How are platelets involved in blood clotting?

Platelets are involved in blood clotting by adhering to damaged blood vessels and forming a plug to stop bleeding.

Platelets, also known as thrombocytes, play a crucial role in the process of haemostasis, which is the body's way of stopping any form of bleeding or haemorrhage. When a blood vessel is damaged, the body responds by activating platelets in the blood. These platelets then adhere to the site of injury, forming a temporary plug to prevent further blood loss.

The process begins with the platelets becoming 'sticky' and adhering to the damaged area of the blood vessel. This is known as platelet adhesion. The platelets then release substances that attract more platelets to the site, causing them to clump together in a process called platelet aggregation. This forms a platelet plug, which serves as a temporary barrier to blood loss.

However, the platelet plug is not stable enough to permanently stop the bleeding. Therefore, the platelets also initiate the coagulation cascade, a series of chemical reactions that result in the formation of a fibrin clot. The fibrin clot is a mesh-like structure that stabilises the platelet plug and provides a more permanent solution to stop the bleeding.

In addition, platelets also release growth factors that help in the repair and regeneration of the damaged blood vessel. This ensures that the blood vessel returns to its normal function once the bleeding has stopped.

In summary, platelets are involved in blood clotting by adhering to the site of injury, aggregating to form a temporary plug, initiating the coagulation cascade to form a stable fibrin clot, and releasing growth factors for repair and regeneration.