Question

Are arteries and veins living cells?

We know that arteries carry only oxygenated blood and veins carry only deoxygenated blood then how will the veins get oxygen?

Answer 1

Composition of arteries and veins:

1. The walls of arteries and veins are largely composed of living cells arranged in three layers.
2. Tunica intima- It is innermost layer, is a simple squamous epithelium surrounded by connective tissue basement membrane with elastic fibres. The cells are also called endothelial cells.
3. Tunica media- The middle layer, is primarily made up of smooth muscle and thick layer . It changes vessel diameter for regulation of blood flow and blood pressure.
4. Tunica adventitia- Outermost layer, it attach vessels to surrounding tissues.This layer is connective tissue with elastic and collagenous fibres.
5. Hence, all the layers are made up of living cells and tissues.

Supply of oxygen to arteries and veins:

1. There are two ways in which the oxygen is supplied to the cells and tissues of veins and arteries.
2. The two ways are- direct diffusion and through vasa vasorum.
3. Oxygen diffuses readily from the blood plasma into and even through the endothelial cells.
4. In veins and arteries, about the inner 1/3 of the vessel wall is oxygenated by direct diffusion from the blood.
5. The outer 2/3 of the wall gets its oxygen from smaller blood vessels called vasa vasorum that penetrate into the walls of the larger veins and arteries.