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MCQOPTIONS
This section includes 697 Mcqs, each offering curated multiple-choice questions to sharpen your Biology knowledge and support exam preparation. Choose a topic below to get started.
| 401. |
The primary reason for the decreased medullary hypertonicity associated with osmotic diuresis is: |
| A. | an associated increased urine volume |
| B. | the limiting concentration gradient for sodium reabsorption is reached |
| C. | tubular fluid has an increased sodium concentration |
| D. | the total amount of sodium reaching the loop of Henle is increased |
| E. | the associated maximal vasopressin secretion |
| Answer» C. tubular fluid has an increased sodium concentration | |
| 402. |
A 28-year-old lady has taken an overdose of sedatives causing her to hypoventilate. Given that her arterial PCO2 is now doubled to 80mmHg, which of the following is most likely to be correct, given that she is breathing room air at normal barometric pressures? |
| A. | arterial PO2 will be approximately 70mmHg |
| B. | arterial PO2 will be approximately 35mmHg |
| C. | arterial Hb O2 saturation will be approximately 50% |
| D. | arterial Hb O2 saturation will be approximately 80% |
| E. | arterial Hb O2 saturation will be approximately 27% |
| Answer» E. arterial Hb O2 saturation will be approximately 27% | |
| 403. |
With regard to anatomic dead space, all of the following are true EXCEPT: |
| A. | it is calculated by Bohr s method |
| B. | the normal value is about 150ml |
| C. | it increases with large inspirations |
| D. | depends on the size of the subject |
| E. | it is equivalent to the conducting zone |
| Answer» B. the normal value is about 150ml | |
| 404. |
Given a PCO2 = 600mmHg and a HCO3- = 28mEq/l there is a: |
| A. | metabolic acidosis |
| B. | metabolic acidosis with renal compensation |
| C. | respiratory acidosis |
| D. | respiratory acidosis with renal compensation |
| E. | respiratory alkalosis |
| Answer» D. respiratory acidosis with renal compensation | |
| 405. |
Concerning the kidneys: |
| A. | normal glomerular filtration rate is 250ml/minute |
| B. | normal renal plasma flow is 125ml/minute |
| C. | normal filtration fraction is 0.19 |
| D. | blood flow is normally higher in the medulla than the cortex |
| E. | normal blood volume in the kidneys at any one time is 250ml |
| Answer» D. blood flow is normally higher in the medulla than the cortex | |
| 406. |
Renal autoregulation of GFR helps prevent large fluctuations in GFR despite wide variations in arterial blood pressure. With regard to autoregulation, which is TRUE? |
| A. | the macula densa cells sense change in afferent arteriolar pressure |
| B. | falling GFR results in a feedback to decrease efferent arteriolar pressure |
| C. | falling GFR results in an increase in renin secretion from macula densa cells |
| D. | decreased macula densa concentration of NaCl results in dilatation of afferent arterioles |
| E. | decreased GFR decreases NaCl reabsorption in the ascending loop of Henle |
| Answer» E. decreased GFR decreases NaCl reabsorption in the ascending loop of Henle | |
| 407. |
Which of the following is INCORRECT regarding regulation of renal blood flow? |
| A. | noradrenaline constricts the renal vessels |
| B. | dopamine causes renal vasodilation and natriuresis |
| C. | angiotensin II exerts a constrictor effect on the efferent arterioles |
| D. | prostaglandins increase blood flow in the renal cortex and decrease blood flow in the renal medulla |
| E. | acetylcholine produces renal vasoconstriction |
| Answer» F. | |
| 408. |
Na+ resorption does not occur in which part of the nephron? |
| A. | proximal convoluted tubule |
| B. | thin descending loop of Henle |
| C. | thick ascending loop of Henle |
| D. | distal convoluted tubule |
| E. | collecting duct |
