The blood transports various substances in the body. A healthy adult body contains 5 to 6 litres of blood. Blood consists of two parts: plasma and cells suspended in it.
Plasma consists of water and dissolved or suspended substances. These substances include:
- Chemical substances such as hormones
- Waste materials such as urea
There are three types of blood cells. These are:
- Erythrocytes: Erythrocytes or Red Blood Cells (RBCs) transport oxygen between the lungs and tissues of the body. RBCs also transport a small amount of carbon dioxide from tissues to the lungs.
- Leukocytes: Leukocytes or White Blood Cells (WBCs) fight microbes and other foreign bodies that enter the body. There are many types of leukocytes which perform different protective functions.
- Thrombocytes: Thrombocytes or Platelets are small cell fragments which play an important role in the clotting of blood.They stop bleeding by clumping and clotting blood vessel injuries.
Next: Circulatory sysetm