Rutgers Anatomy & Physiology II Practice Exam

Platelets are essential components of the blood that play a crucial role in hemostasis, the process of stopping bleeding. One of their significant functions is the release of various substances, including serotonin. When platelets aggregate at the site of a vascular injury, they degranulate, releasing stored substances. Serotonin, a potent vasoconstrictor, helps to constrict blood vessels and reduce blood flow to the injury site, facilitating the clotting process. This action not only aids in preventing excessive blood loss but also assists in the overall healing process.

In contrast, while white blood cells are primarily involved in immune responses and red blood cells are responsible for oxygen transport, their functions do not include the release of serotonin. Plasma cells, which are specialized B lymphocytes, produce antibodies but do not have a role in the hemostatic process or the release of serotonin. This specificity highlights why platelets are uniquely positioned as the formed element responsible for serotonin release.