The blanket term for reactions that prevent or minimize loss of blood from the vessels if they are injured or ruptured is:

Correct Answer: D

Rationale: Hemostasis is the process of stopping blood loss via vasoconstriction, platelet plugs, and clotting. Homeostasis is broader (body equilibrium), and syneresis is clot shrinkage, not the full process.

Correct Answer: D

Rationale: Vascular resistance is primarily determined by vessel diameter (D), as per Poiseuille’s law (resistance ∝ 1/r⁴), where small changes in radius greatly affect resistance. Length (A) and viscosity (B) contribute but are less dynamic, C is vague, and E (blood pressure) is an outcome, not a determinant.

Correct Answer: D

Rationale: The left atrium receives oxygenated blood from the lungs via the right and left pulmonary veins (D). The coronary sinus (A, B) drains to the right atrium, and the pulmonary trunk (C) is an artery from the right ventricle.

Correct Answer: D

Rationale: Atherosclerosis is caused by endothelial injury (D is false), leading to plaque formation. Smoking (A), insulin-dependent diabetes mellitus (C), and possibly H. pylori (B, via inflammation) are risk factors.

Correct Answer: B

Rationale: Semilunar valves open when ventricular pressure exceeds arterial pressure (B, ~80 mmHg diastolic) during systole. A is the result, C/D don’t open valves.