| Answer» C. thick ascending loop of Henle | |
| 409. |
The highest number of voltage gated Na+ channels are found in: |
| A. | initial segment of axon |
| B. | nodes of Ranvier |
| C. | cell body |
| D. | terminal buttons |
| E. | myeline sheath |
| Answer» B. nodes of Ranvier | |
| 410. |
Regarding a coronary blood flow: |
| A. | systolic blood flow in subendocardial arteries is greater than in the epicardial |
| B. | less than 50% of oxygen is removed during passage when in the resting state |
| C. | the coronary circulation is well supplied by parasympathetic vasodilatory fibres |
| D. | sympathetic vasoconstrictory fibres predominate in epicardial vessels |
| E. | none of the above |
| Answer» E. none of the above | |
| 411. |
Regarding renal blood flow: |
| A. | blood flow greatest to medulla |
| B. | pressure in renal vein is about 20mmHg |
| C. | angiotensin II constricts efferent arterioles |
| D. | prostaglandins increase blood flow in cortex and medulla |
| E. | renal blood flow = renal plasma flow x 1 haematocrit |
| Answer» D. prostaglandins increase blood flow in cortex and medulla | |
| 412. |
Regarding glomerular blood supply: |
| A. | the efferent arterioles are branches of the interlobular arterioles |
| B. | the descending vasa recta vessels contain fenestrated endothelium to assist urea transport |
| C. | the efferent arterioles empties into the peritubular network |
| D. | the glomerular capillaries drain into the efferent vein |
| Answer» D. the glomerular capillaries drain into the efferent vein | |
| 413. |
The size of the action potential is decreased by |
| A. | Decreased extracellular calcium |
| B. | Increased external sodium |
| C. | Decreased internal sodium |
| D. | Decreased internal potassium |
| E. | Increased internal potassium |
| Answer» D. Decreased internal potassium | |
| 414. |
Action potential initiation in the sinoatrial and atrioventricular nodes results from: |
| A. | Na+ influx |
| B. | K+ influx |
| C. | Ca++ influx |
| D. | Na+ and Ca++ influx |
| E. | increased K+ conductance |
| Answer» D. Na+ and Ca++ influx | |
| 415. |
Cerebellar disease in humans causes all of the following EXCEPT: |
| A. | dysmetria |
| B. | scanning speech |
| C. | lead pipe rigidity |
| D. | rebound phenomenon |
| E. | dysdiadockokinesia |
| Answer» D. rebound phenomenon | |
| 416. |
The action potential of a neuron: |
| A. | is initiated by efflux of Na+ |
| B. | is terminated by efflux of K+ |
| C. | declines in amplitude as it moves along the axon |
| D. | results in transient reversal of the concentration gradient of Na+ across the cell membrane |
| E. | is not associated with any net movement of Na+ or K+ across the cell membrane |
| Answer» C. declines in amplitude as it moves along the axon | |
| 417. |
Regarding renal handling of sodium, which is INCORRECT? |
| A. | more than 95% of filtered sodium is reabsorbed |
| B. | proximal tubular reabsorption is an example of secondary active transport |
| C. | aldosterone increases reabsorption despite increasing GFR |
| D. | glucocorticoids may increase or decrease urinary excretion |
| E. | renal oxygen consumption is directly proportional to sodium reabsorption |
| Answer» D. glucocorticoids may increase or decrease urinary excretion | |
| 418. |
Regarding renal handling of bicarbonate ion, which is INCORRECT? |
| A. | small size of bicarbonate ion affects reabsorption |
| B. | reabsorption is reciprocally related to chloride ion reabsorption in proximal tubule |
| C. | most reabsorption occurs in proximal tubule |
| D. | reabsorption requires carbonic anhydrase |
| E. | reabsorption is decreased by ECF expansion |
| Answer» B. reabsorption is reciprocally related to chloride ion reabsorption in proximal tubule | |
| 419. |
Regarding renal handling of ammonia, which is INCORRECT? |
| A. | ammonia is not filtered at the glomerulus |
