Friday, October 31, 2008

Blood and its Functions

Meaning of Blood:
Blood is a liquid connective tissue, consists of Plasma (Fluid part) and Cell (Solid part).
Functions of Blood:
  • Blood carry Oxygen and essential nourishment through arteries to every living tissue in the body.
  • Carbon Dioxide and waste products such as urea are removed by the Blood through Veins.
  • It controls body temperature
  • Blood defends against infections
  • Blood is act as a transported of all gases and supply to different part of body.
  • It is also called as the Defence mechanism.It fight against Bacteria & prevent entry of organism

The quantity of Blood:

A healthy man has about 5 Litre of Blood in the body, while a women has about 500ml. less than man.

Constituents of Blood:

There are two main constituents of Blood as Solid or Cellular part"Blood Cell"(consisting of 35%) & Fluid or humoral part called "Plasma"(65%).

Types of Blood Cell:

  1. RBC (Red Blood Corpuscles)
  2. WBC (White Blood Corpuscles)
  3. Platelets


The RBC, which are called Erythrocytes are disc shaped cells. It is visible under a microscope. They have no nucleus. It contain a pigment called Haemoglobin which gives Blood its red color. Haemoglobin is composed of an Iron containing pigment called haema and a protein called globin. In a normal human being the amount of haemoglobin is about 14-15.6 cubic whereas in a woman it is about 11-14 grams. RBCs are produced in the spleen and the bone-marrow at the rate of 1.2 million corpuscles per second. In a life time the Bone marrow creates about half a tone of RBC.

RBC formation of a baby started from the 3rd week of intra-uterin life.

Functions of RBC:

  • Haemoglobin in the RBC picks up Oxygen in the lung tissue by forming a chemical compound with it
  • Oxygen reactions with the products of digestion in order to produce energy
  • Carbon dioxide produced in these reactions and returns to the lungs via the heart where cycle starts again

Value of RBC:
6000 to 11,000


  • The WBC are the White blood corpuscles are the soldier of the body's defend system. They are a little larger than RBC.

Functions of WBC:

Neutrophils are attack the invading bacteria. Lymphocytes are second, they produce anti-bodies. Antibodies protect the body against antigen, foreign substance like Bacteria, viruses, toxins etc.

Value of WBC:

3 million to 5 million

Blood Platelets:

This is a substance which sets off blood clotting, a mechanism that seals tears in Blood Vessels. Blood Platelets live only for a few hours.

Value of Platelets:

450,000 to 1150,000


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