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: Contraction of skeletal muscle is initiated by
A) Serotonin
B) Acetylcholine
C) Dopamine
D) GABA
✅ Correct Answer: B
Explanation: Acetylcholine released at neuromuscular junction binds to receptors, triggering muscle contraction.
Q: The primary pacemaker of the heart
A) Bundle of His
B) SA node
C) Purkinje fibers
D) AV node
✅ Correct Answer: B
Explanation: SA node generates impulses that initiate the heartbeat rhythm.
Q: Hemoglobin's oxygen affinity increases in
A) Low pH
B) Low temperature
C) High CO₂
D) High 2,3-BPG
✅ Correct Answer: B
Explanation: Low temperature stabilizes the oxygen-bound form of hemoglobin.
Q: Gas exchange in the lungs takes place at
A) Trachea
B) Bronchioles
C) Alveoli
D) Bronchi
✅ Correct Answer: C
Explanation: Alveoli are the thin-walled structures where diffusion of gases occurs.
Q: The resting membrane potential of a typical neuron is about
A) −70 mV
B) 0 mV
C) +30 mV
D) −90 mV
✅ Correct Answer: A
Explanation: A typical neuron maintains a resting potential of −70 mV due to ion distribution.
Q: Parathyroid hormone increases blood calcium levels by
A) Inhibiting bone resorption
B) Enhancing calcium excretion
C) Blocking vitamin D synthesis
D) Stimulating bone resorption
✅ Correct Answer: D
Explanation: PTH increases calcium levels by promoting bone breakdown and calcium release.
Q: Cardiac output is the product of
A) Stroke volume and heart rate
B) Oxygen saturation and heart rate
C) Blood pressure and volume
D) Venous return and resistance
✅ Correct Answer: A
Explanation: Cardiac output equals stroke volume times heart rate.
Q: The primary function of the loop of Henle
A) Water reabsorption
B) Bicarbonate secretion
C) Glucose reabsorption
D) Urea secretion
✅ Correct Answer: A
Explanation: The descending limb of the loop reabsorbs water, concentrating the filtrate.
Q: An action potential is propagated due to
A) Active transport
B) Chemical binding
C) Passive diffusion
D) Ion channel activation
✅ Correct Answer: D
Explanation: Voltage-gated ion channels open and close to propagate the electrical impulse.
Q: The main site of nutrient absorption in the GI tract
A) Stomach
B) Duodenum
C) Small intestine
D) Large intestine
✅ Correct Answer: C
Explanation: The small intestine, particularly jejunum and ileum, is the major site for nutrient absorption.