| B. | ammonia is synthesised in proximal and distal tubules |
| C. | glutaminase plays a role in ammonia excretion |
| D. | non-ionic diffusion of ammonia maintains a concentration gradient for further diffusion |
| E. | ammonia diffusion can increase up to 30 fold |
| Answer» F. | |
| 420. |
Regarding renal handling of glucose, which is INCORRECT? |
| A. | transport maximum varies depending on sex |
| B. | proximal tubular absorption is an example of a symport mechanism |
| C. | not all nephrons handle glucose filtration and reabsorption equally |
| D. | phlorhizin inhibits distal tubular reabsorption |
| E. | GLUT-2 transports glucose into interstitial fluid |
| Answer» E. GLUT-2 transports glucose into interstitial fluid | |
| 421. |
Regarding renal handling of chloride, which is INCORRECT? |
| A. | about 25% of filtered load is actively reabsorbed in thick ascending limb |
| B. | proximal tubular reabsorption is reciprocally related to bicarbonate reabsorption |
| C. | it is actively secreted in distal tubule |
| D. | two chloride per sodium are reabsorbed in thick ascending limb |
| E. | chloride-hydroxide antiport are present in the kidney |
| Answer» D. two chloride per sodium are reabsorbed in thick ascending limb | |
| 422. |
Regarding renal handling of phosphate, which is INCORRECT? |
| A. | no tubular secretion occurs |
| B. | most reabsorption occurs actively in proximal tubule |
| C. | parathyroid hormone inhibits tubular reabsorption |
| D. | less than 5% of filtered load is excreted |
| E. | phosphate is a much more powerful buffer in tubular fluid than in blood |
| Answer» E. phosphate is a much more powerful buffer in tubular fluid than in blood | |
| 423. |
Chloride may be reabsorbed in the nephron by: |
| A. | passive reabsorption |
| B. | active co-transport with K+ and Na+ |
| C. | OH- /Cl- antiport |
| D. | all of the above |
| E. | none of the above |
| Answer» E. none of the above | |
| 424. |
Regarding renal handling of hydrogen ion, which is INCORRECT? |
| A. | acetazolamide decreases tubular secretion |
| B. | aldosterone increases distal tubular secretion |
| C. | much more acid secretion occurs in proximal than distal tubule |
| D. | lowest tubular fluid pH achievable is 4.5 |
| E. | secondary active transport mechanism operates in distal tubule |
| Answer» F. | |
| 425. |
85% of NaHCO3 in the filtrate is reabsorbed in the: |
| A. | proximal convoluted tubule |
| B. | descending loop of Henle |
| C. | thick ascending loop of Henle |
| D. | distal convoluted tubule |
| E. | collecting ducts |
| Answer» B. descending loop of Henle | |
| 426. |
Which of the following statements regarding angiotensin is INCORRECT? |
| A. | angiotensin II has a half-life of about 1-2 minutes |
| B. | angiotensin I is physiologically inactive |
| C. | angiotensin III has equivalent pressor activity to angiotensin II |
| D. | angiotensinogen mainly comes from the liver |
| E. | angiotensin converting enzyme is a dipeptidyl carboxypeptidase angiotensin converting enzyme |
| Answer» D. angiotensinogen mainly comes from the liver | |
| 427. |
Which is not a ligand-gated ion channel? |
| A. | nicotinic receptor |
| B. | GABAA receptor |
| C. | glycine receptor |
| D. | NMDA receptor |
| E. | 5-HT1 receptor |
| Answer» F. | |
| 428. |
Regarding the actions of angiotensin II, which is INCORRECT? |
| A. | selective renal efferent arteriolar constriction |
| B. | acts on CNS without crossing blood-brain barrier |
| C. | contract mesangial cells |
| D. | direct positive chronotropic action on heart |
| E. | increases conversion of cholesterol to pregnenelone |
| Answer» E. increases conversion of cholesterol to pregnenelone | |
| 429. |
The maximum effect of vasopressin occurs at: |
| A. | distal convoluted tubule |
| B. | proximal convoluted tubule |
| C. | cortical part of the collecting duct |
