Module 3_Mechanisms of Normal Hemostasis Flashcards
(28 cards)
hemostasis
prevention and arrest of bleeding
vascular component
blood vessels and surround ing sub-endothelium
what are the 5 major components in hemostasis?
vascular, platelet, plasma components (coagulation system, fibrinolytic system, natural anticoagulants & inhibitors
what are firstly exposed during injury?
platelets and plasma components to the sub endothelial tissues (collagen and III - tissue thromboplastin)
what is the sequence of hemostatic plug formation following the injury?
- release of activator
- blood exposed to sub endothelium
- vasoconstriction
- platelet adhesion to subendo
- platelet aggreg - temp plug
- extrinsic coagulation -fibrin formation - 2ndry platelet aggress which is permanent
- intrinsic coagulation - fibrin formation
- platelet retraction - hemostatic plug
- fibrinolysis and action of natural anticoagulants
what is vascular potency?
keep blood cells from leaking out of circulation while allowing diapedesis of mobile cells
what are the 2 functions of vasoconstriction in injury?
- reduce blood flow
2. promoting platelet adhesion
what are the two types of vasoconstriction?
- muscular: immediate
- humoral: delayed. release of vasoconstrictor substances that activate platelets and nearby intact endothelial cells to release endothelin. Endothelin induces SM contraction
what is tissue thromboplastin and its function?
III, lipoprotein released from injury cell.
activates VII in extrinsic pathway.
what is plasminogen activator (tPA) and its function?
activates the fibrinolytic system.
some released by injury, more release after healing. dissolve the clot.
what happen when collagen in contact with plasma?
- adhesion of blood platelets to subendothelium
2. activation XII of intrinsic pathway
In thrombopoiesis, what are the two unique factors of megakaryocytes differ from RBC production?
- get larger as they mature
2. no cellular division. but has endomitosis (repeated nuclear divisions
what and where is platelet made from?
cytoplasmic fragment of the megakaryocyte. In bone marrow and lifespan 8~10 days in circulation
T or F: 20% of the platelet may be larger than normal (megathrombocytes)
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what are the three zones of platelet?
peripheral zone, sol-gel zone, organelle zone
what is peripheral zone and its function?
in the plasma membrane, has peripheral proteins - glycocalys
function: adhesion and aggregation of platelets
what is sol-gel zone and its function?
just below PM, has microtubules and microfilaments, contractile proteins (thrombosthenin and actomyosin).
function: platelet retraction and shape changes (viscous metamorphosis during secondary aggregation)
what is organelle zone?
It is the cytoplasm and its components: granules, mitochondria, dense tubular system, canicular system.
what is canicular system and its function?
an extensive canal system from in and out
Function: It carries granular contents to surface
what is dense body?
2~10 in each platelet, rich in serotonin, vasoactive catecholamines (nor-epi and DOP), nucleotides (AMP, ADP, ATP), Ca2+, pyrophosphate
what is alpha (translucent) granule?
20~200/platelet.
contains: III, Fibrinogen, thrombospondin (promotes plate aggreg), PF-IV
…… and unimportantly, B-thromboglogulin (antiheparin), platelet drived growth factor (PDGF that induces new tissues growth), coag factors XIII, V, VWF, albumin, alpha2-antiplasmin (inhibits fibrinolysis).
T/F: 70% platelets are circulating, 30% sequestered
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T/F: in the 30% sequestered platelet distribution, 17% in splenic sinusoid and 13% in microcirculation and sinusoids of the liver, lungs and bone marrow.
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What is platelet factor and its function?
substance that is absorbed onto platelet membrane or carried in the platelet granule. It is released during release rxn and influence hemostasis
