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glossary:hematopoiesis

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glossary:hematopoiesis [2007/09/18 10:09]
Pat O'Connor
glossary:hematopoiesis [2012/10/16 14:40] (current)
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 +The production of all types of blood cells generated by a remarkable self-regulated system that is responsive to the demands put upon it. 
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 +The levels of the different types of the [[white blood cells]] in the [[granulocyte]] series (the [[neutrophil]]s,​ [[eosinophil]]s,​ and [[basophil]]s) are normally maintained within preset normal ranges and prompt adjustments are made in response to demands such as [[infection]]s,​ allergic reactions, etc. 
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 +In much the same way, the levels of the other types of white cells (the [[monocytes]] and [[lymphocytes]]),​ the platelet, and red blood cell are regulated within normal ranges and respond rapidly to demands. The [[monocytes]] respond to [[infection]]s,​ the [[lymphocytes]] respond to immune challenges, the platelets respond to hemorrhage or [[inflammation]],​ and the [[red blood cells]] ([[erythrocytes]]) respond to [[hypoxia]] (low oxygen levels). ​
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 +When hematopoiesis is disturbed, the first [[cell]]s to drop are usually the [[neutrophil]]s (which have a life span in the [[blood]] of only 6 to 8 hours) followed by [[platelets]] (with a 10-day life span). [[Anemia]] develops more slowly, over a much longer span of time (since the [[red blood cells]] have a 120-day lifespan). ​
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 +All types of [[blood]] cells are derived from primitive cells (stem cells) in the [[bone marrow]]. The production of blood cells is largely controlled by feedback. When the demand for production of cells of a particular type of cells increases or the levels of the cells fall in [[blood]], stimulatory substances called [[cytokines]] are released. And the cytokines stimulate the [[stem cell]]s to generate new mature blood cells. This occurs in the few days required for blood cell maturation. ​
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 +The production of [[lymphocytes]] is an exception to this neat scenario. Many more [[lymphocytes]] are generated daily than are needed in the [[blood]]. Most lymphocytes are destroyed during development. Thus, [[lymphopoiesis]] (the production of lymphocytes) is inefficient compared to all other hematopoiesis.
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 +Common Misspellings:​ hemopoiesis ​
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glossary/hematopoiesis.txt ยท Last modified: 2012/10/16 14:40 (external edit)