Physiology MCQs 2026

The refractory period in cardiac muscle prevents

1. A tetanic contraction of the heart ✓
2. B normal sinus rhythm ✓
3. C atrial contraction ✓
4. D ventricular filling ✓

Normal adult resting heart rate is approximately

1. A 120-160 beats per minute ✓
2. B 30-40 beats per minute ✓
3. C 100-140 beats per minute always ✓
4. D 60-100 beats per minute ✓

The pacemaker of the heart is the

1. A atrioventricular node only ✓
2. B sinoatrial node ✓
3. C bundle of His only ✓
4. D Purkinje fibers only ✓

Oxygen is primarily transported in blood bound to

1. A plasma albumin only ✓
2. B white blood cells ✓
3. C hemoglobin in red blood cells ✓
4. D platelets ✓

Insulin is secreted by

1. A beta cells of the pancreatic islets ✓
2. B alpha cells of pancreas ✓
3. C delta cells only ✓
4. D adrenal cortex ✓

Glucagon acts to

1. A lower blood glucose ✓
2. B increase insulin secretion directly ✓
3. C block renal glucose reabsorption ✓
4. D raise blood glucose by glycogenolysis and gluconeogenesis ✓

The primary function of aldosterone is

1. A water reabsorption via ADH only ✓
2. B calcium absorption in gut only ✓
3. C sodium reabsorption and potassium excretion in the kidney ✓
4. D red blood cell production ✓

Antidiuretic hormone (ADH) increases

1. A sodium excretion only ✓
2. B potassium retention only ✓
3. C glucose filtration ✓
4. D water reabsorption in the collecting duct ✓

The normal pH of arterial blood is approximately

1. A 7.35-7.45 ✓
2. B 6.8-7.0 ✓
3. C 7.6-7.8 ✓
4. D 8.0-8.2 ✓

Surfactant in the lungs reduces

1. A mucus production only ✓
2. B bronchial smooth muscle tone only ✓
3. C pulmonary blood flow ✓
4. D surface tension to prevent alveolar collapse ✓

Gastrointestinal motility is coordinated by the

1. A enteric nervous system and hormones ✓
2. B sympathetic system alone ✓
3. C cerebellum alone ✓
4. D reticular activating system alone ✓

The primary stimulus for erythropoietin release is

1. A hyperglycemia ✓
2. B hypoxia detected by the kidney ✓
3. C hypercalcemia ✓
4. D hypernatremia ✓

Calcium homeostasis is regulated mainly by

1. A insulin and glucagon only ✓
2. B TSH and thyroxine only ✓
3. C ACTH and cortisol only ✓
4. D parathyroid hormone, calcitonin and vitamin D ✓

The action potential in a neuron is propagated along the

1. A dendrites only ✓
2. B axon ✓
3. C cell body only ✓
4. D synaptic cleft only ✓

The neuromuscular junction uses which neurotransmitter

1. A dopamine ✓
2. B acetylcholine ✓
3. C serotonin ✓
4. D GABA ✓

Starling law of the heart states that

1. A heart rate always equals stroke volume ✓
2. B afterload has no effect on output ✓
3. C stroke volume increases with increased venous return (preload) ✓
4. D contractility is fixed ✓

The glomerular filtration rate is primarily autoregulated by

1. A afferent and efferent arteriolar tone ✓
2. B ureter peristalsis ✓
3. C bladder compliance ✓
4. D ADH levels alone ✓

Body temperature is regulated by the

1. A cerebellum ✓
2. B hypothalamus ✓
3. C medulla oblongata only for all thermoregulation ✓
4. D occipital lobe ✓

The Bohr effect describes

1. A increased oxygen binding in acidosis ✓
2. B carbon monoxide binding preference only ✓
3. C chloride shift in platelets ✓
4. D decreased hemoglobin oxygen affinity with increased CO2 and acidity ✓

Renin is secreted by the

1. A adrenal medulla ✓
2. B posterior pituitary ✓
3. C juxtaglomerular cells of the kidney ✓
4. D liver hepatocytes ✓

The Frank-Starling mechanism improves cardiac output during exercise by

1. A decreased heart rate only ✓
2. B decreased preload ✓
3. C increased venous return stretching the ventricle ✓
4. D complete AV block ✓

Primary active transport example in physiology is

1. A sodium-potassium ATPase pump ✓
2. B facilitated diffusion of glucose ✓
3. C simple diffusion of oxygen ✓
4. D osmosis of water ✓

The Haldane effect refers to

1. A oxygen increasing CO2 carrying capacity ✓
2. B nitrogen dissolving in plasma only ✓
3. C deoxygenated hemoglobin carrying more CO2 ✓
4. D chloride binding to hemoglobin only in lungs ✓

Baroreceptors in the carotid sinus respond to

1. A blood glucose levels ✓
2. B changes in arterial blood pressure ✓
3. C partial pressure of oxygen in alveoli only ✓
4. D CSF pressure ✓

The main buffer system in extracellular fluid is

1. A phosphate only ✓
2. B hemoglobin only in plasma ✓
3. C bicarbonate-carbonic acid ✓
4. D protein buffers only without bicarbonate ✓