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| '''Platelets''', or '''thrombocytes''', are ] |
'''Platelets''', or '''thrombocytes''', are the ]]that are involved in the cellular mechanisms that lead to the formation of ] ]s. Like ] they are anuclear.They do however contain ] and several different types of granules the contents of which are released upon activation of the platelet. These granule contents play an important role in both ] and in the bodies imflammatoty response. | ||
| They are activated when brought into contact with ] exposed when the ] blood vessel lining is damaged or with receptors expressed on ]or the endothelial cells of the blood vessels. Once activated they release a number of different] and platelet activating and bind together and to the forming ] clot. | |||
| Platelets are not cells in the conventional sense, but are fragmented pieces of the ] of ]s in the ], released from the ] into the bloodstream. | |||
| Platelets are separated from ] using a ]. This is necessary because platelets do not survive the cold temperatures used to keep ]s, so they must be stored separately. People with few platelets or platelets that do not work well benefit from such donations. ] is pale ]. | Platelets are separated from ] using a ]. This is necessary because platelets do not survive the cold temperatures used to keep ]s, so they must be stored separately. People with few platelets or platelets that do not work well benefit from such donations. ] is pale ]. | ||
Revision as of 10:19, 3 November 2004
Platelets, or thrombocytes, are the bloodcellthat are involved in the cellular mechanisms that lead to the formation of blood clots. Like red blood cells they are anuclear.They do however contain RNA and several different types of granules the contents of which are released upon activation of the platelet. These granule contents play an important role in both hemostasis and in the bodies imflammatoty response.
They are activated when brought into contact with collagen exposed when the endothelial blood vessel lining is damaged or with receptors expressed on white blood cellsor the endothelial cells of the blood vessels. Once activated they release a number of differentcoagulation factors and platelet activating and bind together and to the forming fibrin clot.
Platelets are separated from donated blood using a centrifuge. This is necessary because platelets do not survive the cold temperatures used to keep red blood cells, so they must be stored separately. People with few platelets or platelets that do not work well benefit from such donations. Platelet concentrate is pale orange.
A normal platelet count in a healthy person is between 150 and 400 (x 10/L of blood). People can live independently with a count as low as 20. People can live in hospital with a count as low as 5, but spontaneous bleeding gets to be a problem. Platelets can be transfused if a patient's platelet count falls too low. A low platelet count is called thrombocytopenia, having too many platelets is called thrombocytosis.
Thrombocytopenia may be caused by the drugs that stimulate the production of antibodies against platelets. This condition is called "Drug-induced immune thrombocytopenia"
platelet diseases
- disorders of platelet number
- disorders of platelet adhesion
- disorders of platelet aggregation
- disorders of platelet release
- decreased cyclooxygenase activity, induced or congenital
- granule storage pool defects, acquired or congenital
- disorders of platelet coagulant activity
- related disorders
See also:
| Myeloid blood cells and plasma | |||||||||||||||||
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| Hematopoiesis |
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| Myeloid tissue |
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| Other | |||||||||||||||||