Anatomy and Physiology II Practice Test

Platelets, also known as thrombocytes, play several critical roles in the body, primarily related to hemostasis, which is the process of stopping bleeding. The primary functions of platelets include clotting the blood, repairing damaged blood vessels, and releasing growth factors.

Clotting the blood is a primary function of platelets. When a blood vessel is injured, platelets adhere to the site of injury and aggregate to form a temporary "platelet plug," which is essential in halting blood loss. They release chemical signals that promote further aggregation of more platelets and the formation of a fibrin clot.

In addition to clotting, platelets contribute to the repair of damaged blood vessels. They release various growth factors, such as platelet-derived growth factor (PDGF), which stimulate healing processes in the vascular tissue.

Thus, the function that is NOT associated with platelets is the transportation of oxygen. This role is primarily performed by red blood cells (erythrocytes), which contain hemoglobin that binds to oxygen in the lungs and carries it to the tissues throughout the body.