Hemostaas

Hemostaas is not a standard term in current medical literature and is most likely a misspelling or variant of haemostasis or homeostasis. In standard medical usage, haemostasis describes the process that stops bleeding and maintains vessel integrity after injury.

Haemostasis comprises three overlapping phases: vascular spasm, platelet plug formation, and coagulation. Vascular constriction reduces blood flow to the damaged area. Platelets adhere to exposed subendothelial collagen, become activated, release granules, and recruit additional platelets to form a temporary plug, aided by von Willebrand factor. The coagulation cascade stabilizes the plug through a series of proteolytic activations that convert fibrinogen to fibrin, creating a durable clot. This cascade involves intrinsic and extrinsic pathways converging on thrombin generation. Endothelial cells also regulate coagulation by producing antithrombotic and procoagulant signals.

Clot stabilization and resolution involve clot retraction and fibrinolysis, when plasmin degrades fibrin. The balance between procoagulant and anticoagulant forces influences clot formation and dissolution. Dysregulation can lead to bleeding disorders, such as hemophilia A or B and von Willebrand disease, or thrombotic conditions.

Understanding haemostasis is central to medicine, including surgery, trauma care, and the management of liver disease and pregnancy. Diagnostic tests include prothrombin time and activated partial thromboplastin time, while treatments include antifibrinolytics, factor concentrates, and anticoagulants.