12: Hemostasis 2

hyperemia

increased BF (caused by arteriole dilation)

congestion

reduced outflow of DEOXYGENATED (venous) blood

hemostasis

stoppage of bleeding

thrombosis

blood clot in intact vessel

thrombolysis

dissolution of a clot

fibrinolysis

Process of breaking down fibrin in clots.

coagulation

clotting of blood

how does hemostasis begin?

transient vasoconstriction/platelet aggregate

how does hemostatis end?

platelet plug clot at site of injury (primary hemostasis)

if the injury is too strong for a platelet plug, what happens next?

coagulation cascade, adding fibrin to the plug (secondary hemostasis)

true or false: regulatory mechanisms STOP clot from continuing to grow

TRUE

what processes dissolve the fibrin plug?

thrombolysis and fibrinolysis

normal endothelium

profibrinolytic and antithrombotic

injured endothelium

antifibrinolytic and prothrombotic

mural thrombus

blood clot attached to endothelial/lymphatic wall

thromboemoulus

blood clot free in the lumen

most important part of thrombolysis

fibrinolysis lol

what influences a thrombus to form?

virchow's triad

3 factors of virchow's traid

vascular injury, hypercoagulability, statis/turbulence

MOST IMPORTANT FACTOR of virchow's triad

vascular injury

what is involved with vascular injury (virchow's)?

endothelium and blood vessels

what is involved with hypercoagulability (virchow's)?

coagulation factors and platelets

what is involved with stasis/turbulence (virchow's)?

blood flow dynamics

what do antiplatelets do?

inhibit platelet aggregation

what inhibits non-active platelets from adhering to uninjured vessel walls?

prostacyclin (PGI2) and nitrous oxide (NO), endothelial cells expressing ADPases (breaks down ADP)

true or false: ADP is needed for platelet aggregation

TRUE

what do anticoagulents do?

inhibit blood coagulation

thrombin is factor what

2a

what does thrombomodulin do?

binds to thrombin and converts it from pro to anticoagulant

what do endothelial cells synthesize to promote fibrinolytic activity?

tissue-type plasmingoen activator (t-pa)

what does t-pa do?

clears fibrin deposits from endothelial surfaces

what happens during fibrinolysis?

cleavage of plasminogen into plasmin

what does t-pa cleave?

plasminogen to plasmin

what blocks fibrinolysis from occuring?

plasminogen activating inhibitor (PAI)

what breaks down fibrin and interferes with fibrin polymerization?

plasmin

fibrinolysis has these 3 characteristics:

pro-fibrinolytic, anti-hemostatic, anti-coagulant

3 main p;ayers in fibrinolysis

tPA, uPA, Annexin II

tPA

tissue plasminogen activator

uPA

urokinase plasminogen activator

what does uPA do?

same thing as tPA (conversts plasminogen to plasmin)

which is more potent, tPA or uPA?

tPA

what does Annexin II do?

binds phospholipids and Ca to displace coagulation factors on endothelium, inhibits formation of thrombin and factor Xa

FDPs

fibrin degradation/split products

what do FDPs act as?

weak anticoagulants

PAI-1

plasminogen activating inhibitor

what does PAI-1 do?

inhibits tPA/uPA

what does a-2 antiplasmin do?

BINDS FIRST, neutralized plasmin

what do a2-antiplasmin and a2-macroglobulin do?

inhibit activated protein C

fibrinolytic inhibitors

PAI-1, A2-antiplasmin, A2-macroglobulin

coagulation inhibitors

proteins C/S, heparan sulfate, A3, TFPI

TFPI

tissue factor pathway inhibitor

most potent coagulation inhibitor

antithrombin 3 (AT3)

what produces AT3?

endothelial cells and hepatocytes

what is the most important thing that AT3 does?

inhibits thrombin and factor Xa (part of common pathway)