Platelet

Platelets or thrombocytes are the blood cell fragments that are involved in the cellular mechanisms that lead to the formation of blood clots. Low levels or dysfunction predisposes for bleeding, while high levels - although usually asymptomatic - may increase the risk of thrombosis.

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Like red blood cells, platelets are anuclear and discoid; they measure 1.5-3.0 μm in diameter. The body has a very limited reserve of platelets and so they can be rapidly depleted. They contain RNA, a canalicular system, and several different types of granules; lysosomes (containing acid hydrolases), dense bodies (containing ADP, ATP serotonin and calcium) and alpha granules (containing fibrinogen, factor V, vitronectin, thrombospondin and von Willebrand factor), the contents of which are released upon activation of the platelet. These granule contents play an important role in both hemostasis and in the inflammatory response.

Blood: Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). Medical terms related to blood often begin in hemo- or hemato- (BE: haemo- and haemato-) from the Greek word "haima" for "blood"....

Blood clot: Redirect thrombus...

Bleeding: Bleeding is the loss of blood from the body. Children are put more in danger by bleeding as they have less blood to lose. The average adult human will be in medical danger after 2 liters (2 quarts) and could die of hypovolemic shock if more blood is lost....