What are the three main types of blood vessels in the body?
Arteries are the vessels which carry blood away from the heart to various
organs of the body. Since the blood emerges from the heart under high
pressure, the arteries have thick, elastic walls.
Veins collect the blood
from different organs and bring it back to the heart. They do not need
thick walls because the blood is no longer under pressure, instead they
have valves that ensure that the blood flows only in one direction.
On reaching an organ or tissue, the artery divides into smaller and
smaller vessels to bring the blood in contact with all the individual cells.
The smallest vessels have walls which are one-cell thick and are called
capillaries. Exchange of material between the blood and surrounding
cells takes place across this thin wall. The capillaries then join together
to form veins that convey the blood away from the organ or tissue.
Arteries are the vessels which carry blood away from the heart to various organs of the body. Since the blood emerges from the heart under high pressure, the arteries have thick, elastic walls.
Veins collect the blood from different organs and bring it back to the heart. They do not need thick walls because the blood is no longer under pressure, instead they have valves that ensure that the blood flows only in one direction.
On reaching an organ or tissue, the artery divides into smaller and smaller vessels to bring the blood in contact with all the individual cells. The smallest vessels have walls which are one-cell thick and are called capillaries. Exchange of material between the blood and surrounding cells takes place across this thin wall. The capillaries then join together to form veins that convey the blood away from the organ or tissue.
