Furosemide causes a large diuresis because it blocks the Na-K-2Cl cotransporter in the:

Thick ascending limb of the loop of Henle

A man rescued from a smoke-filled room has a pulse oximeter reading of 98% but is confused and has a headache. Why can this reading be misleading?

Standard oximeters count carboxyhaemoglobin as oxyhaemoglobin

Carbon monoxide shifts the dissociation curve to the right

Carbon monoxide dissolves in plasma and displaces oxygen there

Carbon monoxide raises the arterial PaO2 above normal

The kidney can pass urine much more concentrated than plasma. The high osmolality of the renal medulla is created mainly by:

Countercurrent multiplication in the loop of Henle

Glomerular filtration of large amounts of urea

Aldosterone acting on the collecting duct

Countercurrent exchange in the vasa recta

Anatomy, physiology and biochemistry

40 M.Sc Nursing Entrance (AIIMS, LBS, PGIMER, JIPMER) practice questions on Anatomy, physiology and biochemistry, part of Basic Sciences. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Medium
Furosemide causes a large diuresis because it blocks the Na-K-2Cl cotransporter in the:
1. AThick ascending limb of the loop of Henle
2. BCortical collecting duct
3. CEarly distal convoluted tubule
4. DProximal convoluted tubule
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Answer: A · Thick ascending limb of the loop of Henle
The thick ascending limb reabsorbs about 25% of filtered sodium through the Na-K-2Cl cotransporter. Blocking it removes a large share of sodium reabsorption and also disrupts the medullary concentration gradient, so the diuresis is large. More sodium then reaches the collecting duct, where it is exchanged for potassium and hydrogen ions. This explains hypokalaemia and metabolic alkalosis with loop diuretics.
- B: Spironolactone and amiloride act on the collecting duct and spare potassium.
- C: Thiazides block the Na-Cl cotransporter of the early distal tubule.
- D: Acetazolamide acts on the proximal tubule by inhibiting carbonic anhydrase.
Question 2 · Hard
Echocardiography of a man with breathlessness shows a left ventricular end-diastolic volume of 120 mL and an end-systolic volume of 80 mL. What is his ejection fraction?
1. A40%
2. B50%
3. C33%
4. D67%
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Answer: C · 33%
Stroke volume = end-diastolic volume - end-systolic volume = 120 - 80 = 40 mL. Ejection fraction = stroke volume / end-diastolic volume = 40 / 120 = 0.33, or 33%. A normal ejection fraction is about 55-70%, so this shows reduced systolic function, as in heart failure with reduced ejection fraction. Such patients benefit from drugs that improve survival, such as ACE inhibitors or ARNI, beta-blockers and mineralocorticoid antagonists.
- A: 40% treats the stroke volume in mL as a percentage.
- B: 50% divides the stroke volume by the end-systolic volume.
- D: 67% divides the end-systolic volume by the end-diastolic volume.
Question 3 · Medium
A man rescued from a smoke-filled room has a pulse oximeter reading of 98% but is confused and has a headache. Why can this reading be misleading?
1. ACarbon monoxide shifts the dissociation curve to the right
2. BCarbon monoxide dissolves in plasma and displaces oxygen there
3. CStandard oximeters count carboxyhaemoglobin as oxyhaemoglobin
4. DCarbon monoxide raises the arterial PaO2 above normal
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Answer: C · Standard oximeters count carboxyhaemoglobin as oxyhaemoglobin
Carbon monoxide binds haemoglobin about 200-250 times more strongly than oxygen. Carboxyhaemoglobin absorbs red light much like oxyhaemoglobin, so a two-wavelength pulse oximeter reports a falsely normal saturation. CO also shifts the curve to the left, so the oxygen that is carried is released poorly to tissues. Diagnosis needs co-oximetry, and treatment is 100% oxygen, which shortens the CO half-life.
- A: CO shifts the curve to the left, which worsens tissue oxygen release.
- B: CO acts on haemoglobin; the plasma dissolved fraction is not the problem.
- D: PaO2 reflects dissolved oxygen and is usually normal, not raised, in CO poisoning.
Question 4 · Medium
The kidney can pass urine much more concentrated than plasma. The high osmolality of the renal medulla is created mainly by:
1. AGlomerular filtration of large amounts of urea
2. BAldosterone acting on the collecting duct
3. CCountercurrent multiplication in the loop of Henle
4. DCountercurrent exchange in the vasa recta
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Answer: C · Countercurrent multiplication in the loop of Henle
