Which of the following is not a mechanism that assists venous return?

• A. Respiratory pump
• B. Arterial pressure
• C. Skeletal muscle pump
• D. Venous valves

Answer: (B)

Verified step by step guidance

1. Understand the concept of venous return: Venous return is the process of blood returning to the heart from the body. It is crucial for maintaining blood circulation and is assisted by several mechanisms.
2. Identify the mechanisms that assist venous return: The primary mechanisms include the respiratory pump, skeletal muscle pump, and venous valves.
3. Explain the respiratory pump: During inhalation, the diaphragm moves downward, decreasing thoracic pressure and increasing abdominal pressure, which helps push blood towards the heart.
4. Explain the skeletal muscle pump: As muscles contract, they compress veins, pushing blood through the venous system towards the heart. This is especially important in the limbs.
5. Explain the role of venous valves: These valves prevent backflow of blood, ensuring it moves in one direction towards the heart. Arterial pressure, however, is not a mechanism that assists venous return, as it primarily affects the arterial system, not the venous system.