hemostasis Flashcards
what factor do intrinsic & extrinsic pathways converge on?
-factor X (10)
what is the deadly triad of blood transfusions?
-acidosis
-coagulopathy
-hypothermia
“A-C-H”
the factor comes from where?
1. von wildebrands
- endothelium
what does each lab test for?
- ptt
- pt
- bleeding time
- teg
- act
- PTT tests for intrinsic and common pathways
- PT tests for extrinsic and common pathways
- bleeding time tests for platelet dysfunctions, effects of asa and vWF disease
- TEG tests for all factors in the clotting cascade
what is the time frame and pressure needed to form a clot?
less than 60 MAP for 10 seconds
heomstasis is depends on what?
time and flow
hemostasis is termed as what?
“the combined activity of vascular, platelet and plasma factors counterbalanced by regulatory mechanisms to limit accumulation of fibrin and platelets in the area of injury”
or -
the arrest of bleeding from an injured vessel
what are the 4 processes that contribute to hemostasis?
- vasoconstriction from:local (thromboxane, ADP, serotonin) and systemic (epinephrine) vasocontrictors.
- Platelets (ADP & thromboxane and von willibrand combined with GP1b) make platelets sticky
- Fibrin (calcium joins fibrin monomers into polymers)
- factor XIII- forms a net/ mesh from fibrin polymers
- what is fibrinolysis?
2. what factores cause fibrinolysis?
- the break down of the clot
- a. presence of blood clot induces secretion of TPA
b. TPA convertes plasmin”ogen” into plasmin - plasmin (also containing antithrombin III and urokinase) works on the clot
- what is the intrinsic pathway?
- what triggers this pathway and what factors are involved?
- what do these factors activate?
- intrinsic is triggered from within
- damage to vessel wall stimulates activation of factors 8, 9,11 & 12
- those factors in turn activate factor X (which causes the actual clotting cascade)
(intrinsic=inside cost -$11.98 is almost $12 (8,9,11,12))
- what is the extrinsic pathway?
- what factors trigger this pathway?
- what do these factors do?
- damage to tissue outside of the vessel ; clots blood that has escaped into tissues (extrinsic is external)
- factors III (thromboplsatin) and VII cause activation of factor X
- those factors in turn activate factor X (which causes the actual clotting cascade)
(extrinsic is an extra $37)
- what factor does both extrinsic and intrinsic pathway converge on?
- what factors does this factor join up with to form a clot (name them all)?
- all converge on factor X
2. I,II,V,X, XIII (you can get it on the first and second day of the month at the “five & dime” for thirteen bucks)
- most coagulation factors are formed where?
- what factor is made from endothelial cells?
- what factor comes from diet?
- of the factors, which are dependent on vitamin K?
- the liver
- von willebrands factor is formed by endothelial cells
- calcium (is actually not a factor but a co-factor obtained by diet)
- vitamin K dependent factors are: II, VII, IX & X
- what is the best way to measure clotting including platelets?
- what does it measure?
- what is normal?
- bleeding time
- looks at first stage of clotting:
- -aspirin inhibition of platelets
- -platelet function
- -lack of clotting factores (von willibrands disease etc). - 3-9 minutes (>12 is abnormal)
what does a platelet count do?
identifies quantitative platelet disoeders (thrombocytopeina or thrombocytosis)