The thick ascending limb pumps sodium chloride out without water, and the descending limb lets water leave, so the loop multiplies a small difference into a gradient up to about 1,200 mOsm/kg. Urea recycling adds to it. The vasa recta act as countercurrent exchangers that preserve the gradient without washing it out. ADH then lets water leave the collecting duct into this hypertonic medulla.
- A: Urea recycling in the medulla helps, but filtration of urea itself does not build the gradient.
- B: Aldosterone controls sodium and potassium exchange, not the medullary gradient.
- D: The vasa recta maintain the gradient but do not create it.
Question 5 · Hard
A patient with chest wall pain breathes 30 times a minute with a tidal volume of 200 mL. Anatomical dead space is 150 mL. What is his alveolar ventilation?
1. A6.0 L/min
2. B1.5 L/min
3. C4.5 L/min
4. D10.5 L/min
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Answer: B · 1.5 L/min
Alveolar ventilation = (tidal volume - dead space) x rate = (200 - 150) x 30 = 50 x 30 = 1,500 mL, or 1.5 L/min. His minute ventilation of 6 L/min looks normal, but most of each breath only fills the conducting airways. A person breathing 12 times a minute at 500 mL has the same minute ventilation yet an alveolar ventilation of 4.2 L/min. This is why rapid shallow breathing leads to carbon dioxide retention and why pain relief and deep breathing are encouraged.
- A: 6.0 L/min is the minute ventilation (200 x 30), not alveolar ventilation.
- C: 4.5 L/min is the dead space ventilation (150 x 30).
- D: 10.5 L/min adds dead space ventilation to minute ventilation.
Question 6 · Hard
A 5-week-old boy with projectile vomiting has Na+ 132, K+ 2.9, Cl- 84 and HCO3- 34 mmol/L, pH 7.52. After a day his urine becomes acidic although he is still alkalotic. Why?
1. AParathyroid hormone release blocks bicarbonate reabsorption
2. BExcess chloride is being excreted by the renal tubules
3. CVomiting causes loss of bicarbonate from the duodenum
4. DVolume depletion drives sodium retention in exchange for H+ and K+
Answer and explanation in LearnFree account
Question 7 · Hard
A non-diabetic 30-year-old staff nurse has repeated episodes of sweating and confusion. During one episode: plasma glucose 38 mg/dL, insulin very high, C-peptide undetectable, sulphonylurea screen negative. The most likely cause is:
1. AAn insulin-secreting tumour of the pancreas
2. BInjection of insulin from an outside source
3. CSecret intake of a sulphonylurea drug
4. DAdrenal insufficiency causing low glucose
Answer and explanation in LearnFree account
Question 8 · Hard
In a glomerulus, capillary hydrostatic pressure is 55 mmHg, Bowman's capsule pressure is 15 mmHg and plasma colloid osmotic pressure is 30 mmHg. What is the net filtration pressure?
1. A25 mmHg
2. B40 mmHg
3. C100 mmHg
4. D10 mmHg
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Question 9 · Hard
A man comes to the hospital with chest pain that began four days ago and has eased. Cardiac troponin I is markedly raised, while CK-MB and myoglobin are within normal limits. Which best explains this pattern?
1. AHaemolysis of the sample in the laboratory
2. BA myocardial infarction within the last two hours
3. CAn injury to skeletal muscle, not to the heart
4. DA myocardial infarction several days ago
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Question 10 · Medium
An adult develops bloating, flatus and watery diarrhoea within two hours of drinking milk. The diarrhoea occurs because the undigested lactose:
1. AActivates chloride secretion in the crypts, as cholera toxin does
2. BHolds water in the gut by osmosis and is fermented by colonic bacteria
3. CIs absorbed intact and then excreted into the bowel by the liver
4. DDamages the small bowel villi and causes malabsorption of fat
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Question 11 · Medium
A patient in diabetic ketoacidosis has a serum potassium of 5.2 mmol/L on admission. Why must potassium be monitored closely once the insulin infusion begins?
1. ACorrecting acidosis releases potassium from the cells
2. BInsulin drives potassium into cells, unmasking a total body deficit
3. CInsulin increases potassium loss in the urine
4. DInsulin destroys potassium-binding plasma proteins
Answer and explanation in LearnFree account
Question 12 · Medium
During a sprint, working muscle produces lactate. In the Cori cycle this lactate is:
1. AExcreted unchanged by the kidneys into the urine
2. BStored in muscle as glycogen for the next sprint
3. CCarried to the liver and converted back to glucose
4. DFully oxidised to carbon dioxide inside the muscle
Answer and explanation in LearnFree account
Question 13 · Medium
A patient on digoxin and furosemide develops nausea, yellow vision and ventricular ectopics. Serum potassium is 2.9 mmol/L. Low potassium makes digoxin toxicity more likely because:
