Haemostatic mechanisms - circulation, Biology

Haemostatic Mechanisms - Circulation

When we accidently get hurt or cut our finger, blood starts flowing but within a few minutes it stops flowing too. Several mechanisms help prevent loss of blood from ruptured blood vessels. Damaged blood vessels constrict and so decrease the blood flow; but the most important mechanism,-however, is the closing of the blood vessel at the site of the injury by formation of a plug or clot which involves the conversion of liquid blood to jelly which prevents further escape of blood. The clotting mechanism or coagulation has been well studied in mammals especially man, as it is of great medical importance.

1661_Haemostatic Mechanisms - Circulation.png

Figure:  Human RBC caught in a mesh of fibrin

Let us try to understand the process. When a section of a blood clot is examined under a microscope, it is found to be composed of a tangled mesh of very delicate fibrils among which are entrapped, as in a net, erythrocytes, leucocytes, and many fragmented platelets. The filaments are composed of fibrin, an insoluble gel form of the protein fibrinogen which is present in the plasma. These filaments may be seen in many places to radiate from centers formed of platelets. If the clot is allowed to stand for a while, it undergoes shrinkage, and as it shrinks, expresses from its meshes a clear, faintly straw coloured fluid, the serum. The serum remains fluid indefinitely; it is quite incapable of clotting, for it contains no fibrinogen. Plasma separated from the blood cells by centrifuging, clots in a way similar to that of whole blood and expresses the clear serum. The clot (coagulation) is white, since it contains no cells, but except for this difference it is identical with that formed in whole blood. The clotting process is essentially, therefore, a phenomenon of the plasma. Lymph also clots, though somewhat more slowly and less firmly than does blood or plasma.

Posted Date: 1/16/2013 12:26:21 AM | Location : United States







Related Discussions:- Haemostatic mechanisms - circulation, Assignment Help, Ask Question on Haemostatic mechanisms - circulation, Get Answer, Expert's Help, Haemostatic mechanisms - circulation Discussions

Write discussion on Haemostatic mechanisms - circulation
Your posts are moderated
Related Questions
what are the characteristics of animal population

Define Proteins as Enzymes? From conception to death, living cells use oxygen and metabolize fuel. Cells synthesize new products, degrade others, and generally are in a state o

Describe how to Analysis and Evaluation of JVP ? 1) Elevated: Any cause producing right ventricular, failure or in pericardial effusion and in constrictive pericardiitis when p

What is reproductive isolation? The Living beings are considered under reproductive isolation when they cannot cross among themselves or if they can cross but cannot generate f

What are the Advantages of Grains Diabetics should have more grains, beans and starchy vegetables every day. Whole-\ grain foods are nutritious and high in fiber, such as whol

Define method Used for Capsular Staining - Anthony Staining Method? Another method used for capsular staining is Anthony staining method, devised by E.E. Anthony in 1931. The m

Which structures of a flowering plant give rise to (a) potatoes, (b) the fleshy scales of an onion?   (a) A potato is a tuber formed at the end of an underground stem (b) O

Define Iodothyronine Deiodinases - functions of selenium in humans? Another group of selenoproteins are the iodothyronine deiodinases essential for the conversion of thyroxine

What is metagenesis? What are the other names of this process? Metagenesis is the type of life cycle in which there are two dissimilar forms of individuals of the same species,

Concerning the thickness of their walls how different are the heart chambers? The ventricle walls are thicker than the atrium walls as ventricles are structures responsible for