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"the blood-the platelets(thrombocytes) their stories"

Downloads: 7,289 Avg Rating: 0.00 By: Mr Ovi Odiete in 2014.
platelets are colorless small non-nucleated fragments of cytoplasm,constituting cell membrane,microtubules,and cytoplasm.it contains proteins,enzymes,blood group antigens,and inorganic substances(calcium,copper,ion and magnessium.
 normal count is between 200,000 and 400,000/cumm it has three properties and normally varies physiologicall with age,sex,and high altitude. the properties are adhesiveness(the property of sticking to a rough surface caused by ADP and thromboxane A2). another property is aggregation(grouping of platelets),and agglutination(clumping together).
  it has five major functions
  1.function in blood clotting
  2.in the repair of ruptured tissues
  3.in prevention of hemostasis(blood loss)
  4.in clot retraction
  5.in defense mechanism

activators of platelets are 
1.collagen which is exposed during damage of blood vessels.
2.von willebran factor.
3.thromboxane A2
4.thrombin
5.platelet activating factor
6.ADP
7.calcium ions
8.P selectin
9.convulxin (a purified protein from snake)
 
inhibitors are
1.nitric oxide
2.clotting factors-2,9,11 and 12
3.prostacyclin
4.nucleotidases which break down ADP

   platelets develop in bone marrow and stays for usually eight to ten days,they are destroyed by tissue macrophage system in spleen.
 (splenolegamy which is enlargement of spleen,decreases platelet count,while splenectomy which is the removal of spleen increases it.)
  physiological disorders are;
 1.thrombocytopenia(decrease in platelet count)
 2.thrombocytosis(increase in platelet)
 3.thrombocythemia(persistent abnormal increase in platelet count)

Additional Authors: k.sembulingam

Document Type: Research Paper Topic Area: Health + Medicine Submitted: 29th Jun 2014
Institution: university of benin,nigeria Department: physiology Country: Nigeria
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