| D. | medullary part of collecting duct |
| E. | thick ascending limb of loop of Henle |
| Answer» D. medullary part of collecting duct | |
| 430. |
Angiotensin H causes: |
| A. | greater constriction of efferent than afferent arterioles |
| B. | greater constriction of afferent than efferent arterioles |
| C. | constriction of afferent arterioles only |
| D. | constriction of efferent arterioles only |
| E. | has no effect on arteriolar constriction |
| Answer» B. greater constriction of afferent than efferent arterioles | |
| 431. |
Angiotensin II causes: |
| A. | greater constriction of efferent than afferent arterioles |
| B. | greater construction of afferent than efferent arterioles |
| C. | constriction of afferent arterioles only |
| D. | constriction of efferent arterioles only |
| E. | has no effect on arteriolar constriction |
| Answer» B. greater construction of afferent than efferent arterioles | |
| 432. |
In the presence of vasopressin, most filtered water is absorbed in the: |
| A. | proximal tubule |
| B. | loop of Henle |
| C. | distal tubule |
| D. | cortical collecting system |
| E. | medullary collecting system |
| Answer» B. loop of Henle | |
| 433. |
In the presence of vasopressin, most filtered water is absorbed in the? |
| A. | proximal tubule |
| B. | loop of Henle |
| C. | distal tubule |
| D. | cortical collecting system |
| E. | medullary collecting system |
| Answer» B. loop of Henle | |
| 434. |
Angiotensin II: |
| A. | constricts afferent arterioles only |
| B. | constricts efferent arterioles only |
| C. | constricts afferent and efferent arterioles |
| D. | dilates afferent arterioles |
| E. | dilates efferent arterioles |
| Answer» D. dilates afferent arterioles | |
| 435. |
The primary effect of angiotensin II on renal vasculature is: |
| A. | constriction of efferent arterioles |
| B. | enhanced prostaglandin mediated increased blood flow to the renal cortex |
| C. | enhanced catecholamine mediated afferent arteriolar vasoconstriction |
| D. | enhanced catecholamine mediated afferent vasodilatation |
| E. | constriction of interlobular arteries |
| Answer» B. enhanced prostaglandin mediated increased blood flow to the renal cortex | |
| 436. |
Which is NOT true of osmotic diuresis? |
| A. | osmotic diuresis is due to the quantity of unreabsorbed solutes |
| B. | decreased water reabsorption in proximal tubules and loops |
| C. | reduced Na+ reabsorption as the limiting concentration gradient is exceeded |
| D. | net loss of Na+ in urine |
| E. | normal water reabsorption in proximal portion of tubules |
| Answer» F. | |
| 437. |
A tumour causing external compression to the anterior cervical spinal cord would be expected to: |
| A. | impair pressure and pain sensation mostly from sacral and lumbar areas |
| B. | impair fine touch and vibration mostly from sacral and lumbar areas |
| C. | impair pain only from cervical areas |
| D. | impair vibration sense only from cervical areas |
| E. | impair joint position from sacral areas only |
| Answer» E. impair joint position from sacral areas only | |
| 438. |
Tuboglomerular feedback refers to: |
| A. | the process of increased sodium reabsorption associated with an increased glomerular filtration |
| B. | changes in peri-tubular oncotic pressure associated with changes in glomerular filtration |
| C. | decreased glomerular filtration associated with increased flow through the loop of Henle |
| D. | increased glomerular filtration associated with decreased peri-tubular oncotic pressure |
| E. | thromboxane A2 mediated increased sodium reabsorption associated with increased renal blood flow |
| Answer» D. increased glomerular filtration associated with decreased peri-tubular oncotic pressure | |
| 439. |
Regarding osmotic diuresis: |
| A. | is secondary to decreased ADH |
| B. | results in hypertonic urine |
