Blood Coagulation: Definition, Process and Sample Questions

Blood is a vital fluid that circulates throughout our body to maintain its functioning. Considering how important it is, a significant loss of blood in case of any injury might even lead to death. Thus, to prevent excessive blood loss in humans, the mechanism of blood coagulation is initiated. Blood Coagulation is the process of the formation of blood clots, also known as thrombus. In this article, we will learn more about the process of blood coagulation and deep vein thrombosis.

Keyterms: Blood, Blood Coagulation, Deep vein thrombosis, Blood artery, platelets, platelet plug, fibrin, blood vessel

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What is Blood Coagulation?

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Blood Coagulation, otherwise known as clotting, is the process by which a blood clot is formed, with the blood changing from a liquid to a gel, as a semi-solid. It acts as a way to avoid the loss of excessive blood from the body in case the body suffers any injury. After the damage to the endothelium lining of a blood artery, coagulation occurs very immediately. 

When blood is exposed to the subendothelial space, two processes occur - platelet modifications and the exposure of subendothelial tissue factor to plasma factor VII, which results in the production of cross-linked fibrin. Primary hemostasis occurs when platelets instantly form a plug at the site of damage. Additional coagulation, also known as clotting, factors beyond factor VII respond to produce fibrin strands. This reinforces the platelet plug.

Read More: Systolic and Diastolic Blood Pressure

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Process of Blood Coagulation

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The blood clotting mechanism is the process through which a thrombus or clot is created, preventing excess blood from flowing out. Fibrin and platelets combine to form this gel-like substance. The blood clotting process involves several stages that culminate in blood coagulation. Hemostasis (the opposite of haemorrhage) is a process that stops bleeding and aids in the healing of a broken blood vessel by preventing the loss of blood.

• The primary hemostasis is caused by vasoconstriction, which is the body's reaction to damage to the arterial wall. When the vascular walls are damaged, they rapidly reduce blood flow to the diseased region. 
• The platelets then help to stop the bleeding by covering the damaged region. They also initiate a secondary hemostasis process, which results in the formation of a fibrin clot. This causes the release of stored granular contents containing serotonin, ADP, and thromboxane, resulting in increased platelet activation in the blood plasma. 
• Because platelets alone are unable to repair the damage to the artery walls, a blood clot is formed. The development of blood clots is dependent on a number of clotting components that interact with one another in the clotting cascade. Fibrinogen, a soluble plasma protein, is formed as a result of this cascade. 
• Finally, these fibrin proteins bind together to create a clot. White thrombus is referred to as the platelet clots, whereas a red thrombus is formed when red blood cells are also present.

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Deep Vein Thrombosis

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The development of a blood clot in a deep vein, most often in the legs or pelvis, is known as deep vein thrombosis (DVT). Only a small percentage of DVTs occur in the arms. 

Pain, edema, redness, and swollen veins in the afflicted region are common signs of Deep Vein Thrombosis, although some DVTs go unnoticed. The most frequent life-threatening worry with DVT is the possibility of a clot embolizing (detaching from the veins), traveling through the right side of the heart as an embolus, and being stuck in a pulmonary artery that feeds blood to the lungs. Pulmonary embolism is the medical term for this mechanism(PE). The cardiovascular disease of venous thromboembolism includes DVT and PE (VTE).

VTE in two-thirds of cases is presented as DVT alone, and in one-third cases as PE with or without DVT. Post-thrombotic syndrome is the most common long-term DVT consequence, which can include discomfort, swelling, heaviness, itching, and ulceration in extreme instances. In the ten years following a first VTE, around 30% of people have recurrent VTE.

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Diseases Affecting Blood Coagulation

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There are various diseases that affect the mechanism of blood coagulation in humans. These are:

• Willebrand disease, wherein a person has a lesser amount of VWF protein in their body and thus is incapable of forming a platelet plug.
• Hemophilia is another such disorder where some clotting factors are damaged or missing inside a person’s body, affecting their blood coagulation mechanism.

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Things to Remember

• Blood Coagulation, otherwise known as clotting, is the process by which a blood clot is formed, with the blood changing from a liquid to a gel, as a semi-solid. 
• Hemostasis (the opposite of haemorrhage) is a process that stops bleeding and aids in the healing of a broken blood vessel by preventing the loss of blood.
• The development of a blood clot in a deep vein, most often in the legs or pelvis, is known as deep vein thrombosis (DVT).
• Various disorders such as Willebrand disease obstruct the formation of a blood clot. In Willebrand disease, a person has a lesser amount of VWF protein in their body.
• Hemophilia is another such disorder where some clotting factors are damaged or missing inside a person’s body, affecting the blood coagulation mechanism.

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