Define artherosclerosis.

Correct Answer: A

Rationale: Atherosclerosis is the hardening and narrowing of arterial walls (A) due to plaque buildup. It doesn’t harden the heart (B), destroy cells (C), or solely inflame walls (D; inflammation is a factor, not the definition).

Correct Answer: C

Rationale: The tunica interna (C), or intima, is the innermost layer with endothelium and basement membrane. Arterioles (A) are vessels, externa (B) is outer, and media (D) is muscular.

Correct Answer: C

Rationale: Per Poiseuille’s law, decreased diameter increases resistance (C, ∝ 1/r⁴), raising BP if flow is constant. A, B, D mismatch resistance-BP relationship.

Correct Answer: A

Rationale: Pulse is the arterial wall’s expansion and recoil (A) with each heartbeat. B is the cause, C is systolic pressure, D is diastolic, not the pulse itself.

Correct Answer: C

Rationale: The foramen ovale (C) is the fetal atrial opening, shunting blood from right to left atrium to bypass lungs. Ductus venosus (A) shunts liver, ductus arteriosus (B) lungs, circle of Willis (D) is cerebral.