IMAT - International Medical Admissions Human Anatomy and Physiology Questions and Answers

Question 1

Which of the following correctly sequences the path of a deoxygenated red blood cell returning from the systemic circulation to the lungs?

Accepted Answer

Vena cava -> Right atrium -> Right ventricle -> Pulmonary artery

Answer

Deoxygenated blood returns from the body via the vena cavae into the right atrium. It is then pumped into the right ventricle, which contracts to send the blood through the pulmonary artery to the lungs for oxygenation.

Question 2

A patient's blood glucose level rises significantly after a meal. Which of the following represents the correct physiological negative feedback response to this stimulus?

Accepted Answer

The pancreas releases insulin, stimulating cells to take up glucose from the blood.

Answer

High blood glucose stimulates the beta cells of the pancreas to release insulin. Insulin promotes the uptake of glucose by cells and the storage of glucose as glycogen in the liver, which lowers blood glucose levels back to the normal range. This is a classic negative feedback mechanism.

Question 3

The chemical digestion of proteins begins in which organ, and by which primary enzyme?

Accepted Answer

Stomach, by pepsin

Answer

The highly acidic environment of the stomach denatures proteins, and the enzyme pepsin begins their chemical digestion by breaking them down into smaller polypeptides.

Question 4

In the sliding filament model of skeletal muscle contraction, what is the direct role of calcium ions (Ca2+)?

Accepted Answer

To bind to troponin, causing tropomyosin to move and expose actin binding sites.

Answer

When released from the sarcoplasmic reticulum, Ca2+ binds to troponin. This action causes a conformational change that moves tropomyosin away from the myosin-binding sites on the actin filament, allowing cross-bridges to form and contraction to occur.

Question 5

Following the repolarization phase of a neuron's action potential, what is the primary function of the Na+/K+ pump?

Accepted Answer

To restore the resting ion concentration gradients by moving Na+ out and K+ into the cell.

Answer

After an action potential, the ion concentrations of Na+ and K+ are imbalanced. The Na+/K+ pump actively transports 3 Na+ ions out of the cell for every 2 K+ ions it transports in, re-establishing the original concentration gradients necessary for the resting membrane potential.

IMAT - International Medical Admissions Test Practice Test

IMAT - International Medical Admissions Test Practice Test

IMAT - International Medical Admissions Human Anatomy and Physiology Questions and Answers