules
D Pancreatic alpha amylase also acts on ingested
polysaccharides Correct Answer
Explanation
Pancreatic secretions are alkaline with a pH 8.0. The gastric mucosa
secretes gastrin. Antitrypsin is formed in the liver
Question 105
Which of the following is a nutritionally essential
amino acid?
Your answer was not correct
A Cysteine Your Answer
B Glycine
C Histidine Correct Answer
D Tryptophan
Explanation
Nutritional essential aminoacids include: Valine, Leucine, Isoleucine,
Threonine, Methionine, Phenylalanine, Arginine, Lysine, Histidine
Question 106
Which of the following statements is true regarding
faeces?
Your answer was not correct
A 50 ml is produced per day on average Your Answer
B Solids form 75% of its composition
C The solid portion contains 30% bacteria Correct Answer
D The brown colour is due to melanin
Explanation
200-250mls of faeces is produced a day. Water forms 75% of the
composition. The brown colour is due to bile pigments. Only 25% is of
solid material
Question 107
Regarding absorption, which of the following
statements is false?
Your answer was not correct
A Glucose absorption is an example of secondary active
transport Your Answer
B Galactose is absorbed by the same mechanism as
glucose
C Fructose is absorbed by facilitated diffusion
D Insulin regulates glucose absorption in the intestine
Correct Answer
Explanation
Insulin has little to no effect on glucose absorption in the intestine
Question 108
With regard to protein digestion, which of the
following statements is correct?
Your answer was not correct
A Commences on the action of saliva Your Answer
B Protein digestion begins in the duodenum
C Pancreatic enzymes are the most important
D It is largely completed in the small intestine Correct
Answer
Explanation
Protein digestion begins in the stomach and is not dependent on
stimulation by saliva. Stomach and pancreatic enzymes both have an
important role in protein digestion.
Question 109
With regards to iron absorption, which of the
following statements is correct?
Your answer was correct
A Is increased by Vitamin C Correct Answer
B Is constant regardless of need
C Occurs in the duodenum only
D Requires intrinsic factor
Explanation
Iron absorption is regulated by recent dietary intake, state of iron stores
in the body and the state and level of erythropoeisis in the bone marrow
Question 110
Regarding fat digestion which of the following
statements is false?
Your answer was correct
A Mostly occurs in the duodenum Correct Answer
B Colipase is required for optimal activity of pancreatic
lipase
C Lipase is found in the stomach, but has no real role there
D Fat is transported in chylomicrons
Explanation
Long chain free fatty acids (FFA) are absorbed in the greatest amounts
in the upper parts of the small intestine but appreciable amounts are
also absorbed in the ileum
Question 111
Regarding absorption of amino acids, which of the
following statements is correct?
Your answer was correct
A They are co-transported with ions Correct Answer
B The enzyme trypsin begins protein digestion in the
stomach
C Approximately 75% of digested protein comes form
ingested food
D Absorption starts in the mouth
Explanation
Protein digestion begins in the stomach and absorption takes place rapidly in the
duodenum and jejunum but slowly in the ileum. At least seven different transport
systems are required for absorption. Three require NA, two both Na and Cl and two
transport amino acids independent of ions. Only 2-6% of proteins escape digestion.
Approximately 50% of the digested protein comes form ingested food, 25% from
proteins in digestive juices and 25% of proteins from desquamated mucosal cells.
Pepsin hydrolysis the bonds between tyrosine or phenylalanine and a second amino
acid. So the products of pepsin digestion are polypeptides of very diverse sizes.
Trypsin-in the small intestine begins to digest these polypeptides into free amino acids
Question 112
Regarding fat digestion and absorption, all the
following statements are correct with the exception
of?
Your answer was not correct
A Pancreatic dysfunction may lead to steatorrhea Your
Answer
B Greatest absorption occurs mostly in the ileum Correct
Answer
C Transport is in chylomicrons
D Free fatty acids (FFA) diffuse passively through the
brush border of enterocytes
Explanation
Long chain FFA absorption is greatest in the upper parts of the small
intestine, although appreciable amounts are also absorbed in the ileum.
Cholesterol is readily absorbed from the small intestine. Steatorrhea
that is caused due to pancreatic dysfunction is mostly due to lipase
deficiency. Although fats enter the enterocytes by passive diffusion,
there is some evdence to suggest that carriers are involved.
Question 113
Vitamin A, K and D are all absorbed in?
Your answer was not correct
A The stomach Your Answer
B The duodenum
C The terminal ileum
D The proximal small bowel Correct Answer
Explanation
Most vitamins are absorbed in the upper small intestines. B12, however,
is absorbed in the ileum.
Question 114
Which of the following is not a glucocorticoid
effect?
Your answer was not correct
A Increased protein catabolism Your Answer
B Increased glucose 6 phosphatase
C Increased transamination/deamination of amino acids
D Decreased glycogen synthetase Correct Answer
Explanation
Glucocorticoids increase glycogen synthetase and decrease peripheral
glucose utilization.
Question 115
Which of the following statements is true regarding
insulin?
