PAX Physiology 3

Question 1

What is the primary function of the kidneys?

Accepted Answer

Filtering blood and producing urine

Answer

The kidneys filter blood to remove waste products, regulate fluid and electrolyte balance, and produce urine for excretion.

Question 2

Which two proteins are primarily responsible for muscle contraction through the sliding filament mechanism?

Accepted Answer

Actin and myosin

Answer

Muscle contraction occurs as actin and myosin filaments slide past each other, powered by ATP energy, shortening the sarcomere.

Question 3

Which ion is essential for triggering skeletal muscle contraction?

Accepted Answer

Calcium (Ca²⁺)

Answer

Calcium ions released from the sarcoplasmic reticulum bind to troponin, exposing myosin-binding sites on actin to initiate contraction.

Question 4

Which type of muscle tissue is found in the walls of internal organs such as the intestines and blood vessels?

Accepted Answer

Smooth muscle

Answer

Smooth muscle is involuntary and non-striated, found in hollow organs such as intestines, blood vessels, and the bladder.

Question 5

What is the basic structural and functional unit of the kidney called?

Accepted Answer

Nephron

Answer

The nephron is the basic functional unit of the kidney responsible for filtering blood, reabsorbing needed substances, and producing urine.

PAX - Pre-Admission Examination Practice Test