Blood Coagulation and wound repair Flashcards
What is hemostasis?
set of processes that will help you from bleeding out
steps of blood clotting
injury –> spasm –> formation of platelet plug –> fibrin clot
What is primary hemostasis?
vasoconstriction and platelet response
What does serotonin play a role in?
vasoconstriction near site of injury
What is secondary hemostasis?
clotting cascade
What does cleavage of fibrinogen by thrombin do?
make insoluble fibrin that forms cross-linked fibrin mesh at the site of injury
What do platelets release when binding?
ADP, serotonin, and thromboxane A2
What does thromboxane A2 do?
cause vasoconstriction and attach other platelets
What is a platelet plug?
aggregation of many platelets stimulated by thromboxane A2 and ADP
What is serotonin derived from?
tryptophan (in turkey)
What is a precursor for thromboxane A2?
arachidonic acid
What is the process of platelet activation?
GPIIb/IIIa undergoes conformational change to reveal vWF or fibrinogen
-binds to vWF and promotes strong adhesion
Are platelets active all the time?
no do not become activated until there is an injury
What allows platelets to bind in correct spot?
von Willebrand factor
What allows platelets to bind to one another?
fibrinogen
Is platelet aggregation fast?
yes happens in minutes not hours
What activates the external clotting cascade?
external trauma that allows blood to escape from the vascular system
(factor 7)
Is the extrinsic pathway quicker or slower than intrinsic?
quicker
What activates the intrinsic pathway?
trauma inside the vascular system and platelets
(factor 12, 11, 9, and 8)
What are the common factors in the extrinsic and intrinsic pathway?
1, 2, 5, and 10
Steps of the common pathway
-prothrombin to thrombin
-fibrinogen to fibrin
What is factor I?
fibrinogen
-cleaved by thrombin to form fibrin clot
What is factor II?
prothrombin
-activated on surface of activated platelets by prothrombinase complex
What activates factor XIII?
activated by thrombin in presence of Ca2+
-stabilizs fibrin clot by covalent cross linking
cross-linking is dependent on what?
calcium
What is von Willebrand factor?
associated with subendothelial connective tissue
-serves as a bridge between platelet, glycoprotein GPIb/IX, and collagen
What is thrombomodulin?
protein on the surface of endothelial cells
-binds thrombin and activates protein C
-modulates clotting pathway (idk which one)
What is the role of carboxyglutamate?
hold enzymes onto the surface of the cell membrane
Which molecules have carboxyglutamate residues?
thrombin and factors 7, 9, and 10
What is vitamin K?
cofactor for carboxyglutamates
-fat soluble
What are the 4 fat soluble vitamins?
D, E, A, and K
What happens if you do not have enough Vitamin K?
it is needed to turn glutamate to carboxyglutamate which is very necessary in common pathway so without it you have clotting issues
What do fibrin molecules look like?
lincoln logs
-they aggregate together and make stable arrangement
What catalyzes crosslinking of fibrin?
transglutaminase (factor 13)
What activates the cleavage of fibrin?
thrombin and thrombin-activatable fibrinolysis inhibitor
What are the four steps of wound healing?
hemostasis
inflammation
proliferation
remodeling
What is inflammation stage?
bacteria and debris are phagocytosed and removed from wound site
-factors cause migration and division of cells in proliferation stage
-take a few days
what is the proliferative stage?
angiogenesis, collagen deposition, granulation tissue formation, epithelialization, and wound contraction
What is the remodeling phase?
collagen is remodel and realigned along tension force lines and cells no linger needed are removed by apoptosis
what causes scaring?
overproduction of the matrix
what is fibronectin?
works as a regulator of platelet function and mediator of hemostasis
characteristics of the plasma form of fibronectin:
secreted by hepatocytes and modulates platelet formation
characteristics of cellular form of fibronectin:
secreted by cells as part of extracellular matrix and functions as a scaffold protein
What is acid citrate dextrose?
solution used to disrupt platelet coagulation and prevent clotting
How acid citrate dextrose solution prevent blood clotting?
Citrate binds to the calcium present and does not allow it to bind and start the clotting cascade
What is prothrombin time?
test to diagnose a bleeding disorder
-measured in seconds
-measure of the integrity of the extrinsic pathway and final common pathway
What is a healthy international normalized ratio?
1.1 or below
What does an INR range of 2-3 mean?
effective therapeutic range for people that are taking warfarin for blood clots or atrial fibrilation
-inhibiting clotting
What can interfere with wound healing?
diabetes, venous or arterial disease, old age, or infection
Drugs that reduce blood clots:
warfarin, pradaxa, xarelto, eliquis, plavix
What does warfarin do?
depletes vitamin K reserves to prevent clotting and competitively inhibits VKORC1(essential enzyme for activating vitamin K)
what do we use coumadin for?
to kill the nasty little rats
