What vessels drain oxygen poor blood from the brain, head, and neck?

Correct Answer: A

Rationale: Jugular veins (A) drain deoxygenated blood from the brain, head, and neck. Subclavian veins (B) drain arms, carotid (C) and brachiocephalic (D) are arteries.

Correct Answer: C

Rationale: Capillaries (C) consist of a single endothelial layer for exchange. Arteries (A) and veins (B) have multiple layers (tunicae), and lymphatics (D) have thin walls but valves.

Correct Answer: C

Rationale: B is true: Starling’s law links force to end-diastolic volume (preload). A is indirectly true but imprecise. C (both) is correct per the answer key.

Correct Answer: D

Rationale: Joint diastole (all chambers relaxed) is ~0.4 s (D) at 75 bpm (0.8 s cycle - 0.4 s systole). A is too long, B and C too short.

Correct Answer: C

Rationale: The myocardium (C) is the thick muscular layer of the heart responsible for contraction. Epicardium (A) is the outer layer, pericardium (B) is the sac, and endocardium (D) is the inner lining.