Describe the structure and function of veins?

Answer 1

Veins carry deoxygenated blood to the heart. To do this they have multiple structural features.

The first feature is the wide lumen. This is because it takes blood back to the heart so a high pressure is not required. It also allows ease of flow.

The second feature is the endothelium that surround the lumen. The endothelium is known as a lining and is a single layer of cells. This reduces friction of the flowing blood.

The third feature of the vein is that it has valves. Valves are very useful as it keeps blood flowing towards the heart and prevents backflow.

The forth feature of the vein is that it has smooth muscle.Smooth muscle can constrict to improve exchange of gas at the alveoli.

The fifth feature of the vein is that it has elastic tissuewhich works as the smooth muscles relaxes to return the vessel to it's orignal size and shape.

Lastly as the previous answer stated: the walls of the vein are thin as there is little muscle.

Answer 2

1) Valves are present in veins to prevent the backflow of blood, so that the flood flows in a one direction

2) The blood flow in veins are slow and smooth. The flow is maintained by the contraction of skeletal muscles which squeeze the veins between them.