Blood coagulation Flashcards
describe the blood clotting process
- severed or injured blood vessel contract, restrict blood flow
- platelets aggregate form hemostatic plug
- activation of platelets initiates clotting cascade (fibrin appears)
- fibrin clot forms (secondary hemostatic plug)
what causes platelet activation?
circulating platelet binds to subendothelial collagen and vWF exposed during injury
T/F platelets do not have a structural change during activation
false
What recruits more platelet activation?
TxA2 and ADP
aspirin
inhibit platelet activation
thrombocyte
platelet
thrombocytopenia
lack of platelets
more bleeding
thrombocytosis
too many platelets
blockage of blood vessels
Draw the coagulation cascade
Coagulation PPT Slide 6
What are some coagulation factors?
phospholipids, Calcium and Gla proteins
Where are coagluation factors produced?
liver, released as zymogens
What do Gla proteins depend on?
Vitamin K
due to vitamin K dependent carboxylase
platelet count
measures # of platelets in serum
routine in CBC
what is a normal platelet count?
150,000-400,000 cells/microL
prothrombin time (PT)
rate of clotting by extrinsic and common pathways (usually amount of prothrombin in plasma)
what is normal PT?
10-14 seconds
normal INR 1.1
What medication usage should you always order a PT for?
warfarin
partial thromboplastin time (PTT)
rate of clotting time by intrinsic and common pathways
What is normal PTT?
30-42 seconds
activated clotting time
bedside test of entire clotting process
hemophilia A
factor VIII deficiency
afibrinogenemia
lack of fibrinogen
vonWillebrand Disease (vWF deficiency)
missing or defective vWF
vWF
bind to Factor VIII in serum and stabilizes it
Vitamin K deficiency
lack of vitamin K
What factors does thrombin activate?
V, VII, VIII, XI
what causes feedback amplification?
thrombin
Describe the feedback inhibition of clotting
thrombin binds thrombomodulin and activates protein C which binds protein S (and Ca).
C-S complex cleaves V, and VIII
serpin
serine protease inhibitors
regulate cascade by inhibiting coagulation or fibrinolysis
antithrombin III
irreversibly inactivates thrombin
binds heparin then thrombin, heparin dissociates
heparin
enhances antithrombin IIIs affinity for thrombin and is used as an anticoagulant
fibrinolysis
dissolving of the clot
plasminogen
plasma protein that is incorporated into clot during coagulation
what causes proteolysis of plasminogen (creates plasmin)?
tissue plasminogen activator (tPA)
urokinase (U-PA)
plasmin
protease that cleaves fibrin and clotting factors
where is tPA synthesized?
vascular endothelial cells
where is urokinase produced?
most tissues
what increase the synthesis and release of tPA and UPA?
stress
hypoxia
What two things can you treat a MI or stroke?
tPA
streptokinase
hemostatic balance
the balance of coagulation and fibrinolysis
hypercoagulation
stroke, MI, thrombosis
hypocoagulation (too much fibrinolysis)
trauma, major surgery, hemophilia
Deficiency in Factor VIII
hypocoagulation
advanced liver disease
hypocoagulation
deficiency in protein C
hypercoagulation
vitamin K deficiency
hypocoagulation
mutation in factor V at protein C cleavage site
hypercoagulation
Factor V Leiden
platelet deficiency
hypocoagulation
thrombocytopenia
Deficiency in Factor IX
hypocoagulation
hemophilia B
What are the 5 types of common coagulation disorders?
1- diffuse intravascular coagulation (DIC)
2- thrombocytopenias
3- clotting factor deficiencies
4- drug induced hypocoagulation
5- effects of surgery on coagulation (hypercoagulative effects)
What are the three drugs that cause hypocoagulation?
asprin and antiplatelet
warfarin
heparin