| C. | increased water reabsorption in PCT |
| D. | may be seen in patients with diabetes ketoacidosis |
| E. | may be seen in patients with diabetes insipidis |
| Answer» E. may be seen in patients with diabetes insipidis | |
| 440. |
Regarding synapses: |
| A. | the synaptic cleft is 30-50mm wide |
| B. | transmitters are released from synaptic knobs secondary to Na+ triggers |
| C. | the amount of transmitter released is proportionate to Ca2+ efflux |
| D. | acetylcholine is present in granulated vesicles in synaptic knob |
| E. | the EPSP is caused by Na+ influx |
| Answer» F. | |
| 441. |
At which site is sodium ion NOT actively reabsorbed? |
| A. | proximal tubule |
| B. | thin limb of loop of Henle |
| C. | thick limb of loop of Henle |
| D. | distal tubule |
| E. | collecting duct |
| Answer» C. thick limb of loop of Henle | |
| 442. |
Frusemide acts mainly at: |
| A. | proximal tubule |
| B. | thin limb of loop of Henle |
| C. | thick limb of loop of Henle |
| D. | distal tubule |
| E. | collecting duct |
| Answer» D. distal tubule | |
| 443. |
Anti-diuretic hormone controls the concentration of urine, |
| A. | and can concentrate urine to up to 2500mosm/kg H??? H2O |
| B. | in its absence, the collecting duct is impermeable to water |
| C. | causing the ultimate resorption of up to 99.7% of the filtrate |
| D. | by causing upregulation of aquaporin-1 channels |
| E. | collecting duct |
| Answer» D. by causing upregulation of aquaporin-1 channels | |
| 444. |
At which site(s) is potassium ion secreted? |
| A. | distal tubule and collecting duct |
| B. | proximal tubule and distal tubule |
| C. | think limb of loop of Henle only |
| D. | thin limb and thick limb of loop of Henle |
| E. | none of the above |
| Answer» B. proximal tubule and distal tubule | |
| 445. |
Ethanol s action as a diuretic occurs by: |
| A. | inhibition of vasopressin secretion |
| B. | inhibition of the action of vasopressin on the collecting duct |
| C. | production of an osmotic diuresis |
| D. | decreasing tubular reabsorption of Na and increasing GFR |
| E. | inhibition of the Na+ -K+ -Cl- cotransporter in the medullary thick ascending limb of the loop of Henle |
| Answer» C. production of an osmotic diuresis | |
| 446. |
Vasopressin acts as the: |
| A. | proximal convoluted tubule |
| B. | loop of Henle |
| C. | distal convoluted tubule |
| D. | cortical portion of the collecting duct |
| E. | medullary portion of the collecting duct |
| Answer» E. medullary portion of the collecting duct | |
| 447. |
Gamma amino butyric acid: |
| A. | is an excitatory mediator in the brain |
| B. | is formed by decarboxylation of glutamate |
| C. | acts at three different classes of GABA receptors |
| D. | is mostly secreted unchanged in the urine |
| E. | is the main mediator in glutamate |
| Answer» C. acts at three different classes of GABA receptors | |
| 448. |
At which site does chlorthiazide act? |
| A. | proximal tubule |
| B. | thin limb of loop of Henle |
| C. | thick limb of loop of Henle |
| D. | distal tubule |
| E. | collecting duct |
| Answer» E. collecting duct | |
| 449. |
With respect to GFR: |
| A. | clearance of p-amino hippuric acid is used to determine GFR |
| B. | inulin cannot be used to measure GFR |
| C. | GFR is usually reduced in ureteric obstruction |
| D. | filtration pressure changes with change in blood pressure |
| E. | contraction of mesangial cells increases GFR |
| Answer» D. filtration pressure changes with change in blood pressure | |
| 450. |
Regarding the control of GFR: |
| A. | increasing ANP causes contraction of mesangial cells |
| B. | glomerular cap are less permeable than skeletal |
| C. | oedema of kidney causes increase in renal intent po???? |
| D. | efferent arterioles have low reninlard |
| E. | hypoproteinaemia increases GFR |
| Answer» D. efferent arterioles have low reninlard | |