Your answer was not correct
A Is a triple helical polypeptide Your Answer
B Is synthesised as a prohormone Correct Answer
C Binds at cytoplasmic receptor sites
D Causes K+ to leak out of cells
Explanation
Insulin is a polypeptide containing two chains of amino acids linked by
disulphide bridges. It is synthesized in the rough endoplasmic reticulum
of the beta cells of the pancreas. Half-life of insulin is 5 -10 min. It is an
anabolic hormone, which binds to its transmembrane receptors. Note
that insulin receptors are found on many different cells in the body,
including cells in which insulin does not increase glucose uptake. Insulin
cause the movement of potassium into cells. Like other polypeptide
hormones and related proteins that enter the endoplasmic reticulum,
insulin is synthesised as part of a larger perprohormone. I.e.
preproinsulin-proinsulin-insulin
Question 116
Insulin secretion is stimulated by all of the
following except?
Your answer was not correct
A Glucagon Your Answer
B Noradrenaline Correct Answer
C Leucine
D Acetylcholine
Explanation
Factors inhibiting insulin secretion: Adrenalin, noradrenaline, somatostatin, thiazide
diuretics, K depletion, phenytoin, insulin (itself), diazoxide, beta blockers and galanin.
Question 117
With regard to adrenal physiology which of the
following statements is correct?
Your answer was not correct
A Glucacorticoids exert their action by cyclic guanosine
monophosphate (cGMP) activation Your Answer
B Cortisol has no mineralocorticoid activity
C The largest steroid molecules are the oestrogens
D Dopamine is secreted by the adrenal medulla Correct
Answer
Explanation
Glucocorticoids are intranuclear hormones and attach onto nuclear
receptors. Cortisol has a predominantly glucocorticoid effect and some
mineralcorticoid activity. Oestrogen molecules are only 18C (carbon),
testosterone has 19C, progesterone has 21C and cholesterol has 27 C
Question 118
A deficiency of parathyroid hormone (PTH) is
likely to lead to which of the following?
Your answer was not correct
A Hypophosphataemia Your Answer
B The formation of kidney stones
C Neuromuscular hyperexcitability Correct Answer
D Cystic bone disease
Explanation
A lack of PTH will cause a rise in phosphate and a decrease in plasma
Ca. PTH causes bone resorption and thus cystic disease and may lead
to kidney stones. Hypocalcaemia leads to neuromuscular hyperactivity
giving rise to Chvosteks and Trosseaus signs.
Question 119
With regard to thyroid physiology, which of the
following statements is correct?
Your answer was not correct
A T3 and T4 are metabolised in the spleen and bone
marrow Your Answer
B T3 and T4 bind and act at the same cell membrane
receptor
C T4 is synthesised from tyrosine held in thyroglobulin
Correct Answer
D T3 is bound to a complex polysaccharide in the plasma
Explanation
T3 and T4 are metabolized in the liver and kidneys. They act on nuclei
receptors. T3 is more active than T4 and T3 is bound to protein
Question 120
Which of the following statements is correct
regarding glucagon?
Your answer was not correct
A It is secreted by the pancreatic beta cells Your Answer
B It increases glycogen formation
C It has a half life 30 minutes
D It stimulates insulin secretion Correct Answer
Explanation
Glucagon is secreted by the alpha cells of the pancreas. It stimulates
gluconeogenesis to produce glucose. Half life is 5-10min
Question 121
Regarding insulin, which of the following
statements is correct?
Your answer was not correct
A It increases protein catabolism in muscle Your Answer
B Its secretion is inhibited by somatostatin Correct
Answer
C Its secretion is stimulated by phenytoin
D It causes decreased K+ uptake into adipose tissue
Explanation
Insulin is an anabolic hormone, the net effect of which is storage of
carbohydrate, fat and protein. Many substances inhibit insulin including
phenytoin. It increase K uptake and is acutely effective in the treatment
of hyperkalaemia.
The following cause insulin stimulation:glucose, mannose, amino acids,
ACH, glucagon, B adrenergic stimulators and sulfonylurease.
Insulin inhibitors include: alpha adrenergic stimulators, beta blockers,
thiazide diuretic, insulin, diazoxide.
Question 122
Regarding thyroid hormones, which of the
following statements is false?
Your answer was correct
A They increase plasma cholesterol Correct Answer
B They increase the activity of Na/K-ATPase
C They alter the proportion of alpha myosin heavy chains
D They have a calorigenic action
Explanation
Thyroid hormones alter the alpha portions of heavy chain. They
increase both the number and affinity of the beta adrenergic receptors.
They increase activity of the NA/K-ATPase
Question 123
With regard to cortisol, which of the following
statements is false?
Your answer was not correct
A It is predominantly metabolised in the liver Your Answer
B It has a permissive action on vascular reactivity
C It has greater mineralocorticoid activity than
glucocorticoid activity Correct Answer
D Corticosterone is a precursor to cortisol
Explanation
Cortisol has predominately glucocorticoid and some mineralocorticoid
activity. Dexamethasone has only glucocorticoid activity and
aldosterone, which is also a glucocorticoid, has high mineralocorticoid
activity.
