How blood is preserved without getting coagulated in blood bank?

Answer 1

When there is an injury and blood flows, a mechanism is provided within the body whereby blood loss is prevented. This is termed as the coagulation or clotting of blood.

The actual mechanism of blood coagulation is a complicated one, but the general principles are simple and important. Before clotting, there are some substances which must be present in the blood. They are prothrombin, calcium, fibrinogen and thromboplastin.

Prothrombin, calcium and fibrinogen are all normal constituents of blood. But thromboplastin is released only when there is a damage in a blood vessel or tissue cell the release of thromboplastin from thrombocytes or blood platelets brings about a series of changes or events which finally produces a blood clot.

Normally, prothrombin (protein present in the plasma) as such is inactive, but when acted upon thromboplastin in the presence of calcium is converted to an active substance thrombin.

Thrombin in turn acts on fibrinogen, another plasma protein, to produce an in soluble thread-like substance called fibrin.

The fibrin threads entrap blood cells to form a solid mass, the clot. After sometimes the clot shrinks', and a clear stickle fluid, serum is released, (Serum=plasma-fibrinogen).

The mechanism of clotting can be expressed in a simple formula:

1. Prothrombin + Calcium+thromboplastin = Thrombin (active) (inactive) (from damaged tissue cells and platelets)

2. Thrombin + fibrinogen = Fibrin (fine threads) (inactive)

3. Fibrin + blood cells = CLOT

Certain factors or conditions hasten the clotting of blood, while others retards