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Blood Clotting

When a blood vessel is cut or damaged the exposed platelets release thrombokinase enzyme. The enzyme neutralizes the anti-clotting factor called heparin. It also activates the conversion of a protein in blood called prothrombin to thrombin in the presence of calcium ions and Vitamin K. Thrombin activates the conversion of a soluble protein fibrinogen to insoluble and fibrous protein called fibrin. Fibrin forms a network of fibers which traps the blood cells forming a clot.

This graphic shows the process of blood clotting


Clotting may also occur inside blood vessels without exposure to the air. This may lead to stroke if it happens in the brain or to cardiac arrest or heart attack if it occurs in coronary vessels. Such blockage prevents food nutrients and oxygen from getting to the tissues served by the vessels and may be fatal.

Importance of Blood Clotting

Blood clotting prevents entry of pathogens into the body through the wound. It also prevents excessive loss of blood following injuries to the skin.