Protein that is made by the liver and acted on to become thrombin

Correct Answer: D

Rationale: Prothrombin (D) is liver-made, converted to thrombin.

Correct Answer: D

Rationale: A thrombus (D) is a clot on vessel walls.

Correct Answer: C

Rationale: The myogenic response (C) is smooth muscle contraction in response to stretch, regulating flow. A is skeletal muscle pump, B is cardiac, D is incorrect (endothelins constrict).

Correct Answer: B

Rationale: The left ventricle (B) has the thickest myocardium to pump blood into the high-pressure systemic circuit.

Correct Answer: C

Rationale: Calcium (Ca²⁺, C) is a positive inotrope, enhancing contractility by increasing sarcomere interaction.