Question 124
Hypothyroidism results in all of the following
except?
Your answer was not correct
A Coarse hair Your Answer
B Cretinism
C W eight gain
D Early genital development Correct Answer
Explanation
Features of Hypothyroidism include
- A decrease in basal metabolic rate of up to 40%
- Hair is coarse and sparse
- The skin is dry and yeollowish
- Cold is poorly tolerated
- The voice is husky and slow
- Mentation is slow and retarted
- weight gain
- Water retension
Cretinism is a condition of severely stunted physical and mental
growth due to untreated congenital deficiency of thyroid hormones
(congential hypothyroidism) usually due to maternal hypothyrodism
Question 125
Regarding parathyroid hormone (PTH), which of
the following statements is correct?
Your answer was correct
A It causes a low phosphate (PO4) Correct Answer
B It is released when there is a rise in blood calcium levels
C Blocks vitamin D synthesis
D Raises serum Mg
Explanation
PTH acts directly on bone to increase bone resorption and mobilize Ca.
It also depresses plasma PO4. PTH increases phosphate excretion in
the urine, due to a decrease in reabsorption of PO4 in the proximal
convoluted tubules
Question 126
Which of the following is not a gastrointestinal
hormone?
Your answer was not correct
A Secretin Your Answer
B Cholecystokinin (CCK)
C Vasoactive intestinal peptide (VIP)
D Enteropeptidase (EP) Correct Answer
Explanation
Enteropeptidase is a brush border enzyme that converts trypsinogen into the active
enzyme trypsin. The rest are biological active polypeptides that are secreted by nerve
and gland cells in the mucosa and act in a paraendocrine fashion. These
gastrointestinal hormones play an important role in gastrointestinal secretion and
motility
Question 127
Which of the following does not utilise the same
receptor effector pathway?
Your answer was not correct
A Adrenalcorticotrophic hormone (ACTH) Your Answer
B Parathyroid hormone (PTH)
C Glucagon
D Insulin Correct Answer
Explanation
Glucagon, parathyroid hormone (PTH) and adrenalcorticotrophic hormone (ACTH) all
function as extracellular ligands which bind to a receptor and activate the secondary
messenger cyclic adenosine monophosphate (cAMP).
Insulin functions via the ligand regulated transmembrane enzyme signaling pathway
(tyrosine kinase)
Question 128
Which of the following is caused by thyroid
hormones?
Your answer was not correct
A Thyroid hormones cause increased expression of the of
the B-myosin heavy chain Your Answer
B Increased number but not affinity of beta adrenergic
receptors
C Decreased activity of Na/K ATP-ase
D Increased number of LDL-receptors Correct Answer
Explanation
Thyroid hormones caues increased expression of the A-MHC and a
decrease in B-MHC. The converse occurs in hypothyroidism. They
increase both the number and affinity of the beat adrenergic receptors.
They increase activity of the NA/K-ATPase
Question 129
Which of the following is correct regarding thyroid
hormone?
Your answer was not correct
A Has no effect on beta adrenergic receptor numbers Your
Answer
B Acts on a cell surface receptor
C Decreases metabolic rate
D Increases Na/K-ATPase function Correct Answer
Explanation
Thyroid hormone acts on the nucleus and causes an increase in
metabolic rate. Thyroid hormone increases both the affinity and the
number of beta adrenergic receptors
Question 130
Which of the following is not produced in the
Kreb's (citric acid) cycle?
Your answer was not correct
A CO2 Your Answer
B H+ ions
C NAD+ Correct Answer
D guanosine triphosphate (GTP)
Explanation
In the Kreb's cycle NAD changes to NADH + H
Question 131
In relation to adenosine triphosphate (ATP), which
of the following statements is correct?
Your answer was not correct
A ATP is a combination of adenine ring, ribose sugar and 2
phosphate group radicals Your Answer
B ATP is present everywhere in the cytoplasm and
nucleoplasm Correct Answer
C ATP becomes guanosine triphosphate (GTP) after the
loss of one phosphate radical
D ATP is a labile chemical compound that is present in all
cells
Explanation
ATP has 3 phosphate rings; ATP becomes adenosine diphosphate
(ADP) after the loss of one phosphate radical. ATP is a more stable
compound.
Question 132
The majority of heat lost by the body at 21 degrees
is by which of the following mechanisms?
Your answer was correct
A Radiation Correct Answer
B Sweating
C Defaecation
D Urination
Explanation
At 21 C body heat is lost by;
- radiation/conduction (70%)
- vaporization of sweat (27%)
- respiration (2%)
-
urination and defecation (1%)
Question 133
Which of the following has the highest molecular
weight (daltons)?
Your answer was not correct
A Beta 1 globulin Your Answer
B Fibrinogen Correct Answer
C Albumin
D Alpha globulin
Explanation
HB - 64450
Beta 1 globulin - 64450
Fibrinogen - 340000
Albumin 69000
Alpha globulin - 90000-150000
Question 134
Regarding the respiratory quotient (RQ), which of
the following is false?
