Part 2: Human Excretory System – Kidney, Nephron, Renal Circulation

Q1. The functional unit of the kidney is:

a) Glomerulus
b) Nephron
c) Loop of Henle
d) Malpighian body

Answer: b) Nephron

Explanation:

(a) Glomerulus – part of nephron, not full unit.
✅ (b) Nephron – structural & functional unit of kidney.
(c) Loop of Henle – segment of nephron.
(d) Malpighian body – includes Bowman’s capsule + glomerulus, but not complete nephron.

Q2. Which structure collects urine from the nephrons?

a) Collecting duct
b) Ureter
c) Renal pelvis
d) Urethra

Answer: a) Collecting duct

Explanation:

✅ (a) Collecting duct – receives filtrate from nephrons.
(b) Ureter – drains urine from renal pelvis to bladder.
(c) Renal pelvis – funnel-shaped cavity.
(d) Urethra – passage for urine excretion.

Q3. The renal cortex contains:

a) Glomeruli and convoluted tubules
b) Loops of Henle
c) Collecting ducts
d) Papillae

Answer: a) Glomeruli and convoluted tubules

Explanation:

✅ (a) Cortex has glomeruli, proximal & distal convoluted tubules.
(b) Loops of Henle – mainly in medulla.
(c) Collecting ducts – in medulla.
(d) Papillae – in medulla.

Q4. Which blood vessel enters the glomerulus?

a) Afferent arteriole
b) Efferent arteriole
c) Peritubular capillary
d) Renal vein

Answer: a) Afferent arteriole

Explanation:

✅ (a) Afferent arteriole – brings blood into glomerulus.
(b) Efferent arteriole – carries blood away.
(c) Peritubular capillaries – around tubules.
(d) Renal vein – drains filtered blood.

Q5. Which part of nephron is most important for selective reabsorption?

a) Bowman’s capsule
b) Loop of Henle
c) Proximal convoluted tubule
d) Distal convoluted tubule

Answer: c) Proximal convoluted tubule

Explanation:

(a) Bowman’s capsule – ultrafiltration, not reabsorption.
(b) Loop of Henle – concentration gradient.
✅ (c) PCT – maximum reabsorption (glucose, amino acids, NaCl, water).
(d) DCT – minor reabsorption and secretion.

Q6. Vasa recta is associated with:

a) Cortical nephrons
b) Juxtamedullary nephrons
c) Both types of nephrons
d) None

Answer: b) Juxtamedullary nephrons

Explanation:

(a) Cortical – no vasa recta.
✅ (b) Juxtamedullary – long loops of Henle with vasa recta.
(c) Both – wrong.
(d) None – wrong.

Q7. Juxtaglomerular cells secrete:

a) Aldosterone
b) Renin
c) ADH
d) Angiotensin II

Answer: b) Renin

Explanation:

(a) Aldosterone – adrenal cortex.
✅ (b) JG cells secrete renin (enzyme).
(c) ADH – posterior pituitary.
(d) Angiotensin II – formed in blood, not secreted directly.

Q8. The glomerular filtration rate (GFR) in a healthy adult is about:

a) 125 ml/min
b) 250 ml/min
c) 500 ml/min
d) 1000 ml/min

Answer: a) 125 ml/min

Explanation:

✅ (a) Normal GFR = ~125 ml/min (≈180 L/day).
(b), (c), (d) – too high.

Q9. Bowman’s capsule is associated with:

a) Loop of Henle
b) Collecting duct
c) Glomerulus
d) Vasa recta

Answer: c) Glomerulus

Explanation:

(a) Loop of Henle – medullary.
(b) Collecting duct – not directly connected.
✅ (c) Bowman’s capsule encloses glomerulus.
(d) Vasa recta – associated with loop of Henle.

Q10. Which part of nephron helps in maintaining medullary concentration gradient?

a) PCT
b) Loop of Henle
c) Bowman’s capsule
d) DCT

Answer: b) Loop of Henle

Explanation:

(a) PCT – reabsorption, not gradient.
✅ (b) Loop of Henle – countercurrent mechanism.
(c) Bowman’s capsule – filtration.
(d) DCT – secretion/reabsorption, not gradient.

Q11. Which artery supplies blood to kidneys?

a) Hepatic artery
b) Renal artery
c) Pulmonary artery
d) Coronary artery

Answer: b) Renal artery

Explanation:

(a) Hepatic – liver.
✅ (b) Renal artery – supplies kidneys.
(c) Pulmonary – lungs.
(d) Coronary – heart.

Q12. Which vein carries blood away from kidney?

a) Jugular vein
b) Renal vein
c) Hepatic vein
d) Pulmonary vein

Answer: b) Renal vein

Explanation:

(a) Jugular – drains head.
✅ (b) Renal vein – drains filtered blood.
(c) Hepatic – drains liver.
(d) Pulmonary – drains lungs to heart.

