A healthy 25-year-old man increases his physical activity level, leading to an increase in venous return to the heart. According to the Frank-Starling mechanism, what is the immediate physiological consequence of this increased venous return?

The correct answer to the question "A healthy 25-year-old man increases his physical activity level, leading to an increase in venous return to the heart. According to the Frank-Starling mechanism, what is the immediate physiological consequence of this increased venous return?" is Option B: Increased stroke volume.

The other options — A) Decreased end-diastolic volume, C) Decreased myocardial contractility, D) Increased arterial pressure without change in cardiac output — are incorrect for this USMLE Exam Prep question. As explained above: Increased venous return leads to increased end-diastolic volume, which stretches the cardiac muscle fibers. According to the Frank-Starling mechanism, this increased stretch results in a more forcefu…