Platelets or thrombocytes are the blood cells that are involved in the cellular mechanisms of primary haemostasis 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.

Anatomy

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Like red blood cells, platelets are anuclear (no cell nucleus) and discoid (disc shaped); they measure 1.5–3.0 μm in diameter. The body has a very limited reserve of platelets, 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.

Physiology

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Production

Platelets are produced in the bone marrow; the progenitor cell for platelets is the megakaryocyte. This large, multinucleated cell sheds platelets into the circulation. Thrombopoietin (c-mpl ligand) is a hormone, mainly produced by the liver, that stimulates platelet production. It is bound to circulating platelets; if platelet levels are adequate, serum levels remain low. If the platelet count is decreased, more thrombopoeitin circulates freely and increases marrow production.

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Platelets - Twitter Search

gave platelets 2nd time. Means more now: friend clinging to life with acute leukemia. - Easy to donate. Helps save lives.
fnblanchard (Frank Blanchard) Wed, 04 Nov 2009 19:29:55 -0000
gave platelets 2nd time. Means more now: friend clinging to life with acute leukemia. - Easy to donate. Helps save lives.
I'm donating platelets tom. at 1pm anyone want to come w/me and donate. They are in desperate need in SC. Come help or keep me company.
goodtwin326 (Amy Counts) Wed, 04 Nov 2009 17:50:09 -0000
I'm donating platelets tom. at 1pm anyone want to come w/me and donate. They are in desperate need in SC. Come help or keep me company.
Offloading platelets again today. in Roseville, CA
marygriff (Mary Griffith) Wed, 04 Nov 2009 16:47:23 -0000
Offloading platelets again today. in Roseville, CA
The coarse, pitchy laugh of an insincere girl elicits a generous helping of aneurysm~causing platelets to hit my bloodstream. I know it.
S1DC (Joseph Schell) Wed, 04 Nov 2009 15:33:28 -0000
The coarse, pitchy laugh of an insincere girl elicits a generous helping of aneurysm~causing platelets to hit my bloodstream. I know it.
Science News Existence of a microRNA pathway in anucleate platelets http://bit.ly/2UNIvj
sciencestage (ScienceStage) Wed, 04 Nov 2009 13:03:14 -0000
Science News Existence of a microRNA pathway in anucleate platelets http://bit.ly/2UNIvj
from 230,000+ platelets it dropped to 190,000. T.T
anaisbethel (Annis Bethel Realiza) Wed, 04 Nov 2009 12:47:26 -0000
from 230,000+ platelets it dropped to 190,000. T.T

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