On the heart, the impact of adrenaline is all of these except that

Correct Answer: C

Rationale: Adrenaline (epinephrine) increases heart rate (chronotropy), contraction force (inotropy), and oxygen demand via β-adrenergic stimulation. However, it increases myocardial irritability (risk of arrhythmias), not decreases it, making C the exception.

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.

Correct Answer: D

Rationale: Capillaries are microscopic (A), exchange sites (B), and fed by arterioles (C), but blood flow is slow (D is false, ~0.3 mm/s) to allow exchange.