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35 Cards in this Set
- Front
- Back
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First thing platelets do? |
form a primary haemostatic plug. |
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platelets provide what type of surface? |
phosphlipid. |
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Which clotting factors do platelets provide a resevoir of? |
v, ix etc and calcium |
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How do platelets promote healing of the vasuclar endothelium? |
platelet derived growth factor!! |
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Normallifespan |
7-10days |
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normal range? |
150-400x109/l. |
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Thrombocytopaenia |
isa clinical state where there are low numbers of circulating platelets |
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what can cause Thrombocytopaenia |
Leukemia, aplastic anaemia Cytotoxic drugs during BM transplant massive blood transfusions. |
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what is the lineage of platelets. |
CFU-GEMM, CFU-MK6, MEGAKARYOBLAST, PREMEGAKARYOCYTE, MEGAKARYOCYTE –several thousandper megakaryocyte |
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where are platelets found |
1/3 in circulation 2/3 in spleen |
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What is the production of platelets modulated by? |
Thrombopoeitin which is produced by the liver and kidney |
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c-MPL receptors are on platelets and megakaryocytes, how does it regulate production of platelets? |
TPO is removed from circulation by c-MPL, If there are more megakaryocytes and platelts in the blood less will get to the bm. Most TPO is produced by the liver, small amounts from kidneys |
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what are the alpha-granules in platelets structure? |
clotting factor granule. fibrinogen, fibronectin, thrombospondin, b-thromboglobulin, PDGF, vWF, Factors V, IX, XIII |
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Electron dense granule? |
ATP / ADP / Ca2+ / serotonin |
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canicular system purpose? |
enable contents of granules to escape readily |
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sub membranour filament? |
allows contraction when neccesarry |
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resting state energy source? |
mito |
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activated state energy source? |
glycolysis |
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ATP in electron dense granules also used for? |
ADP source which signals other platelets |
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fibrinogen, fibronectin, thrombospondin, b-thromboglobulin, PDGF, vWF, Factors V, IX, XIII |
throbospondin fibronectin - adhesion throboglobulin recruits fibroblasts. pdgf - |
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surface glycoproteins - |
receptors for VWF, FIBRINOGEN, COLLAGEN, |
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vwf - has receptors for collagen and platlet glycoproteins. |
allows platelets to bind to surface, and also upregulates adhesion molecule production for adherance to vascular endothelium |
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arachadoni acid - |
oxygenated then produces prostagladins - |
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prostaglandins produce? |
acted on by thromboxane synthase - which produces throboxan a2 |
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which is the "point of no return" for the platelt activation |
thromboxane a2 production by thromboxane synthase. |
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How does this provide a safety mechanism? |
prevents clots and throwmobotic disorder at intacts area. |
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neurtal charged and negatively charged phospholipids reside where on the platelts? |
neutral charge on the outside, negatively charged on the inside. |
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when activated phospholipid scrambalase does what? |
negative charged phospholips go outside, produces negative surface for producing the plug! |
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serotonin is importatn because it is a what? |
vaso constrictor. |
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VWF |
allows the platelets to bind to eachother. |
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after first collagen is covered another activating system is required. what is it? |
ADP picked up via GPCR and activates. GDP replaced by GTP, dissociated B and Y part, exposing A molecule active site - interacts further activation of platelets. |
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platelets activated either by cell surface phospholipid receptors or what to other methods? |
GPCR (ADP) |
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ASPIRIN INHIBITS CYCLOOXYGENASE, this is temporary in vascular endothelium but permenant in platelets why? |
no nucleus in platelets |
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coagulation is combination of |
serine proteases. |
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christmas disease otherwise known as |
haemophilia b |
