Free Renal Physiology MCQs with Answers

• A. Proximal tubule
• B. Descending limb of loop of Henle
• C. Collecting tubule
• D. Ascending limb of loop of Henle

Explanation: The thick ascending limb is effectively impermeable to water while actively reabsorbing NaCl, making it the diluting segment of the…

• A. Distal tubule
• B. Henle's loop
• C. Proximal tubule
• D. Collecting duct

Explanation: Tubular fluid becomes most concentrated as it descends through the water-permeable limb of Henle into the hyperosmotic medulla, reaching…

• A. Proximal tubule
• B. Loop of Henle
• C. Collecting tubule
• D. Vasa recta

Explanation: ADH inserts aquaporin-2 water channels into principal cells of the late distal tubule and collecting ducts, increasing water permeability…

• A. Mannitol
• B. Glycerol
• C. Urea
• D. All of the above

Explanation: Mannitol, glycerol and urea are poorly reabsorbed osmotic solutes that retain water in the renal tubules, producing osmotic diuresis.

• A. DCT
• B. PCT
• C. Afferent arteriole
• D. Efferent arteriole

Explanation: The macula densa is a specialised group of cells in the distal convoluted tubule, where it forms part of the juxtaglomerular apparatus…

• A. Combining H+ with Cl- to form Hcl
• B. Combining H+ and HCO3- via enzyme carbonic anhydrase
• C. Trapping H+ by acetate
• D. Trapping H+ by NH3+

Explanation: Tubular ammonia accepts secreted H+ to form NH4+, trapping hydrogen ions in the urine and allowing their excretion.

• A. Na is absorbed actively in descending loop of Henle
• B. The filtrate reaching distal convoluted tubule is hypertonic with respect to surroundings
• C. Absorption of water occurs in ascending loop of Henle
• D. 60 to 70% of GFR is absorbed in proximal tubule

Explanation: The proximal tubule normally reabsorbs about 60 to 70% of the filtered sodium and water, and thus of the GFR.

• A. Na+
• B. K+
• C. Glucose
• D. NH4+

Explanation: Medullary hyperosmolarity is produced mainly by accumulation of NaCl in the outer medulla and NaCl plus urea in the inner medulla.

• A. High Na+ in proximal tubule
• B. Low Na+ in proximal tubule
• C. Sympathetic stimulation
• D. Cardiac failure

Explanation: Renin release increases with reduced renal perfusion, sympathetic stimulation and low NaCl delivery to the macula densa.

• A. 100 ml/min
• B. 125 ml/min
• C. 150 ml/min
• D. 175 ml/min

Explanation: The average GFR in a healthy adult is approximately 125 mL/min, equivalent to about 180 litres of filtrate per day.

• A. <70,000 Mol.wt
• B. Bound to plasma protein
• C. Secreted by the tubules
• D. Completely filtered by glomerulus

Explanation: An ideal marker for measuring GFR must be freely and completely filtered by the glomerulus and neither reabsorbed nor secreted by the…

• A. 180 mg / dl
• B. 100 mg/dl
• C. 120 mg/dl
• D. 80 mg/dl

Explanation: The renal threshold for glucose is about 180 mg/dL, the plasma concentration at which glucose first begins to appear in urine.

• A. DCT
• B. PCT
• C. Loop of henle
• D. None

Explanation: The proximal convoluted tubule reabsorbs about 100% of filtered glucose under normal conditions through sodium-glucose cotransporters.

• A. Loop of Henle
• B. Glomerulus
• C. Collecting ducts
• D. Nephron

Explanation: A nephron is the kidney’s functional unit because it performs filtration, reabsorption and secretion.

• A. Bowman's capsule
• B. Proximal convoluted tubule
• C. Distal convoluted tubule
• D. Loop of Henle

Explanation: The proximal convoluted tubule has a prominent brush border of microvilli, which greatly increases its surface area for reabsorption.

• A. Ureter
• B. Major calyx
• C. Minor calyx
• D. Renal pyramid

Explanation: Each renal papilla is the apex of a renal pyramid and projects into a minor calyx. Several minor calyces join to form a major calyx.

• A. Sympathetic stimulation
• B. Fall in the BP
• C. Decrease in the concentration of sodium ions in the distal tubules
• D. Decrease in the concentration of sodium ions in the proximal tubules

Explanation: Renin release is stimulated by sympathetic activity, reduced renal perfusion pressure and reduced NaCl delivery to the macula densa in the…

• A. Dysuria
• B. Oliguria
• C. Nocturia
• D. Plyuria

Explanation: Oliguria means abnormally reduced urine output, commonly defined in adults as less than about 400 mL per day.

• A. Both of the above
• B. Lower filtration pressure
• C. Higher filtration pressure
• D. None

Explanation: Glomerular capillaries maintain a much higher hydrostatic pressure than most systemic capillaries, favouring filtration into Bowman’s…