What is the primary function of blood platelets?

The primary function of blood platelets is haemostasis, which is the process that prevents and controls bleeding. When a blood vessel is injured, platelets rapidly adhere to the exposed site and each other, forming a temporary plug to seal the breach. This initial response is crucial in stopping blood loss and is part of a complex cascade of events leading to the formation of a stable blood clot.

Haemostasis also involves the activation of the coagulation cascade, where various clotting factors are triggered, ultimately leading to the conversion of fibrinogen to fibrin, which reinforces the platelet plug. Thus, while clot formation is a critical aspect of the process, it is the role of platelets in initiating and facilitating haemostasis that is essential for maintaining vascular integrity and preventing excessive bleeding.

The other options relate to important physiological functions, but they do not encompass the primary role of platelets. Transportation of oxygen is mainly performed by red blood cells, while the production of antibodies is a function of the immune system. Although clot formation is part of the broader haemostasis process, the term haemostasis more comprehensively describes the overall function of platelets in managing bleeding.