Sometimes people bleed without any Inherited and acquired disorders can increase blood clotting. Clots cause legs or arms to swell. When clotting is poor, even a slight injury to a blood vessel may lead to severe blood loss. When clotting is excessive, small blood vessels in critical places can become clogged with clots.
Clogged vessels in the brain can cause strokes Overview of Stroke A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue due to loss of its blood supply cerebral infarction and symptoms that This blockage causes unstable angina or heart attack myocardial infarction , depending on the location and amount Pieces of clots from veins in the legs, pelvis, or abdomen can travel through the bloodstream to the lungs and block major arteries there pulmonary embolism Pulmonary Embolism PE Pulmonary embolism is the blocking of an artery of the lung pulmonary artery by a collection of solid material brought through the bloodstream embolus —usually a blood clot thrombus or Activity of cell-like blood particles that help in blood clotting platelets Platelets The main components of blood include Plasma Red blood cells White blood cells Platelets read more.
Activity of proteins found in blood that work with platelets to help the blood clot clotting factors. When an injury causes a blood vessel wall to break, platelets are activated. They change shape from round to spiny, stick to the broken vessel wall and each other, and begin to plug the break. They also interact with other blood proteins to form fibrin. Fibrin strands form a net that entraps more platelets and blood cells, producing a clot that plugs the break. Bleeding occurs when there is a break in a blood vessel wall.
Control of bleeding hemostasis begins when platelets in the blood become activated change shape and develop spines and stick to the injured area. The platelets form a mesh with blood cells, collagen, and other proteins. This mesh, strengthened by long strands of insoluble fibrin, entraps more platelets and blood cells, producing a clot that plugs the break.
The clot dissolves as the blood vessel heals. An injured blood vessel constricts so that blood flows out more slowly and clotting can start. At the same time, the accumulating pool of blood outside the blood vessel a hematoma presses against the vessel, helping prevent further bleeding. As soon as a blood vessel wall is damaged, a series of reactions activates platelets Platelets The main components of blood include Plasma Red blood cells White blood cells Platelets read more so that they stick to the injured area.
The "glue" that holds platelets to the blood vessel wall is von Willebrand factor, a large protein produced by the cells of the vessel wall. The proteins collagen and thrombin act at the site of the injury to induce platelets to stick together.
As platelets accumulate at the site, they form a mesh that plugs the injury. The platelets change shape from round to spiny, and they release proteins and other substances that entrap more platelets and clotting proteins in the enlarging plug that becomes a blood clot.
Formation of a clot also involves activation of a sequence of blood clotting factors, which are proteins produced mainly by the liver. There are over a dozen blood clotting factors.
They interact in a complicated series of chemical reactions that ultimately generate thrombin. Thrombin converts fibrinogen, a blood clotting factor that is normally dissolved in blood, into long strands of fibrin that radiate from the clumped platelets and form a net that entraps more platelets and blood cells. They stick together acting as a "plug. Secondary hemostasis. Platelets alone are not enough to secure the damage in the vessel wall.
A clot must form at the site of injury. The formation of a clot depends upon several substances called clotting factors. These factors activate each other in what as known as the clotting cascade. The end result of this cascade is that fibrinogen, a soluble plasma protein, is cleaved into fibrin, a nonsoluble plasma protein. The fibrin proteins stick together forming a clot. The clotting cascade occurs through two separate pathways that interact, the intrinsic and the extrinsic pathway.
Extrinsic Pathway The extrinsic pathway is activated by external trauma that causes blood to escape from the vascular system. This pathway is quicker than the intrinsic pathway. It involves factor VII. Intrinsic Pathway The intrinsic pathway is activated by trauma inside the vascular system, and is activated by platelets, exposed endothelium, chemicals, or collagen.
A cut on the skin or an internal injury creates a small tear in a blood vessel wall, which causes blood flow. Vessel constriction. To control blood loss, the blood vessel immediately narrows called constriction , which limits blood flow through the vessel. Platelet plug.
In response to the injury, tiny cells in the blood called platelets are activated. The platelets stick to one another and to the wound site to form a plug. The protein von Willebrand factor VWF helps the platelets stick to each other and to the blood vessel wall.
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