Your answer was not correct
A Average is about 0.82 for proteins Your Answer
B RQ of brain tissue is approximately 1.00
C RQ of carbohydrate is 1.00
D RQ of fat is 0.90 Correct Answer
Explanation
RQ of the brain is regularly 0.97-0.99, indicating that its principal but not
its only fuel is carbohydrate. RQ of fat is 0.7 and for cardohydrates is
1.00. This is because H and O are present in carbohydrates in the same
proportion as in water, whereas in the various fats, extra O2 is
necessary fro the formation of H2O
Question 135
Regarding carbohydrate homeostatis in exercise,
which of the following is incorrect?
Your answer was not correct
A Initially muscle utilizes glycogen stores Your Answer
B Muscle utilizes fatty acids for its metabolism after
exercise
C plasma glucose rises due to increased gluconeogenesis
Correct Answer
D Insulin secretion decreases
Explanation
during exercise, the caloric needs of muscle are initially met by
glycogenolysis in muscle and increased uptake of glucose. plasma
glucose initially rises with increased hepatic glycogenolysis but may fall
with strenuous, prolonged exercise. Gluconeogenesis is increased,
plasma insulin falls, plasma glucagon and adrenaline rise
After exercise, liver glucagon is replenished by additional
gluconeogenesis and a decrease in hepatic glucose output.
Question 136
All of the following plasma proteins are
synthesised in the liver except?
Your answer was not correct
A Complement Your Answer
B Plasminogen
C Albumin
D Platelet-activating factor (PAF) Correct Answer
Explanation
Platelet-activating factor (PAF) is produced by neutrophiles, basophiles, platelets, and
endothelial cells
Question 137
Regarding vitamin D production, which of the
following statements is false?
Your answer was correct
A 1-hydroxylation occurs in the liver Correct Answer
B 25-hydroxylation occurs in the liver
C 1,24,25 dihydroxycholecalciferol occurs in the kidney
D Previtamin D3 to Vitamin D3 occurs in the skin
Explanation
Vitamin D3 is produced in the skin from 7-dehydrocholesterol by the
action of sunlight. Vitamin D3 is metabolised by enzymes of the
cytochrome P450 superfamily. 25-hydroxylation occurs in the liver,
converting Vitamin D3 into 25-Hydroxycholecalciferol. In the kidney, 25hydroxycholecalciferol is converted into 1,25 dihydroxycholecalciferol
(Calcitriol) by 1∝hydroxylation, and also into the less active 24,25
dihydroxycholecalciferol. by 24-hydroxylation.
Question 138
The liver produces all the following except?
Your answer was not correct
A Albumin Your Answer
B Gamma Globulins Correct Answer
C Fibrinogen
D Coagulation factors
Explanation
Gamma globulins are produced in plasma cells
Question 139
A subject is injected with a substance that: caused
slight increase in heart rate, no change in BP,
decreased sweating, pupillary dilatation but did not
impair ejaculation. It was most likely which of the
following?
Your answer was not correct
A A nicotinic antagonist Your Answer
B A dopamine antagonist
C An alpha blocker
D A muscarinic antagonist Correct Answer
Explanation
Anticholinergic drugs acting on the muscarinic receptor giving the classical features of:
- red as a beet (vasodilatation)
- dry as a chip (decreased sweating)
- blind as a bat (papillary vasodilatation)
- mad as a hater (delirium)
Question 140
Inhibitory neurotransmitters increase the post
synaptic conductance of which of the following?
Your answer was not correct
A Magnesium Your Answer
B Sodium
C Chloride Correct Answer
D Calcium
Explanation
Chloride conductance is important to both gama-aminobutyric acid (GABA) and glycine
functioning as inhibitory neurotransmittors
Question 141
All the following are neurotransmitters except?
Your answer was not correct
A Serotonin Your Answer
B Glutamate
C Adenosine
D Insulin Correct Answer
Explanation
Insulin is a hormone; a polypeptide containing 2 chains of amino acids linked by disulfide
bridges
Question 142
Which of the following is correct in relation to true
acetylcholinesterase?
Your answer was not correct
A Forms acetylcholine from acetate Your Answer
B Is produced by the liver
C Functions only at nerve endings Correct Answer
D Is involved in gama-aminobutyric acid (GABA)
metabolism
Explanation
Acetylcholinesterase (ACH) breaks down acetylcholine. ACH is formed in the cytoplasm of
nerve endings. If ACH functions in the plasma it is called pseudocholinesterase
Question 143
In the formation of adrenaline, which of the
following is correct?
Your answer was not correct
A Catechol-o-methyl transferase (COMT) produces
adrenaline from noradrenaline Your Answer
B Phenylalanine is converted to tyrosine Correct Answer
C Serotonin is a vital intermediate step
D Dopa is formed from dopa decarboxylase
Explanation
Both noradrenaline (NA) and adrenaline are metabolized to inactive products by catechol-omethyl transferase (COMT) and monoamine oxidase inhibitors (MAOI). Dopa, dopamine and
NA are important steps in the formation of adrenaline. Dopa is formed from tyrosine
hydroxylase
Question 144
Monoamine oxidase (MAO) breaks down which of
the following?
