What is thrombosis and what are the different causes of it?

Introduction to thrombosis:

Thrombosis (or intravascular clotting) refers to the formation of a blood clot inside a blood vessel. The clot so formed inside the blood vessel is known as thrombus.

Normally there is present certain coagulation factors in the blood,such as - Heparin, Fibrin, antithrombin lll ,which prevent the formation of blood clot inside a blood vessel.

But some abnormal conditions cause thrombosis, obstructing the flow of blood through the circulatory system.

When a thrombus occupies more than 75% of the surface area of the lumen of an artery,then it causes reduction in the flow of blood to the tissues, which at last, develop various symptoms.

If the thrombus occupies more than 90% of the surface area of the lumen of an artery then it can result in anorexia.

Blood clot diagram,Image by-en:User:Persian Poet Gal, Source, License-CC BY-SA3.0

Different Causes of thrombosis:

1.Very smooth and silky portion of the blood vessel endothelial lining consists of a single layer of cells . Endothelial lining lies in contact with blood.

If the this smooth and silky portion of the blood vessel namely endothelial lining is damaged by infection or by mechanical obstruction then it causes thrombosis.

2. Arteriosclerosis also causes , thrombosis, because in this condition the endotheliam of the blood vessel becomes rough,and which leads to the formation of the blood clot.

3.Both in turbulence and static blood flow ,there is alternations in the normal axial flow of blood . Because of this reason the platelets aggregates in the endothelium of the blood vessel and leads to the formation of thrombus.

During reduced cardiac action, hypotension,low metabolic rate , slowness of blood flow occurs.

Classification of thrombosis:

There is present two distinct forms of thrombosis,each of which can be presented by several subtypes.

1.Venous thrombosis:

Formation of thrombus inside a vein is known as venous thrombosis. Venous thrombi are usually red in colour and occlusive.

2.Arterial thrombosis:

The formation of thrombus inside a artery is known as arterial thrombosis. Arterial thrombi tend to be white and mural whereas white thrombi are pale and firm.

Formation of a thrombus:

The sequence of events which leads to the formation of a thrombus is known as thrombogenesis. The events in thrombogenesis are:

1.The first step in the process of thrombogenesis is the adherence of platelets to the endothelium of the blood vessel. The mass of platelets grows by adhesion of other platelets as they pass by .

Formation of venous thrombosis

2. In this step the platelets liberate thromboplastin and helps in the activation of coagulation system,thus filaments of fibrin spread out from them on all sides.

Fibrin filaments from one lamellae

meet with filaments from the next lamillae. The lamella of filaments are thus joined together by fibrin filaments.

3. Then in the fibrin network, entanglement of Red Blood cells and White Blood Cells occurs. And finally a solid mass of peculiarly constructed clot called thrombosis is formed.