Physiology MCQs
Physiology MCQs help medical and dental students master body functions across cardiovascular, respiratory, renal, digestive, endocrine, and neurophysiology systems. Ideal for MDCAT, NTS, USMLE, and FCPS, these quizzes boost retention and exam success.
Q: Aldosterone acts primarily on the
A) Proximal tubule
B) Collecting duct
C) Distal tubule
D) Loop of Henle
✅ Correct Answer: B
Explanation: Aldosterone promotes sodium reabsorption and potassium excretion in the collecting ducts.
Q: Muscle fatigue during prolonged activity is caused by
A) Lactic acid buildup
B) ATP surplus
C) Oxygen surplus
D) Decreased ADP
✅ Correct Answer: A
Explanation: Lactic acid accumulation reduces pH, impairing muscle contraction.
Q: The neurotransmitter released by sympathetic postganglionic neurons
A) Norepinephrine
B) Serotonin
C) Acetylcholine
D) Dopamine
✅ Correct Answer: A
Explanation: Most postganglionic sympathetic fibers release norepinephrine to target organs.
Q: Hyperventilation leads to
A) Metabolic acidosis
B) Respiratory alkalosis
C) Respiratory acidosis
D) Metabolic alkalosis
✅ Correct Answer: B
Explanation: Excessive breathing removes too much CO₂, increasing blood pH.
Q: The hormone that promotes glycogen breakdown
A) Glucagon
B) Prolactin
C) Aldosterone
D) Insulin
✅ Correct Answer: A
Explanation: Glucagon stimulates glycogenolysis in the liver to raise blood glucose.