1. ADigoxin is converted to a more toxic form in hypokalaemia
2. BDigoxin binds Na-K-ATPase more readily when potassium is low
3. CLow potassium releases digoxin bound to plasma albumin
4. DLow potassium speeds the renal excretion of digoxin
Answer and explanation in LearnFree account
Question 14 · Hard
A 24-hour urine collection measures 1,440 mL with creatinine 100 mg/dL. Plasma creatinine is 1.0 mg/dL. What is the creatinine clearance?
1. A1,440 mL/min
2. B10 mL/min
3. C144 mL/min
4. D100 mL/min
Answer and explanation in LearnFree account
Question 15 · Medium
Most of the hormone released by the thyroid gland is T4. Most of the T3 that acts on body tissues comes from:
1. ARemoval of one iodine from T4 in peripheral tissues
2. BRelease of T3 from thyroglobulin in the plasma
3. CDirect secretion of T3 by the thyroid follicles
4. DConversion of reverse T3 to T3 in the liver
Answer and explanation in LearnFree account
Question 16 · Medium
When a bedridden patient stands up and blood pressure falls, the carotid sinus baroreceptors respond by:
1. AFiring less, which raises sympathetic outflow and heart rate
2. BFiring less, which raises vagal tone and slows the heart
3. CFiring more, which releases ADH from the posterior pituitary
4. DFiring more, which raises vagal tone and slows the heart
Answer and explanation in LearnFree account
Question 17 · Medium
A 40-year-old man has had profuse watery diarrhoea for two days. Arterial blood gas: pH 7.30, PaCO2 29 mmHg, HCO3- 14 mmol/L. How is this best interpreted?
1. AMetabolic alkalosis with respiratory compensation
2. BRespiratory alkalosis with renal compensation
3. CRespiratory acidosis with renal compensation
4. DMetabolic acidosis with respiratory compensation
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Question 18 · Easy
Anaemia of chronic kidney disease is mainly due to lack of erythropoietin, which in adults is made chiefly by the:
1. AJuxtaglomerular cells of the afferent arteriole
2. BStromal cells of the red bone marrow
3. CPeritubular interstitial cells of the kidney
4. DHepatocytes of the adult liver lobules
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Question 19 · Medium
A 42-year-old has blood pressure 170/104 mmHg, serum potassium 2.8 mmol/L and bicarbonate 32 mmol/L. Plasma renin is suppressed, and there are no Cushingoid features or episodes of palpitation. Excess of which hormone is most likely?
1. AAntidiuretic hormone
2. BAldosterone
3. CAdrenaline
4. DCortisol
Answer and explanation in LearnFree account
Question 20 · Easy
Oxytocin and ADH are released from the posterior pituitary, but they are made in the:
1. AAdrenal medulla
2. BAnterior pituitary
3. CHypothalamus
4. DPineal gland
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Question 21 · Hard
A 66-year-old man with long-standing COPD is clinically stable at his usual level of breathlessness. ABG on room air: pH 7.33, PaCO2 62 mmHg, HCO3- 31 mmol/L, PaO2 58 mmHg. How is this best interpreted?
1. AMetabolic acidosis with respiratory compensation
2. BMixed respiratory and metabolic acidosis
3. CMetabolic alkalosis with respiratory compensation
4. DRespiratory acidosis with renal compensation
Answer and explanation in LearnFree account
Question 22 · Easy
Renin is secreted by juxtaglomerular cells, which are modified smooth muscle cells in the wall of the:
1. AProximal convoluted tubule
2. BCortical collecting duct
3. CEfferent arteriole
4. DAfferent arteriole
Answer and explanation in LearnFree account
Question 23 · Easy
About what share of total serum calcium is in the free, ionised form that is physiologically active?
1. AAbout 25%
2. BAbout 10%
3. CAbout 90%
4. DAbout 50%
Answer and explanation in LearnFree account
Question 24 · Hard
A well, ambulant outpatient's routine sample shows potassium 7.8 mmol/L and calcium 4.1 mg/dL (8.5-10.5). Her ECG is normal and her previous results were normal. The tubes were filled from one syringe, starting with the EDTA tube. What best explains the results?
1. ARhabdomyolysis releasing potassium from muscle
2. BSample contamination with EDTA from the blood count tube
3. CAcute kidney injury causing true hyperkalaemia
4. DHypoparathyroidism with renal tubular failure
Answer and explanation in LearnFree account
Question 25 · Hard
Eight months after a massive postpartum haemorrhage needing six units of blood, a woman reports tiredness, cold intolerance and no return of periods; she could not breastfeed. TSH is 0.2 mIU/L (0.4-4.0) and free T4 is low. The most likely cause is:
1. APostpartum thyroiditis in its toxic phase
2. BSubclinical hypothyroidism developing after pregnancy
3. CAutoimmune primary hypothyroidism
4. DPituitary failure after postpartum haemorrhage
Answer and explanation in LearnFree account