Your answer was not correct
A Glutamate Your Answer
B Serotonin Correct Answer
C Tryptophan
D Glycine
Explanation
MAO breaks down noradrenaline, adrenaline, serotonin, and dopamine
Question 145
Which of the following has the most effect on
smooth muscle relaxation?
Your answer was correct
A Isoprenaline Correct Answer
B Adrenaline
C Dopamine
D Noradrenaline
Explanation
Isoprenaline has pure B1 and B2 effects. More so than adrenaline,
noradrenaline and dopamine. Isoprenaline will cause pure smooth
muscle relaxation. Dopamine in higher doses will activate beta and then
alpha receptors. Adrenaline in higher doses will also activate alpha
receptors.
Question 146
Anterolateral dissection of the spinal cord is
associated with which of the following?
Your answer was not correct
A Ipsilateral loss of pain Your Answer
B Ipsilateral loss of temperature
C Ipsilateral hyperreflexia Correct Answer
D Contralateral vibration loss
Explanation
Loss of pain and temperature occurs after damage to the spinothalamic tract which crosses at
the spinal cord level and thus will be contralateral. Vibration sense is mediated by the posterior
columns and thus is not affected.
Question 147
Alpha 1 stimulation will lead to which of the
following?
Your answer was correct
A Contraction of bladder trigone and sphincter Correct
Answer
B Bronchial smooth muscle contraction
C Pupillary constriction
D Increased atrio-ventricular (AV) conduction
Explanation
Common effects of the alpha one receptor stimulation include:
Vasoconstriction of coronary arteries and veins
Decreased motility of the smooth muscle in the gastrointestional tract (GIT)
Smooth muscle vasoconstriction
Question 148
Which of the following is correct in relation to the
sensation for cold stimuli?
Your answer was correct
A Is relayed by the thalamus Correct Answer
B Is transmitted by the dorsal columns
C Is an uncrossed sensory modality
D Is mediated by A alpha fibres
Explanation
The sensation for cold is transmitted by the lateral spinothalamic tracts
and is a crossed sensorimodality. It is mediated by type A delta fibres
Question 149
The major excitatory transmitter in the spinal cord
is which of the following?
Your answer was not correct
A Glycine Your Answer
B Aspartate
C Glutamate Correct Answer
D Gama-aminobutyric acid (GABA)
Explanation
Glutamate is the main excitatory transmitter in the brain and spinal cord. Aspartate is also
excitatory. GABA and Glycine are inhibitory
Question 150
The most visually sensitive part of the eye is?
Your answer was not correct
A Choroid Your Answer
B Fovea centralis Correct Answer
C Optic disc
D Retina
Explanation
In the human eye the term fovea (or fovea centralis) denotes the pit in the macular part
of the retina, which allows for maximum acuity of vision.
Question 151
Which of the following most easily penetrates the
cerebro-spinal fluid (CSF)?
Your answer was not correct
A H2O Your Answer
B CO2 Correct Answer
C N2O
D O2
Explanation
H and HCO3 penetrate slowly as compared to CO2, which has
physiologic significance in the regulation of respiration. Lipid soluble
free forms of steroid hormones also penetrate easily. Proteins do not.
Question 152
The kappa receptor is responsible for which of the
following?
Your answer was correct
A Analgesia, sedation, and dysphoria Correct Answer
B Dysphoric reactions and hallucinations
C Euphoria, dependence, and analgesia
D Sedation, dysphoria and mydriasis
Explanation
The Kappa receptor is responsible for- analgesia, diuresis, sedation, miosis and dysphoria
The Mu receptor is reponsible for- analgesia, respiratory depression, constipation, euphoria,
sedation, miosis
The Delta receptor- analgesia
Question 153
The hypothalamus is essential for which of the
following?
Your answer was not correct
A Movement Your Answer
B Visual acuity
C Renal function
D Hunger Correct Answer
Explanation
Principal hypothalamic regulatory mechanisms include: temperature regulation,
neuroendocrine control (Catecholamines, vasopressin, oxytocin, TSH, FSH, ACTH, LH,
Prolactin and GRH), appetite, behaviour (thirst, hunger and sexual behaviour),
defensive reactions and control of body rhythms
Question 154
Which area has the best visual acuity?
Your answer was correct
A Fovea centralis Correct Answer
B Optic disc
C Area with maximal rods
D Retina
Explanation
The fovea is the point where visual acuity is the greatest
Question 155
The vestibular nerve has a direct connection to
which of the following?
Your answer was correct
A Cerebellum Correct Answer
B Oculomotor nucleus
C Cortex
D Pons
Explanation
Each vestibular nerve terminates in the ipsilateral 4-part vestibular nucleus and in the
flocculonodular lobe of the cerebellum
Question 156
Which of the following is the main inhibitory
neurotransmitter of the spinal cord?
Your answer was correct
A Glycine Correct Answer
B Gama-aminobutyric acid (GABA)
C Acetylcholine
D Dopamine
Explanation
GABA is the main inhibitory mediator in the brain, where it transmits at 20% of CNS synapses.
