Question

Explain the difference between the different types of vessels in the body, including their characteristics.

Answer 1

There are mainly 5 different types of blood vessels in a human body which are artery, arteriole, capillary, venule and vein.

Function

Arteries carry blood away from the heart to organs and tissues of the body.they widely vary in size. Largest arteries like aorta have special elastic fibres in their vessel wall which help to complement the work of the heart by squeezing blood when heart muscle relaxes. They respond to signals from our nervous system by either constricting or dilating.

Arterioles are smallest arteries in our body which deliver blood to capillaries.They can also costrict and dilate which determine how much of blood enters the capillary.

Capillaries are very tiny vessels which connect arterioles and venules. Capillaries are having very thin walls through which nutrient molecules can pass into body tissues and waste product passes from body tissues to capillary blood.

Venules are very small veins which are fomed by uniting group of capillaries within a tissue. They collect blood from capillaries and pass it on to veins.

Veins are the vessels which are carrying blood towards the heart.Most veins are having valves toprevent backflow of blood.

Structure

The arteries and veins have 3 layers in their wall.

1. Inner layer- tunica intima
2. Middle layer- tunica media (thickest layer in arteries)
3. Outer layer- tunica adventitia (thickest layer in veins)

Tunica media is thicker in the arteries then in veins.

Pressure in the arteries is much higher when compared to that of veins.

Arteries generally have thick walls and narrow lumen while veins have thin walls with large lumen.

Arterioles have the same 3 tunics but thickness of each is reduced. Endothelial lining of tunicaintima is there. Tunica media has only 1-2 smooth muscle layer thickness and tunica externa is very thin.

Capillaries consists of only a single layer of epithelial cells with subepithelial connective tissue and basement membrane.

Walls of venules consist of endothelium, thinmiddle layer of few muscle cell and very thin outer layer.