Powered by Blogger.


Trying to provide all necessary information about IMMUNITY and IMMUNE SYSTEM

Coagulation of blood

Posted by Mumtaz khan Monday, 17 October 2011

Homeostasis refers to stoppage of bleeding.when blood vessels are ruptured or damaged hemostatic response must be quick localised to the region of damage and carefully controlled three basic mechanisms present blood loss viz,
(1) Vascular spasm.
When the blood vessels are damaged the circularly arranged smooth muscles immediately contracts this is referred to as vascular spasm and will reduce blood loss.This is crucial because during this time other homeostatic mechanism get into operation.The vascular spasm is caused by damage to the smooth muscles and reflexes initiated by pain receptors.

(2) Platelet plug formation.
The blood platelets in their original unstimulated state are disc shaped showing two types of granules in their cytoplasm viz., alpha granules and dense granules.
In the first phase of platelet formation,blood platelet come together make a contact and stick to the part of damaged blood vessels.This process is called platelet adhesion.As a result of adhesion,the platelets which were earlier unstimulated now become activated and their charactreistics change drastically.They extend projections which help them to make further contacts with the neighboring platelets and to release  their contents from the granules.This is referred to as platelet release reaction.The liberated ATP will activate the neighboring platelets as well. Serotonin  alongwith a factor called thromboxane causes vasoconstriction.Thus decreasing the bloodflow..The release of ADP will make the platelets more sticky and this stickiness will cause them to adhere to each other. This gathering of platelets for stickiness is referred to as Platelet Aggregation.

(3) Blood clotting.
 Normally blood remains in th liquid state as long as it stays within the blood vessels but if it is withdrawn from the body it gets converted from the fluid state into a gel state.Eventually the gel separates from the liquid and a yellow colored or straw colored liquid which oozes out from blood clot,is called Serum(Serum means plasma clotting proteins). The remaining gel is called a clot consisting of network of insoluble fibers of fibrin in which blood corpuscles get trapped.This process of gel formation is called coagulation or clotting.
    Clotting involves several enzymes and other chemicals known as Clotting factors.Most of these clotting factors are synthesized in the liver and finally released in the blood plasma.There are some clotting factors which is released by blood platelets and some clotting factor (recently accepted)which is released from the damaged tissue cells earlier it was called as Thromboplastin.


Post a Comment