Glycine is also responsible for direct inhibition in the brainstem and the spinal cord. Note that
Glycine can be both inhibitory and excitatory.
Question 157
Upon skeletal muscle contraction
Your answer was not correct
A The H zone increases Your Answer
B The I zone decreases Correct Answer
C The A zone decreases
D The A and I zone increase
Explanation
Question 158
Which of the following occurs on stretching
intestinal smooth muscle?
Your answer was not correct
A It hyperpolarises Your Answer
B The tension is due to elastic forces only
C It depolarises Correct Answer
D Relaxation occurs
Explanation
Visceral smooth muscle is unique in that, unlike other types of muscle, it contracts when
stretched in the absence of any extrinsic innervation. Stretch is followed by a decline in
membrane potential, an increase in the frequency of spikes and a general increase in tone
Question 159
With respect to the cardiac action potential
Your answer was not correct
A Action potential duration is 20ms Your Answer
B Unlike nerve action potential there is no overshoot
C Duration of depolarization is 1ms
D The resting membrane potential is -90mV Correct
Answer
Explanation
Cardiac muscle cell resting membrane potential is -90MV,
depolarization lasts about 2ms. The plateau phase and repolarization
lasts 200ms or more. The initial rapid depolarization and the overshoot
(phase 0) are due to the opening of voltage-gated Na channels.
Duration of the cardiac action potential is between 200-400ms.
Question 160
Which of the following is a special feature of the
contraction of smooth muscle?
Your answer was not correct
A Actin is not involved Your Answer
B Myosin is not involved
C ATP is not the energy source
D The membrane potential is unstable Correct Answer
Explanation
Visceral muscle is characterized by the instability of its membrane potential and by the fact
that it shows continuous, irregular contractions that are independent of its nerve supply.
Calcium, actin and myosin are all involved. ATP is required for energy. In skeletal muscle there
is activation of calmodulin dependant myosin light chain kinase (Ca binds to calmodulin). With
cardiac and skeletal muscle Ca binds to troponin C
Question 161
Which of the following statements in relation to
skeletal muscle is correct?
Your answer was not correct
A The immediate energy source for contraction is GTP
Your Answer
B Troponin T inhibits the interaction of myosin with actin
C Myosin is contained entirely within the A band Correct
Answer
D Tropomysin is made up of 3 sub-units
Explanation
The immediate source of energy is ATP.
Troponin has three subunits: I, C, T. These three subunits have a
molecular weight ranging from 18000 to 35000.
Troponin I inhibits the interaction of myosin with actin. In the resting
state Troponin I covers actin and tropomyosin covers the site where
myosin head binds to actin. This troponin-tropomyosin complex
constitutes a relaxing protein that inhibits the binding of actin and
myosin
The A band contains thick filaments which are made up of myosin
Question 162
With regard to the action potential of a neuron with
a resting membrane potential (RMP) of -70mV,
which of the following statements is correct?
Your answer was not correct
A The firing level is likely to be-30mV Your Answer
B The overshoot will not extend much past 0mV
C Chloride influx will restore the membrane potential
D Increasing the external chloride ion concentration
increases the RMP Correct Answer
Explanation
The firing level is -55mv, the overshoot is +35mv, and chloride influx will not restore the RMP.
External Cl- ion concentration will increase the RMP. Remember the negative symbol infornt of
the number just represents the outside of the cell. Decreasing the RMP therefore means that
the RMP goes form -70mv to -50mv. Increasing the RMP, the RMP will go form -70mv to 90mv
Question 163
With regard to Na - K ATPase, which of the
following statements is correct?
Your answer was not correct
A Hydrolyses ADP to ATP Your Answer
B Extrudes 3 Na+ from the cell for every 2 K+ Correct
Answer
C Consists of an alpha, beta and gamma sub-unit
D Lies on the extracellular fluid (ECF) side of the
membrane
Explanation
Na/K ATPase hydrolyses ATP to ADP. It consists of only two subunits, an alpha and a beta.
Both subunits extend through the cell membrane.
Question 164
In contracting skeletal muscle
Your answer was not correct
A The H zone increases Your Answer
B The I zone decreases Correct Answer
C The A zone increases
D Z zone increases
Explanation
Question 165
Regarding cardiac muscle, which of the following
statements is correct?
Your answer was not correct
A Gap junctions resist the flow of ions Your Answer
B There are no Z bands
C It resembles skeletal muscle Correct Answer
D Its intercalated discs are loosely attached
Explanation
Cardiac muscle resembles skeletal muscle and has Z lines. Along the side of the muscle
fibres, next to the disks, the cell membranes of adjacent fibres fuse for considerable distances
forming gap junctions. These gap junctions provide low resistance bridges for the spread of
excitation from one muscle to another. At the Z lines there are intercolated disc which provide a
strong union between fibres, maintaining cell to cell cohesion.
Question 166
Regarding type A nerve fibres, which of the
following is correct?
