Hemostasis does not involve:

Correct Answer: D

Rationale: Hemostasis includes vasoconstriction (smooth muscle), platelet adhesion, and clot retraction. The renin-angiotensin system regulates blood pressure, not directly involved in hemostasis.

Correct Answer: D

Rationale: The cardiac cycle is the sequence of mechanical and electrical events between one heartbeat and the next , including systole and diastole (~0.8s at 75 bpm). A is too broad, B is cardiac output, C is ECG-specific, and D is heart sound-specific, not the full cycle.

Correct Answer: C

Rationale: The left ventricle (C) pumps oxygen-rich blood into the aorta for systemic circulation. The left atrium (A) fills the left ventricle, the right atrium (B) receives deoxygenated blood, and the right ventricle (D) pumps to the lungs.

Correct Answer: B

Rationale: The SA node (B) is the natural pacemaker, initiating impulses at 60-100 bpm. The AV node (C) delays, AV bundle (A) conducts, and Purkinje fibers (D) spread the signal.

Correct Answer: C

Rationale: Stroke volume (C) is the volume pumped per contraction (~70 mL). A is end-diastolic volume, B is end-systolic volume, D is cardiac output.