Part 5: Regulation of Kidney Function – Hormonal Control

Part 5 (25 MCQs) from Regulation of Kidney Function – Hormonal Control (ADH, Aldosterone, ANF, Renin–Angiotensin System) of Chapter 19: Excretory Products and Their Elimination.

Part 5: Regulation of Kidney Function – Hormonal Control

Q1. Which hormone increases water reabsorption in the collecting ducts?

a) Aldosterone
b) ADH
c) ANF
d) Renin

Answer: b) ADH

Explanation:

• (a) Aldosterone – increases Na+ reabsorption.
• ✅ (b) ADH (vasopressin) increases water permeability via AQP2.
• (c) ANF – promotes water & salt excretion.
• (d) Renin – regulates blood pressure indirectly.

Q2. The renin secreted by juxtaglomerular cells acts on:

a) Angiotensinogen
b) Angiotensin I
c) Aldosterone
d) ADH

Answer: a) Angiotensinogen

Explanation:

• ✅ (a) Renin cleaves angiotensinogen → angiotensin I.
• (b) Angiotensin I – product, not substrate.
• (c) Aldosterone – later in cascade.
• (d) ADH – independent hormone.

Q3. Which enzyme converts angiotensin I into angiotensin II?

a) Renin
b) ACE (Angiotensin-converting enzyme)
c) Aldosterone
d) ADH

Answer: b) ACE

Explanation:

• (a) Renin – angiotensinogen → angiotensin I.
• ✅ (b) ACE – converts I → II.
• (c) Aldosterone – acts after angiotensin II.
• (d) ADH – separate pathway.

Q4. Which of the following is a vasoconstrictor?

a) Angiotensin II
b) Angiotensinogen
c) ANF
d) Renin

Answer: a) Angiotensin II

Explanation:

• ✅ (a) Angiotensin II – strong vasoconstrictor, raises BP.
• (b) Angiotensinogen – precursor.
• (c) ANF – vasodilator.
• (d) Renin – enzyme, not vasoconstrictor.

Q5. Which hormone stimulates sodium reabsorption in DCT?

a) Aldosterone
b) ADH
c) ANF
d) Cortisol

Answer: a) Aldosterone

Explanation:

• ✅ (a) Aldosterone (adrenal cortex) promotes Na+ reabsorption & K+ secretion.
• (b) ADH – water reabsorption.
• (c) ANF – decreases Na+ reabsorption.
• (d) Cortisol – metabolic role, not renal.

Q6. ANF (Atrial Natriuretic Factor) is secreted by:

a) Juxtaglomerular cells
b) Cardiac atrial walls
c) Adrenal cortex
d) Kidney medulla

Answer: b) Cardiac atrial walls

Explanation:

• (a) JG cells – renin.
• ✅ (b) Atria of heart – release ANF when BP is high.
• (c) Adrenal cortex – aldosterone.
• (d) Kidney medulla – not ANF.

Q7. The function of ANF is to:

a) Increase BP
b) Decrease BP
c) Increase Na+ reabsorption
d) Increase ADH secretion

Answer: b) Decrease BP

Explanation:

• (a) Wrong – opposite.
• ✅ (b) ANF → vasodilation + Na+ excretion → lowers BP.
• (c) Opposite action.
• (d) Decreases ADH indirectly.

Q8. Which hormone is called vasopressin?

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

Answer: b) ADH

Explanation:

• (a) Aldosterone – mineralocorticoid.
• ✅ (b) ADH = vasopressin → vasoconstriction + water retention.
• (c) Renin – enzyme.
• (d) Angiotensin II – different peptide.

Q9. Which hormone is secreted from adrenal cortex (zona glomerulosa)?

a) Aldosterone
b) Cortisol
c) Epinephrine
d) ADH

Answer: a) Aldosterone

Explanation:

• ✅ (a) Aldosterone – mineralocorticoid from adrenal cortex.
• (b) Cortisol – from adrenal cortex but zona fasciculata.
• (c) Epinephrine – adrenal medulla.
• (d) ADH – posterior pituitary.

Q10. Angiotensin II stimulates:

a) ADH release
b) Aldosterone secretion
c) Thirst
d) All of the above

Answer: d) All of the above

Explanation:

• (a) Stimulates ADH release.
• (b) Stimulates adrenal cortex → aldosterone.
• (c) Stimulates thirst center.
• ✅ (d) All correct.

