Physician Assistant Scientific Knowledge 3

Question 1

Which pharmacokinetic parameter describes the fraction of an administered drug that reaches systemic circulation unchanged?

Accepted Answer

Bioavailability (F)

Answer

Bioavailability (F) quantifies the proportion of an administered dose that reaches systemic circulation, accounting for first-pass metabolism and absorption.

Question 2

The complement system's membrane attack complex (MAC) is formed by which terminal complement components?

Accepted Answer

C5b-9

Answer

The MAC is assembled from C5b through C9, forming a pore in the target cell membrane that causes osmotic lysis.

Question 3

In a patient with metabolic alkalosis, which compensatory mechanism would you expect?

Accepted Answer

Hypoventilation to retain CO2

Answer

Metabolic alkalosis is compensated by hypoventilation, which retains CO2 and increases carbonic acid to buffer the elevated pH.

Question 4

Which neurotransmitter is released at the neuromuscular junction to initiate skeletal muscle contraction?

Accepted Answer

Acetylcholine

Answer

Acetylcholine is released from motor neuron terminals and binds nicotinic receptors on the motor end plate, triggering muscle depolarization.

Question 5

Which vitamin requires intrinsic factor for absorption and is deficient in pernicious anemia?

Accepted Answer

Vitamin B12 (cobalamin)

Answer

Vitamin B12 binds intrinsic factor produced by gastric parietal cells for absorption in the terminal ileum; autoimmune destruction of parietal cells causes pernicious anemia.

Physician Assistant Practice Test

Physician Assistant Practice Test

Physician Assistant Scientific Knowledge 3