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36 Cards in this Set

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  • Back
Hemostasis
stoppage of bleeding, clotting to prevent blood loss
Hemostais involves interplay between
blood vessels, thrmobocyte/platelets, and coagulation factors
Overal scheme of hemostasis
injury to a vessel
vessel constriction
thrombocyte aggregation
coagulation
what size vessels is hemostasis most effective in?
smaller
immediate response of an injured vesel is what? what does this cause?
imediate response-vessel casoconstriction
-damages endothlial leading to exposure of collage
platelets are fragments from
Megakaryocytes from the myeloid lineage
the avg. lifespan of a platelet
6-10 days
Name the secretory vessels that the platlet contains
TXA2, Serotonic, ADP, eicosinoid
What do activated platelets display?
1. platelet factor
2. membrane receptors that bind to many clotting factors, most of which are made in the liver
What is the normal concentation of platelets?
Dangerous level?
150-450 thousands cells/mm3
50 thousand
what allows platelets to adhere to collagen?
a plasma protein called von Willebrand Factor that is secreted by endothelial cells and platelets
what do platelets contain to strengthen the platelet plug?
actin and myosin
What is the role of the fibrinogen?
bridges the neighboring platelets
What can be a result of defects of platelet aggregation?
mucosal bleeds and heavy menst.
What is the most dominant hemostatic dfense agains blood loss?
clot/thrombus formation
Disorders of coagulation causes
hematomas, accumulation of blood in the tissue
hemathrosis
bleeding into a joint
How is fibrinogen formed
inactvie protein that stiumlates an enzyme
That stimulates another protein which stimulates an enzyme
That stimulates prothrombin (CF2) to convert to Thrombin (CF2A)
That stimulates Fibrinogen (CF1) to vonvert to Fibrin (CFIa)
What are the 2 types of pathways that can lead to production of thrombin
Intrinsic-everything needed in the blood
Extrinsic-some compound or factor from outside the blood necesssary
nutricional requirments of coagulation
Vitamin K-produces Prothrombin and other clotting factors
Bile salts secreted by the liver-Absorb Vit K
Calcium-needed at many steps
hemophelia
the absence of clotting factor 8or 9
about how many substances rgulate hemostasis?
50
what does aging do to anticoagulates
it decreases the number, so you are at risk for hypercoagulation
during normal activity what is the relationship btwn the # of anticoagulates to coagulates?
there are more anticoagulates
during injury what is the relationship btwn the # of anticoagulates to coagulates?
there are more procoagulates
what results in more blood loss, artery or vein damage
artery
Fxn of anticloting systems
inhibit clot formation or disolve a clot by fibrinolytic mechanisms
When are mechanisms that oppose clot formation activate
once clotting has been stimulated to limit the extent of clot formation
mechanisms that oppose clot formation
-Inhibit TXA2 w/ NO or Prostaglandin released from endothelial cells
-Tissue factor pathway inhibitor
-Thrombin
-antithrombin 3
Tissue factor pathway inhibitor
secreted from endothelial, inhibiting clotting factor x
Thrombin
can bind to thromobomodulin, an endothelial cell receptor, whic causes the thrombin to activate a plasma protein (protein C) which inactivates some of the clotting factors
antithrombin 3
plasma protein that inactivates hthrombin and several clotting factors. Activated when it binds w/ heparin, found on the endothelial cells
most common plasminogen activator
t-PA, tissue plasminogen activator, secreted by the endothelial cells
Overall scheme of the fibinolytic system
plasminogen activators activate the convesion of plasminogen to plasmin. Plasmin then digest fibrin
Anti clotting drugs
ASA-asrping to prevent profalactic
Drugs that interfere w/ Vit. K absorption
Heparin
t-PA or steptokinase-tissue plasma inactivator
Drugs that block platelet fxn
Jobs of endothelia cells
-secreted endothelin, NO, prostaclyclin, tissue factor pathway inhibitor, vWF, and t-PA
-heparin is on the surgace
-has thromomodulein receptor