15 more Anatomy, physiology and biochemistry questions

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Anatomy, physiology and biochemistry

Furosemide causes a large diuresis because it blocks the Na-K-2Cl cotransporter in the:

Echocardiography of a man with breathlessness shows a left ventricular end-diastolic volume of 120 mL and an end-systolic volume of 80 mL. What is his ejection fraction?

A man rescued from a smoke-filled room has a pulse oximeter reading of 98% but is confused and has a headache. Why can this reading be misleading?

The kidney can pass urine much more concentrated than plasma. The high osmolality of the renal medulla is created mainly by:

A patient with chest wall pain breathes 30 times a minute with a tidal volume of 200 mL. Anatomical dead space is 150 mL. What is his alveolar ventilation?

A 5-week-old boy with projectile vomiting has Na+ 132, K+ 2.9, Cl- 84 and HCO3- 34 mmol/L, pH 7.52. After a day his urine becomes acidic although he is still alkalotic. Why?

A non-diabetic 30-year-old staff nurse has repeated episodes of sweating and confusion. During one episode: plasma glucose 38 mg/dL, insulin very high, C-peptide undetectable, sulphonylurea screen negative. The most likely cause is:

In a glomerulus, capillary hydrostatic pressure is 55 mmHg, Bowman's capsule pressure is 15 mmHg and plasma colloid osmotic pressure is 30 mmHg. What is the net filtration pressure?

A man comes to the hospital with chest pain that began four days ago and has eased. Cardiac troponin I is markedly raised, while CK-MB and myoglobin are within normal limits. Which best explains this pattern?

An adult develops bloating, flatus and watery diarrhoea within two hours of drinking milk. The diarrhoea occurs because the undigested lactose:

A patient in diabetic ketoacidosis has a serum potassium of 5.2 mmol/L on admission. Why must potassium be monitored closely once the insulin infusion begins?

During a sprint, working muscle produces lactate. In the Cori cycle this lactate is:

A patient on digoxin and furosemide develops nausea, yellow vision and ventricular ectopics. Serum potassium is 2.9 mmol/L. Low potassium makes digoxin toxicity more likely because:

A 24-hour urine collection measures 1,440 mL with creatinine 100 mg/dL. Plasma creatinine is 1.0 mg/dL. What is the creatinine clearance?

Most of the hormone released by the thyroid gland is T4. Most of the T3 that acts on body tissues comes from:

When a bedridden patient stands up and blood pressure falls, the carotid sinus baroreceptors respond by:

A 40-year-old man has had profuse watery diarrhoea for two days. Arterial blood gas: pH 7.30, PaCO2 29 mmHg, HCO3- 14 mmol/L. How is this best interpreted?

Anaemia of chronic kidney disease is mainly due to lack of erythropoietin, which in adults is made chiefly by the:

A 42-year-old has blood pressure 170/104 mmHg, serum potassium 2.8 mmol/L and bicarbonate 32 mmol/L. Plasma renin is suppressed, and there are no Cushingoid features or episodes of palpitation. Excess of which hormone is most likely?

Oxytocin and ADH are released from the posterior pituitary, but they are made in the:

A 66-year-old man with long-standing COPD is clinically stable at his usual level of breathlessness. ABG on room air: pH 7.33, PaCO2 62 mmHg, HCO3- 31 mmol/L, PaO2 58 mmHg. How is this best interpreted?

Renin is secreted by juxtaglomerular cells, which are modified smooth muscle cells in the wall of the:

About what share of total serum calcium is in the free, ionised form that is physiologically active?

A well, ambulant outpatient's routine sample shows potassium 7.8 mmol/L and calcium 4.1 mg/dL (8.5-10.5). Her ECG is normal and her previous results were normal. The tubes were filled from one syringe, starting with the EDTA tube. What best explains the results?

Eight months after a massive postpartum haemorrhage needing six units of blood, a woman reports tiredness, cold intolerance and no return of periods; she could not breastfeed. TSH is 0.2 mIU/L (0.4-4.0) and free T4 is low. The most likely cause is: