Physiology MCQs
Physiology MCQs help medical and dental students develop a thorough understanding of the body's functional mechanisms. These multiple-choice questions focus on various systems such as cardiovascular, respiratory, renal, digestive, endocrine, and neurophysiology. Practicing these MCQs enhances knowledge retention and exam performance in tests like MDCAT, NTS, USMLE, and FCPS. Whether you're preparing for academic exams or professional licensure, these quizzes provide a solid framework for mastering the dynamic processes of the human body.
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.
Q: The volume of air remaining in lungs after maximal expiration
A) Tidal volume
B) Inspiratory reserve
C) Residual volume
D) Vital capacity
✅ Correct Answer: C
Explanation: Residual volume cannot be exhaled and keeps alveoli from collapsing.
Q: Thyroid hormones primarily affect
A) Growth and metabolism
B) Immune function
C) Vision and hearing
D) Blood clotting
✅ Correct Answer: A
Explanation: T3 and T4 regulate basal metabolic rate and promote development and growth.
Q: The part of the nephron responsible for bulk reabsorption
A) Distal tubule
B) Proximal tubule
C) Loop of Henle
D) Collecting duct
✅ Correct Answer: B
Explanation: Proximal tubule reabsorbs about 65% of filtered sodium and water.
Q: Cerebrospinal fluid is produced by
A) Pituitary gland
B) Arachnoid granulations
C) Cerebral cortex
D) Choroid plexus
✅ Correct Answer: D
Explanation: The choroid plexus in ventricles secretes cerebrospinal fluid.
Q: The hormone regulating circadian rhythm
A) Insulin
B) Estrogen
C) Melatonin
D) Cortisol
✅ Correct Answer: C
Explanation: Melatonin, secreted by the pineal gland, helps synchronize sleep-wake cycles.