Question

Blood in arteries flows in jerks while that in veins flows continuously. Explain.

Answer 1

Hint: The arteries are responsible for carrying blood away from the heart, to other parts of the body, while veins carry blood from the organs and the rest of the body back to the heart. The process of circulation differs slightly for these vessels.

Complete Answer:
- Blood is pumped from the heart into the arteries by the contraction and relaxation of cardiac muscle. Each time the muscles of the ventricles contract blood is pushed out into the pulmonary artery and the aorta to carry blood to the lungs and into systemic circulation respectively. Because of this continuous contraction and relaxation, the blood that flows through the arteries moves in a jerky manner.
- The Veins collect blood from systemic circulation to bring it back to the heart. Valves are interspersed at regular intervals to prevent any backflow of blood in the veins as most of this circulation is against gravity.
- Flow is maintained by the regular contraction of muscles. This applies to the deep veins in particular, which transport 90% of the blood back to the body. The calf muscle is one of the most involved muscles in this process.
- As we walk, every step keeps the blood flowing smoothly. Superficial veins have a much slower blood flow as they are not surrounded by muscles. Most of the blood they transport is sent to the deep veins.

Note: While the aorta takes oxygenated blood from the heart to be distributed through the arteries to the brain and the rest of the body, the pulmonary artery carries deoxygenated blood from the heart to the lungs for oxygenation.