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In biology, hemostasis or haemostasis is a process to prevent and stop bleeding, meaning to keep blood within a damaged blood vessel (the opposite of hemostasis is hemorrhage). It is the first stage of wound healing. Hemostasis involves three major steps: vasoconstriction; temporary blockage of a hole in a damaged blood vessel by a platelet plug
The maturation phase can last for a year or longer, similarly depending on wound type. [28] As the phase progresses, the tensile strength of the wound increases. [28] Collagen will reach approximately 20% of its tensile strength after three weeks, increasing to 80% after 12 months. The maximum scar strength is 80% of that of unwounded skin. [57]
The coagulation process occurs in two phases. First is the initiation phase, which occurs in tissue-factor-expressing cells. This is followed by the propagation phase, which occurs on activated platelets. The initiation phase, mediated by the tissue factor exposure, proceeds via the classic extrinsic pathway and contributes to about 5% of ...
The platelet plug, also known as the hemostatic plug or platelet thrombus, is an aggregation of platelets formed during early stages of hemostasis in response to one or more injuries to blood vessel walls. After platelets are recruited and begin to accumulate around the breakage, their “sticky” nature allows them to adhere to each other.
Hemostasis involves several components. The main components of the hemostatic system include platelets and the coagulation system. Platelets are small blood components that form a plug in the blood vessel wall that stops bleeding. Platelets also produce a variety of substances that stimulate the production of a blood clot.
As hemostasis is a basic function of thrombocytes in mammals, it also has its uses in possible infection confinement. [7] In case of injury, platelets, together with the coagulation cascade, provide the first line of defense by forming a blood clot. Hemostasis and host defense were thus intertwined in evolution.
This method of hemostasis was largely forgotten until it was rediscovered by a French barber-surgeon, Ambroise Paré, in the 16th century. He made the predecessor to the modern hemostat and called it the Bec de Corbin (crow's beak). With it he could clamp a bleeding vessel before securing it with a ligature.
Platelets are regulators of hemostasis and thrombosis. Platelets become active in the blood following vascular injury. Vascular injury causes platelets to stick to the cellular matrix that is exposed under the endothelium, form a platelet plug, and then form a thrombus .