Your answer was correct
A Gamma is to motor muscle spindles Correct Answer
B Beta is to motor muscle spindles
C Alpha is to motor muscle spindles
D Sigma is to proprioceptive fibres
Explanation
Beta fibres- touch, pressure and motor.
Alpha fibres-proprioception,
somatic motor
Sigma fibres- preganglionic autonomic
Question 167
Regarding smooth muscle, initiation of contraction
is due to which of the following mechanisms?
Your answer was not correct
A Na influx Your Answer
B Cl influx
C K influx
D Ca influx Correct Answer
Explanation
Smooth muscle generally has a poorly developed sarcoplasmic reticulum, and the
increase in intracellular Ca concentration that initiated contraction is due primarily to Ca
influx from the extracellular fluid (ECF) via voltage gated and ligand gated Ca channels
Question 168
With regard to bradykinin, which of the following
statements is correct?
Your answer was not correct
A Its name is derived from its action e.g. It decreases heart
rate and causes hypotension Your Answer
B It contracts visceral muscle Correct Answer
C It contracts smooth vascular muscle
D It is not related to pain or pain sensation
Explanation
Bradykinin causes hypotension. It contracts non vascular smooth muscle and is involved with
the perception of pain.
Question 169
Regarding resting membrane potential (RMP),
which of the following statements is correct?
Your answer was correct
A Hyperkalemia decreases the resting membrane potential
Correct Answer
B A decreased extracellular Na concentration decreases
the resting membrane potential
C During the action potential, Na exits the cell and K enters
the cell
D Hypercalcaemia increases the excitability of nerve and
muscle cells
Explanation
Hyperkalaemia decreases the RMP and brings it closer to zero. RMP of -90mv for
example decreases to -70mv. The "-" reflects the ion type found on one side of the
membrane. The other being "+" (It does not represent a negative value). Decreasing the
extracellular sodium (Na) concentration decreases the size of the action potential but
has little effect on the RMP. During the action potential, Na enters and K exists the cell.
Question 170
Calmodulin is involved in which of the following?
Your answer was not correct
A Smooth muscle relaxation Your Answer
B Smooth muscle contraction Correct Answer
C Skeletal muscle contraction
D Skeletal muscle relaxation
Explanation
Calmodulin is also involved in synaptic function, protein synthesis, activating calcium channels
and t cells, and activating phosphorylase
Question 171
The most important ion for cardiac resting
membrane (CRM) potential is?
Your answer was not correct
A Na Your Answer
B Ca
C K Correct Answer
D Cl
Explanation
As in other excitable tissue, changes in the external K concentration affect he resting
membrane potential of cardiac muscle, whereas changes in the external Na concentration
affect the magnitude of the action potential.
Question 172
Regarding basic physiological measures, all of the
following are true except?
Your answer was not correct
A One equivalent of Na+ is 23g/L Your Answer
B pH is the log to the base 10 of the reciprocal of hydrogen
ion concentration
C Carbon has a molecular mass of 12 dalton
D Osmolarity is affected by the volume of various solutes in
the solution and temperature Correct Answer
Explanation
Osmolarity is the number of osmoles per liter of solution.
Osmolality is the number of osmoles per kilogram of solvent.
The osmolal concentration of a substance in a fluid is measured by the degree to which it
depresses the freezing point by 1.86 degrees Celsius. Therefore osmolarity is affected by the
volume of various solutes in the solution and temperature, while the osmolality is not.
This correct answer is osmolarity not osmolality... just a typo
Question 173
What is the hydrogen ion concentration at a pH of
7.4?
Your answer was not correct
A 0.0001meq/L Your Answer
B 0.00004 meq/L Correct Answer
C 0.0003 meq/L
D 0.0002 meq/L
Explanation
pH=H ion concentration meq/L
4.5=0.03
7.0=0.0001
7.7=0.00002
8.0=0.00001
Question 174
The ratio of HCO3- ions to carbonic acid at a pH of
7.1 is?
Your answer was not correct
A 100 Your Answer
B 0.1
C 10 Correct Answer
D1
Explanation
pH - ratio.
6.0=0.9,
7.1=10,
7.3=16
7.4=20,
Note: This question is taken form a figure in the chapter 39- from Ganong.
The equation to work out the ratios:
pH=pKa + log (HCO3/H2CO3)
pKa=6.1 and the H2CO3 is in equilibrium with CO2
Therefore
pH=6.1 + log {[HCO3]/0.0301PCO2}
It does appear that the question is taken just form the figure and
therefore no calculations were needed.
Question 175
Which of the following is correct regarding the
composition of extracellular fluid (ECF) when
compared to that of intracellular fluid (ICF)?
Your answer was not correct
A ECF has a decreased sodium concentration Your
Answer
B ECF has an increased magnesium concentration
C ECF has a decreased phosphate concentration Correct
Answer
D ECF has an increased potassium concentration
Explanation
Intracellular fluid has the highest concentration of phosphate. 99% of
magnesium is intracellular or in bone
Question 176
Regarding the composition of extracellular fluid
(ECF) compared to that of intracellular fluid (ICF),
which of the following statements is correct?
