Physiology is one of the most important subjects for NEET PG because it forms the conceptual base for Medicine, Pathology, Pharmacology, and many clinical subjects. In NEET PG, physiology questions are usually concept-based rather than memorisation-based, and they often test mechanisms, applied clinical scenarios, graphs, ECGs, spirometry, neuromuscular physiology, renal function, endocrinology, and cardiovascular regulation. The following 20 important questions are prepared in a NEET PG-oriented format to help students quickly revise high-yield topics and understand the core concepts required to solve clinical and integrated MCQs.

Here are the Physiology Questions for NEET PG 2026

Q1. The most important determinant of resting membrane potential in neurons is:

A. Sodium permeability
B. Potassium permeability
C. Calcium permeability
D. Chloride permeability

Answer: B. Potassium permeability
At rest, the cell membrane is most permeable to K⁺, so the resting membrane potential lies close to the K⁺ equilibrium potential.

Q2. The upstroke of the action potential in a neuron is due to:

A. K⁺ efflux
B. Na⁺ influx
C. Ca²⁺ efflux
D. Cl⁻ influx

Answer: B. Na⁺ influx
The opening of voltage-gated sodium channels causes rapid depolarisation.

Q3. A patient has myasthenia gravis. The defect is at:

A. Presynaptic Ca²⁺ channel
B. Acetylcholine receptor at the neuromuscular junction
C. Acetylcholinesterase enzyme excess
D. Muscle ryanodine receptor

Answer: B. Acetylcholine receptor at the neuromuscular junction
Myasthenia gravis is due to antibodies against postsynaptic nicotinic acetylcholine receptors.

Q4. The PR interval in ECG represents:

A. Ventricular depolarisation
B. Atrial repolarisation
C. AV nodal conduction time
D. Ventricular repolarisation

Answer: C. AV nodal conduction time
PR interval reflects conduction from the atria through the AV node to the ventricles.

Q5. The second heart sound is produced mainly by:

A. Closure of AV valves
B. Opening of semilunar valves
C. Closure of semilunar valves
D. Rapid ventricular filling

Answer: C. Closure of semilunar valves
S2 is due to the closure of the aortic and pulmonary valves.

Q6. Increased preload causes increased stroke volume due to:

A. Bainbridge reflex
B. Frank-Starling mechanism
C. Baroreceptor reflex
D. Cushing reflex

Answer: B. Frank-Starling mechanism
Increased venous return stretches cardiac muscle fibres and increases the force of contraction.

Q7. In aortic stenosis, the pulse is classically:

A. Pulsus paradoxus
B. Pulsus bisferiens
C. Pulsus parvus et tardus
D. Water-hammer pulse

Answer: C. Pulsus parvus et tardus
Aortic stenosis produces a slow-rising, low-volume pulse.

Q8. The best substance for measuring GFR is:

A. PAH
B. Inulin
C. Urea
D. Creatinine

Answer: B. Inulin
Inulin is freely filtered, not secreted, not reabsorbed, and not metabolised.

Q9. PAH clearance is used to estimate:

A. GFR
B. Renal plasma flow
C. Renal blood flow directly
D. Tubular reabsorption rate

Answer: B. Renal plasma flow
PAH is filtered and secreted, so its clearance approximates effective renal plasma flow.

Q10. Counter-current multiplication in the kidney mainly occurs in:

A. Proximal convoluted tubule
B. Loop of Henle
C. Distal convoluted tubule
D. Collecting duct only

Answer: B. Loop of Henle
The thick ascending limb actively reabsorbs NaCl and is impermeable to water, creating the medullary gradient.

Q11. ADH increases water reabsorption by inserting:

A. Aquaporin-1 in PCT
B. Aquaporin-2 in the collecting duct
C. ENaC in the loop of Henle
D. Na⁺/K⁺ ATPase in the glomerulus

Answer: B. Aquaporin-2 in collecting duct
ADH acts on V2 receptors and inserts aquaporin-2 channels in the collecting duct.

Q12. In obstructive lung disease, spirometry shows:

A. Normal FEV1/FVC
B. Increased FEV1/FVC
C. Decreased FEV1/FVC
D. Increased vital capacity

Answer: C. Decreased FEV1/FVC
FEV1 falls more than FVC in obstructive diseases like asthma and COPD.

Q13. Surfactant is secreted by:

A. Type I pneumocytes
B. Type II pneumocytes
C. Alveolar macrophages
D. Club cells

Answer: B. Type II pneumocytes
Surfactant reduces alveolar surface tension and prevents collapse.

Q14. Pulmonary embolism causes:

A. Physiological shunt
B. Increased dead space ventilation
C. Reduced anatomical dead space
D. Decreased V/Q ratio

Answer: B. Increased dead space ventilation
Ventilation is present, but perfusion is reduced, so the V/Q ratio increases.

Q15. A right shift of the oxygen dissociation curve is caused by:

A. Decreased temperature
B. Decreased PCO₂
C. Increased pH
D. Increased 2,3-BPG

Answer: D. Increased 2,3-BPG
Right shift means decreased Hb affinity for oxygen and increased tissue oxygen unloading.

Q16. Bitemporal hemianopia is caused by a lesion of:

A. Optic nerve
B. Optic chiasma
C. Optic tract
D. Visual cortex

Answer: B. Optic chiasma
Compression of crossing nasal retinal fibres causes loss of temporal visual fields.

Q17. Pain and temperature fibres decussate in:

A. Dorsal column
B. Medulla
C. Anterior white commissure of the spinal cord
D. Internal capsule

Answer: C. Anterior white commissure of the spinal cord
Spinothalamic tract fibres cross within 1–2 spinal segments after entry.

Q18. QAldosterone secretion is mainly stimulated by:

A. ACTH only
B. Angiotensin II and hyperkalemia
C. TSH
D. ANP

Answer: B. Angiotensin II and hyperkalemia
Zona glomerulosa secretes aldosterone in response to angiotensin II and increased serum K⁺.

Q19. Secretin mainly stimulates:

A. Gastric acid secretion
B. Pancreatic bicarbonate secretion
C. Gallbladder contraction
D. Pepsinogen secretion

Answer: B. Pancreatic bicarbonate secretion
Secretin is released from duodenal S cells in response to acid and promotes bicarbonate-rich pancreatic secretion.

Q20. Ovulation is triggered by:

A. FSH surge
B. LH surge
C. Progesterone withdrawal
D. Prolactin surge

Answer: B. LH surge
Mid-cycle LH surge causes ovulation and luteinization of the ruptured follicle.