During light exercise, which changes occur in the cardiovascular system?

• A. Extensive vasodilation, increased venous return, increased cardiac output
• B. Extensive vasoconstriction, decreased venous return, decreased cardiac output
• C. No change in vascular tone
• D. Vasodilation with no change in cardiac output

Answer: (A)

During light exercise, blood is redirected toward working muscles. Local signals produced by active skeletal muscle cause the arterioles in those muscles to dilate, increasing blood flow to meet the rising oxygen and nutrient demand. This vasodilation in the muscle beds helps deliver more blood where it’s needed, and it tends to lower overall systemic vascular resistance a bit.

To provide that increased flow, venous return to the heart rises. The muscle pump—the rhythmic squeezing of veins by contracting muscles—pushing blood back toward the heart, along with sympathetic venoconstriction, enhances venous return.

With more blood returning, the heart beats more forcefully and often faster, increasing stroke volume and heart rate. The net effect is a higher cardiac output to supply the active muscles with sufficient blood flow.

So, the combination of vasodilation in active muscles, increased venous return, and increased cardiac output best describes what happens during light exercise.