Arterial thrombi are composed of platelets and fibrin to produce a white clot. True False
The correct answer and explanation is:
True
Arterial thrombi are indeed composed primarily of platelets and fibrin, which together form a “white clot.” The formation of arterial thrombi is usually triggered by damage to the blood vessel wall, leading to platelet activation and aggregation. Here’s a more detailed explanation:
When the inner lining of an artery, known as the endothelium, is injured—often due to factors like atherosclerosis or mechanical damage—platelets adhere to the exposed tissue. This is the first step in clot formation. Platelets release various substances, including thromboxane A2, which promote further platelet aggregation and activation. The platelets form a dense plug at the site of injury, but this initial “platelet plug” is not enough to form a stable clot on its own.
The next step in the clotting process involves the activation of the coagulation cascade, which leads to the conversion of fibrinogen into fibrin. Fibrin threads mesh with the platelets, reinforcing the platelet plug and transforming it into a more stable clot. The fibrin component gives the clot its structure and strength. However, in arterial thrombi, platelets play a more prominent role than fibrin. As a result, these thrombi appear white because of the large number of platelets compared to the red blood cells (which are more prominent in venous thrombi).
This is in contrast to venous thrombi, which are rich in red blood cells and are often referred to as “red clots.” These typically form in veins under conditions of stasis, where blood flow is slower, allowing red blood cells to become more incorporated into the clot.
In summary, arterial thrombi are indeed composed primarily of platelets and fibrin, and this combination of components creates a white clot, which is characteristic of arterial thrombosis.