Question

All of the following contribute to the movement of venous blood EXCEPT A. ventricular systole B. pressure changes in the thorax C. venous valves D. activity of skeletal muscles E. neural control over venoconstriction

Answer 1

Answer:  B. pressure changes in the thorax

Explanation:

The veins are the blood vessels which returns the deoxygenated blood from all the tissues and cells of the body back to the heart. The ventricular systole, venous valves, activity of the skeletal muscles and neural control over venoconstriction all influence the movement of the blood in the venous.

The pressure changes in the thorax occurs due to inspiration and expiration. During the process of inspiration, the diaphragm below the lungs contracts and moves downward while the muscles of the ribs pulls downward. When the size of the thoracic cavity increase the air pressure inside the cavity decreases and vice-versa. The pressure inside the thoracic cavity is not related with the movement of the venous blood as it regulates the exchange of the gases not the blood.