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: The main function of surfactant in alveoli is to reduce
A) Surface tension
B) Air volume
C) Lung size
D) Oxygen pressure
✅ Correct Answer: A
Explanation: Surfactant prevents alveolar collapse by lowering surface tension in the lungs
Q: The longest phase of the cardiac cycle is
A) Diastole
B) Systole
C) Refractory period
D) Isovolumetric contraction
✅ Correct Answer: A
Explanation: Diastole allows the heart chambers to fill with blood between beats.
Q: The descending loop of Henle is permeable to
A) Glucose
B) Water
C) Urea
D) Sodium
✅ Correct Answer: B
Explanation: Water is reabsorbed here due to the high osmolarity of the surrounding medulla.
Q: The site of fertilization in the female reproductive system is the
A) Ovary
B) Uterus
C) Cervix
D) Fallopian tube
✅ Correct Answer: D
Explanation: The ampulla of the fallopian tube is the typical site for fertilization.
Q: Hemoglobin binds oxygen more readily at
A) High pH
B) High CO₂
C) Low pH
D) High temperature
✅ Correct Answer: A
Explanation: Alkaline conditions favor tighter binding of oxygen to hemoglobin.
Q: The volume of air exchanged during normal breathing is known as
A) Inspiratory reserve
B) Vital capacity
C) Tidal volume
D) Residual volume
✅ Correct Answer: C
Explanation: Tidal volume is about 500 mL in a resting adult.
Q: Vitamin D enhances calcium absorption primarily in the
A) Small intestine
B) Stomach
C) Esophagus
D) Colon
✅ Correct Answer: A
Explanation: Active vitamin D increases calcium uptake from the intestinal lumen into blood.
Q: The phase of gastric secretion activated by food in the stomach is the
A) Cephalic phase
B) Resting phase
C) Gastric phase
D) Intestinal phase
✅ Correct Answer: C
Explanation: The gastric phase is triggered by stomach distension and food presence.
Q: A decrease in oxygen availability triggers increased production of
A) Melatonin
B) Calcitonin
C) Insulin
D) Erythropoietin
✅ Correct Answer: D
Explanation: The kidneys release more erythropoietin in response to hypoxia to produce more RBCs.
Q: The hormone that stimulates milk ejection during breastfeeding is
A) Oxytocin
B) Prolactin
C) Estrogen
D) Testosterone
✅ Correct Answer: A
Explanation: Oxytocin causes contraction of myoepithelial cells in mammary glands.