Q11. ADH deficiency leads to:

a) Diabetes mellitus
b) Diabetes insipidus
c) Hypertension
d) Uremia

Answer: b) Diabetes insipidus

Explanation:

• (a) Diabetes mellitus – insulin deficiency.
• ✅ (b) ADH deficiency → polyuria (dilute urine).
• (c) Hypertension – excess ADH.
• (d) Uremia – renal failure.

Q12. The renin–angiotensin system primarily regulates:

a) Blood glucose
b) Blood pressure
c) Body temperature
d) Immune response

Answer: b) Blood pressure

Explanation:

• ✅ (b) Main role = regulate BP and GFR.
• Others – unrelated.

Q13. Which hormone reduces sodium reabsorption in kidneys?

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

Answer: b) ANF

Explanation:

• (a) Aldosterone – increases Na+ reabsorption.
• ✅ (b) ANF – promotes Na+ excretion.
• (c) ADH – water only.
• (d) Angiotensin II – promotes Na+ reabsorption indirectly.

Q14. What stimulates release of renin?

a) High blood pressure
b) Low blood pressure
c) High Na+ concentration
d) High blood volume

Answer: b) Low blood pressure

Explanation:

• (a), (c), (d) – inhibit renin.
• ✅ (b) Renin is secreted when BP or Na+ falls.

Q15. Which hormone acts on DCT and collecting duct for water reabsorption?

a) Aldosterone
b) ADH
c) ANF
d) Cortisol

Answer: b) ADH

Explanation:

• ✅ (b) ADH → water channels (AQP2) in collecting duct.
• (a) Aldosterone → Na+, not direct water.
• (c) ANF – opposite effect.
• (d) Cortisol – not renal.

Q16. Aldosterone deficiency may cause:

a) Hypertension
b) Dehydration and hypotension
c) Increased sodium retention
d) Increased blood volume

Answer: b) Dehydration and hypotension

Explanation:

• (a) Hypertension – due to excess aldosterone.
• ✅ (b) Deficiency → Na+ loss → water loss → hypotension.
• (c), (d) – opposite.

Q17. ADH release is stimulated by:

a) Low osmolarity
b) High osmolarity
c) Low blood volume
d) Both b and c

Answer: d) Both b and c

Explanation:

• (a) Low osmolarity – inhibits ADH.
• ✅ (d) High osmolarity & low volume stimulate ADH.

Q18. Which hormone is antagonistic to RAAS (Renin-Angiotensin-Aldosterone System)?

a) ADH
b) ANF
c) Cortisol
d) Glucagon

Answer: b) ANF

Explanation:

• ✅ (b) ANF opposes RAAS, lowers BP & Na+ reabsorption.

Q19. Angiotensin II increases BP by:

a) Vasoconstriction
b) Stimulating aldosterone
c) Stimulating ADH
d) All of these

Answer: d) All of these

Explanation:

• ✅ (d) All effects together raise BP.

Q20. Site of ADH synthesis is:

a) Posterior pituitary
b) Hypothalamus
c) Adrenal cortex
d) Kidney

Answer: b) Hypothalamus

Explanation:

• ✅ (b) ADH synthesized in hypothalamus (supraoptic & paraventricular nuclei), released from posterior pituitary.

Q21. ANF secretion is stimulated by:

a) Increased atrial stretch (high BP)
b) Low BP
c) High ADH levels
d) Low blood osmolarity

Answer: a) Increased atrial stretch (high BP)

Explanation:

• ✅ (a) Atria stretch when BP rises → ANF release.

Q22. Excess aldosterone secretion leads to:

a) Hyponatremia
b) Hypernatremia and hypertension
c) Hypotension
d) Increased urine output

Answer: b) Hypernatremia and hypertension

Explanation:

• ✅ (b) Na+ retention → water retention → hypertension.

Q23. ADH mainly acts on which part of nephron?

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

Answer: c) DCT and collecting duct

Explanation:

• ✅ (c) ADH → increases water reabsorption in distal parts.

Q24. Which hormone’s secretion is inhibited by ANF?

a) ADH
b) Aldosterone
c) Renin
d) All of the above

Answer: d) All of the above

Explanation:

• ✅ (d) ANF lowers BP by inhibiting ADH, aldosterone, and renin secretion.

Q25. The overall effect of RAAS is:

a) Decrease blood pressure
b) Increase blood pressure
c) Increase urine volume
d) Increase ANF

Answer: b) Increase blood pressure

Explanation:

• ✅ (b) RAAS increases Na+ & water retention + vasoconstriction → ↑ BP.

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