What is the main function of platelets in blood?

The main function of platelets in blood is to clot blood. Platelets, also known as thrombocytes, play a critical role in hemostasis, which is the process that prevents and stops bleeding. When a blood vessel is injured, platelets are activated and immediately begin to adhere to the site of injury. They stick to the exposed collagen in the damaged tissue and to one another, forming a temporary plug. This aggregation is essential for sealing small breaks in blood vessels.

Platelets also release chemicals that further the clotting process, attract more platelets to the site, and stimulate the healing process. This makes them vital in preventing excessive blood loss during injury or surgery. Other components of the blood, including clotting factors from plasma, work in conjunction with platelets to create a stable clot that effectively stops bleeding.

The other options relate to other blood components: red blood cells (transporting oxygen), white blood cells (fighting infections), and different immune mediators (providing immunity), which are important but serve different functions from that of platelets.