What is the main function of platelets in the blood?

The primary function of platelets, also known as thrombocytes, is to play a critical role in hemostasis, which is the process of stopping bleeding. When a blood vessel is injured, platelets quickly gather at the site of the wound to form a temporary plug. They adhere to the exposed collagen in the vessel wall and activate, releasing chemicals that attract more platelets to the site, thus amplifying the response. This aggregation of platelets, along with the formation of fibrin through the coagulation cascade, creates a stable clot that prevents excessive blood loss. In addition, platelets help maintain homeostasis by ensuring that when injury occurs, the body can quickly respond to prevent further complications.

In contrast, other functions listed do not pertain to the role of platelets. Carrying oxygen is primarily the function of red blood cells. Absorbing harmful substances in the blood typically involves the liver and immune system responses. Transporting nutrients to the cells is mainly the responsibility of the plasma and red blood cells, not platelets. Therefore, the main function of platelets is indeed to stop blood loss and maintain homeostasis.