Definition and Process of Hemostasis - Hemostasis is the process to prevent and stop bleeding in biology. - It is the first stage of wound healing. - Hemostasis involves coagulation, which changes blood from a liquid to a gel. - Intact blood vessels prevent blood clotting with certain molecules and inhibit platelet aggregation. - When blood vessel endothelium is damaged, von Willebrand factor is secreted to initiate hemostasis.

Steps of Hemostasis Mechanism - Vascular spasm is the first response of blood vessels to injury, reducing blood flow and promoting vasoconstriction. - Platelet plug formation occurs when platelets adhere to damaged endothelium and release granules. - Coagulation or blood clotting reinforces the platelet plug with fibrin threads. - Platelets play a major role in primary hemostasis by creating the platelet plug. - Hemostasis is maintained through vascular spasm, platelet plug formation, and clot formation.

Platelets in Hemostasis - Platelets adhere to the sub-endothelium surface of a damaged blood vessel. - Platelets release cytoplasmic granules containing serotonin, ADP, and thromboxane A2. - ADP attracts more platelets to the affected area. - Serotonin acts as a vasoconstrictor. - Thromboxane A2 assists in platelet aggregation, vasoconstriction, and degranulation.

Clot Formation in Hemostasis - Once the platelet plug is formed, coagulation cascade is activated. - Coagulation cascade leads to the formation of fibrin from inactive fibrinogen plasma protein. - Fibrin mesh is produced around the platelet plug, creating a secondary hemostasis plug. - Red and white blood cells can be trapped in the clot, making it harder. - Blood clot formation is essential for wound healing but can cause health problems if detached.

Types of Hemostasis - Hemostasis can be achieved through natural means or with assistance during surgery or medical treatment. - Chemical, mechanical, or physical agents can be used for hemostasis. - The type of hemostasis used depends on the situation. - Developmental hemostasis refers to differences in the haemostatic system between children and adults. - In emergency medicine, hemostatic agents are primary tools for smaller bleeding injuries.