Question

multiple choice question
when sitting or standing, what is the major force pushing blood from the head towards the heart?

the thoracic (respiratory) pump

the skeletal pump

cardiac suction

gravity

pressure generated by the heart

Explanation:

To determine the major force pushing blood from the head to the heart when sitting/standing:

• The thoracic pump aids venous return via respiratory movements, not specific to head - heart in standing/sitting.
• The skeletal pump relies on muscle contractions (e.g., in legs), not relevant for head blood flow.
• Cardiac suction is not a major mechanism for head - heart blood flow.
• Gravity: When upright, gravity helps pull blood down (from head to heart) as the head is above the heart level.
• Pressure from the heart pushes blood away from the heart (e.g., to the head), not towards the heart from the head.

So gravity is the major force here.

Answer:

D. Gravity