What occurs during the calf muscle pump at rest?

• A. Venous flow is accomplished through the heart, low hydrostatic pressure and respiratory effects
• B. Blood flow bypasses the heart
• C. Veins fill with arterial blood
• D. Hydrostatic pressure column remains uninterrupted

Answer: (A)

During rest, venous return to the heart is driven by the heart’s pumping action and the respiratory pump, with the venous system operating at relatively low pressure. The calf muscle pump contributes most when the calf muscles actively contract to squeeze the deep veins, but even at rest the blood still travels toward the heart because the heart creates the forward flow and inhalation lowers intrathoracic pressure, helping draw venous blood upward. This combination—flow toward the heart, low venous hydrostatic pressure, and respiratory effects—best describes the resting state of venous return.

The other statements don’t fit because blood in the veins returns to the heart rather than bypassing it; veins carry venous blood, not arterial blood; and the hydrostatic pressure column is not simply uninterrupted—pressure varies with position and breathing.