Saturday, February 28, 2015

Human Blood

Blood is a connective tissue in liquid form. It is made up of 55% plasma and 45% blood cells.

There are three types of blood cells:
  1. Erythrocyte - Erythrocytes transport oxygen.
  2. Leucocytes - Leucocytes defend the body against diseases.
  3. Platelet - Platelets help in blood clotting.
Blood Clotting

A cut cause a wound on the blood vessel.

Once blood is exposed to air, the platelets release thrombokinase (blood clotting factor), which converts prothrombin (inactive enzyme) into thrombin (active enzyme) in the presence of calcium ions.

Thrombin catalyses the conversion of soluble fibrinogens into insoluble fibrins.

Fibrins form a fibrous network over the wounded area of the blood vessel.

This fibrous network traps the blood cells and forms a blood clot to stop the bleeding.

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