Q13. Which region of kidney contains renal pyramids?

a) Cortex
b) Medulla
c) Pelvis
d) Hilum

Answer: b) Medulla

Explanation:

(a) Cortex – outer region.
✅ (b) Medulla – has pyramids.
(c) Pelvis – funnel-shaped cavity.
(d) Hilum – entry/exit point.

Q14. Which structure connects kidney to urinary bladder?

a) Urethra
b) Collecting duct
c) Ureter
d) Renal pelvis

Answer: c) Ureter

Explanation:

(a) Urethra – exits bladder.
(b) Collecting duct – drains nephrons.
✅ (c) Ureter – connects kidney to bladder.
(d) Renal pelvis – leads to ureter.

Q15. Human kidneys are located between vertebrae:

a) C1–C3
b) T1–T3
c) T12–L3
d) L5–S1

Answer: c) T12–L3

Explanation:

(a), (b), (d) – wrong levels.
✅ (c) Kidneys located between T12–L3.

Q16. Which structure of nephron is lined by podocytes?

a) PCT
b) DCT
c) Bowman’s capsule
d) Loop of Henle

Answer: c) Bowman’s capsule

Explanation:

(a) PCT – cuboidal epithelium with brush border.
(b) DCT – cuboidal.
✅ (c) Bowman’s capsule – podocytes form filtration slits.
(d) Loop of Henle – squamous epithelium.

Q17. In cortical nephrons, the loop of Henle:

a) Extends deep into medulla
b) Is very short
c) Is absent
d) Is replaced by vasa recta

Answer: b) Is very short

Explanation:

(a) Wrong – deep loop in juxtamedullary nephron.
✅ (b) Cortical nephron – short loop.
(c) Wrong – not absent.
(d) Wrong – vasa recta only in juxtamedullary.

Q18. How many kidneys are present in a normal human adult?

a) 1
b) 2
c) 3
d) 4

Answer: b) 2

Explanation:

✅ (b) Humans have 2 kidneys.
(a), (c), (d) – abnormal conditions.

Q19. Urine from collecting ducts is first received by:

a) Renal pelvis
b) Ureter
c) Minor calyces
d) Urethra

Answer: c) Minor calyces

Explanation:

(a) Renal pelvis – later stage.
(b) Ureter – after pelvis.
✅ (c) Collecting ducts → minor calyces.
(d) Urethra – final passage.

Q20. Which part of nephron is located in medulla?

a) PCT
b) Loop of Henle
c) Bowman’s capsule
d) DCT

Answer: b) Loop of Henle

Explanation:

(a), (c), (d) – cortical region.
✅ (b) Loop of Henle – medullary.

Q21. The glomerular capillaries are supplied by:

a) Efferent arteriole
b) Afferent arteriole
c) Renal vein
d) Peritubular capillary

Answer: b) Afferent arteriole

Explanation:

(a) Efferent – carries blood away.
✅ (b) Afferent – brings blood in.
(c) Renal vein – drains kidney.
(d) Peritubular capillary – after glomerulus.

Q22. Bowman’s capsule + Glomerulus together are called:

a) Malpighian tubule
b) Malpighian body
c) Henle’s loop
d) Vasa recta

Answer: b) Malpighian body

Explanation:

(a) Malpighian tubule – insects.
✅ (b) Malpighian body – glomerulus + Bowman’s capsule.
(c) Henle’s loop – nephron part.
(d) Vasa recta – capillary.

Q23. Which of the following lies at the hilum of kidney?

a) Renal pelvis, renal artery, renal vein, ureter
b) Bowman’s capsule
c) Glomerulus
d) PCT

Answer: a) Renal pelvis, renal artery, renal vein, ureter

Explanation:

✅ (a) Hilum – entry/exit site for blood vessels and ureter.
(b), (c), (d) – inside kidney, not hilum.

Q24. Which type of nephron is more abundant in human kidneys?

a) Cortical nephron
b) Juxtamedullary nephron
c) Both equal
d) None

Answer: a) Cortical nephron

Explanation:

✅ (a) Cortical nephrons – 85% of total.
(b) Juxtamedullary – 15%.
(c), (d) – wrong.

Q25. Which part of nephron is directly connected to Bowman’s capsule?

a) Loop of Henle
b) PCT
c) DCT
d) Collecting duct

Answer: b) PCT

Explanation:

(a) Loop of Henle – after PCT.
✅ (b) Bowman’s capsule → PCT.
(c) DCT – after loop of Henle.
(d) Collecting duct – later.

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Part 2: Human Excretory System – Kidney, Nephron, Renal Circulation