Your answer was not correct
A ECF has a decreased sodium concentration Your
Answer
B ECF has an increased potassium concentration
C ECF has an increased phosphate concentration
D ECF has a decreased magnesium concentration Correct
Answer
Explanation
Intracellular fluid has the highest concentration of phosphate. 99% of
magnesium is intracellular or in bone
Question 177
With regard to total body water (TBW), which of
the following statements is correct?
Your answer was not correct
A Increases with age Your Answer
B Is typically 45% of bodyweight
C Is typically 63% of body weight
D Is greater in men than women Correct Answer
Explanation
Total body fluid decreases with age, is typically around 60% of body weight and is composed
largely of intracellular fluid
Question 178
1 litre of 5% dextrose given intravenously would
distribute predominantly to?
Your answer was not correct
A Intravascular compartment Your Answer
B Intracellular compartment Correct Answer
C Interstitial compartment
D Extracellular compartment
Explanation
A 5% dextrose solution is similar to the infusion of pure water, and
water distributes itself evenly throughout the body spaces. Therefore,
most will go to the ICF due to its percentage. Some goes interstitial and
some stays intravascular.
Question 179
With regard to the composition of cerbro-spinal
fluid (CSF), which of the following statements is
correct?
Your answer was not correct
A Production is 50-100 mls per day Your Answer
B Has the same composition as cerebral extracellular fluid
(ECF) Correct Answer
C Higher concentration of K+ with respect to plasma
D Higher concentration of protein
Explanation
Question 180
Looking at the contents of a litre bag of 0.9%
Sodium Chloride solution, Which of the following
is incorrect?
Your answer was not correct
A There is 9g of sodium chloride/1000ml Your Answer
B The osmolality is approximately 275 mOsm Correct
Answer
C Approximatly 150mmol/L of sodium
D pH range 4.0-7.0
Explanation
A litre bag of 0.9%NACL
Each 1000ml contains NACL 9grams
Approximately 150mmols of Na and Cl per 10000ml
pH range 4.0-7.0
Approximate osmolality 300mOsm
Question 181
Regarding intracellular fluid (ICF), which of the
following is incorrect?
Your answer was correct
A Na+ of 135 Correct Answer
B K+ of 140
C Mg2+ of 58
D PO4- of 75
Explanation
Intracellular sodium level is 15 mmol/L
Question 182
Which of the following is not a function of the
smooth endoplasmic reticulum (SER)?
Your answer was not correct
A Role in carbohydrate metabolism Your Answer
B Steroid synthesis
C Drug detoxification
D Protein synthesis Correct Answer
Explanation
Protein synthesis occurs in the granular endoplasmic reticulum (GER).
The SER synthesizes lipids and steroids, metabolize carbohydrates and
steroids, regulates calcium concentration, drug detoxification and
attachment of receptors on cell membrane proteins. Sarcoplasmic
reticulum solely regulates calcium levels.
Question 183
Which of the following accounts for 20% of total
body weight?
Your answer was correct
A Extracellular fluid (ECF) Correct Answer
B Intracellular fluid (ICF)
C Total body water (TBW)
D Blood volume
Explanation
ECF=20%
TBW=60%
Plasma=5%
ICF=40%
Question 184
The main buffer in interstitial fluid is?
Your answer was correct
A Bicarbonate Correct Answer
B Haemoglobin
C Phosphate
D Ammonia
Explanation
Blood- Bicarbonate, protein and HB. Interstitial fluid- Bicarbonate. Intracellular fluid- Proteins,
phosphate. CSF and urine- Bicarbonate and phosphate
Question 185
Which of the following penetrates cerebro-spinal
fluid (CSF) most easily?
Your answer was not correct
A HCO3 Your Answer
B H2O, CO2, O2 Correct Answer
C Na, K, Cl
D N2O
Explanation
H and HCO3 penetrate slowly as compared to CO2, which has physiologic significance in the
regulation of respiration. Lipid soluble free forms of steroid hormones also penetrate easily,
whereas proteins do not.
Question 186
Regarding body fluid composition, which of the
following accounts for approximately 40% of
bodyweight?
Your answer was correct
A Intra cellular fluid (ICF) Correct Answer
B Extra cellular fluid (ECF)
C Total body water (TBW)
D Plasma
Explanation
ECF=20%
TBW=60%
Plasma=5%
Question 187
Regarding cerebro-spinal fluid (CSF), Which of the
following statements is correct?
Your answer was not correct
A 50 to 100ml /day is produced Your Answer
B Drained through choroid plexus
C Greater protein content than blood
D Content essentially same as brain extra cellular fluid
(ECF) Correct Answer
Explanation
The volume of CSF fluid produced a day is 150ml and the rate of CSF production is
about 550ml/d. Thus CSF turns over about 3.7 times a day. 50-70% is formed in the
choroid plexuses and the remainder is formed around blood vessels and along
ventricular walls. Protein content in CSF is 20.0 mg/dl and plasma is 6000mg/dl. The
composition of CSF is essentially the same as that of brain ECF, which in humans
makes up 15% of the brain volume.