MTAP W4 (Hematology: Checkpoint notes: Hemostasis) Flashcards
- process of forming barrier to blood loss and maintain blood in fluid state
when out of balance:
1. hemorrhage
2. thrombosis
hemostasis
formation of primary hemostatic plug or platelet plug
primary hemostasis
components:
1. vascular system
2. platelets
primary hemostasis
events include: vasoconstriction, platelet adhesion, platelet aggregation=initial plug
primary hemostasis
formation of stable fibrin clot
secondary hemostasis
components: coagulation factors
secondary hemostasis
events include: fibrin stabilization by factor XIII, coag factors interact on platelet surface to produce FIBRIN
secondary hemostasis
secondary hemostasis
fibrin stabilization by factor -
factor XIII/13
physiologic process that removes insoluble fibrin deposits by enzymatic digestion of stabilized fibrin polymers
fibrinolysis
gradual digestion and removal of fibrin clot as healing occurs
fibrinolysis
release of tissue plasminogen activator, conversion of plasminogen to plasmin, conversion of fibrin to fibrin degradation products
fibrinolysis
Primary hemostasis: Component
consist of ENDOTHELIAL CELLS, basement membrane and subendothelial connective tissue
tunica intima
Primary hemostasis: Component
thicker in arteries than in veins, contains smooth muscle cells which contract and expand
tunica media
Primary hemostasis: Component
thicker in veins than in arteries
tunica adventitia/externa
Primary hemostasis: Component
lines the blood vessels
endothelium
Primary hemostasis: Anticoagulant Properties
eicosonaid platelet inhibitor and vasodilator
prostacyclin
Primary hemostasis: Anticoagulant Properties
vascular ‘relaxing’ factor
nitric oxide
Primary hemostasis: Anticoagulant Properties
glycosaminoglycan that enhances antithrombin activity
heparan sulfate
Primary hemostasis: Anticoagulant Properties
extrinsic pathway regulator
tissue factor pathway inhibitor
Primary hemostasis: Anticoagulant Properties
endothelial surface receptor for thrombin
thrombomodulin
Primary hemostasis: Anticoagulant Properties
activating fibrinolysis
tissue plasminogen activator
protein C pathway is catalyzed by
thrombomodulin
downregulates coagulation by digesting activated factors V and VIII, thereby inhibiting thrombin formation
protein C pathway
Primary hemostasis: Procoagulant Properties
smooth muscle cells in arterioles and arteries induce -
vasoconstriction
Primary hemostasis: Procoagulant Properties
exposed subendothelial - bind VWF and platelets
collagen
Primary hemostasis: Procoagulant Properties
damaged/activated ECs secrete - and adhesion molecules
vWF
Primary hemostasis: Fibrinolytic Properties
activates fibrinolysis
tissue plasminogen activator
production is influenced by THROMBOPOIETIN prdocued in the liver or kidney
secretes coagulation factors stored in their granules
platelets
first response to injured vessel
vasoconstriction
vasoconstriction is initiated by - and - derived from platelets and endothelial cells
Serotonin
Thromboxane A
attachment of platelets to collagen and other components
adhesion
adhesion: collagen
in vivo
adhesion: glass
in vitro
Primary hemostasis
at HIGH SHEAR rates, platelet adhesion requires presence of both - and receptor -
vWF and GPIB/IX/V
Primary hemostasis
at LOW SHEAR rates - receptors mediate direct collagen binding
GPIaIIa and GPVI
Primary hemostasis
occurs within 1-2mins after a break
PASSIVE< non-energy-requiring process and potentially reversinle
vasoconstriction
multimeric protein that contains binding sites for both GP1b and IX
vWF
synthesized by ENDOTHELIAL CELLS and MEGAKARYOCYTES
vWF
vWF; stored in intracellular granules and secreted into the plasma
- in endothelial cells
weibel palade bodies
vWF; stored in intracellular granules and secreted into the plasma
- in platelets
alpha granules
stimulate platelets and activate them
platelet agonists
- agonists
1.ADP
2.PAF/platelet-activating factor
3.serotonin
4. thromboxane A
‘STAP’
platelet-derived agonist
- agonists
1.collagen
2. thrombin
3. epinephrine
‘CET’
non-platelet-derived agonist
strong agonist does not require - activity
cyclooxygenase
the most potent activator of platelets in vivo
thrombin
during platelet activation, PHOPHOLIPASE A2 converts phospholipid to -
arachidonic acid
ARACHIDONIC acid is converted to prostaglandin endoperoxidase by -
cyclooxygenase
causes release of ca which promotes platelet aggregation and vasoconstriction
TXA2
potent agonist and can stimulate platelet activation and secretion
TXA2
permanently blocks the action of cyclooxygenase-1 and TXA2 synthesis, impairing plt function
aspirin/acetylsalisylic acid
Platelet DENSE BODIES-small molecules
component: -
agonist for platelets
ADP
Platelet DENSE BODIES-small molecules
component: -
agonist for cells other than platelets; activates ca influx channel in outer membrane
ATP
Platelet DENSE BODIES-small molecules
component: -
platelet activation
calcium
Platelet DENSE BODIES-small molecules
component: -
vasoconstriction, platelet antagonist
serotonin
strong agonist does not require - activity
cyclooxygenase
- stimulation results in increased cytoplasmic calcium, more plt release and the appearance of active fibrinogen receptors
ADP
PLATELET ALPHA GRANULES- LARGE GRANULES
GROUP 1-HEMOSTATIC PROTEINS
platelet aggregation; conversion to fibrin
fibrinogen
PLATELET ALPHA GRANULES- LARGE GRANULES
GROUP 1-HEMOSTATIC PROTEINS
fibrin formation
Factor V, XI
PLATELET ALPHA GRANULES- LARGE GRANULES
GROUP 1-HEMOSTATIC PROTEINS
plt adhesion; carries FVIII in plasma
VWF
PLATELET ALPHA GRANULES- LARGE GRANULES
GROUP 1-HEMOSTATIC PROTEINS
fibrinolysis
plasminogen
PLATELET ALPHA GRANULES- LARGE GRANULES
GROUP 1-HEMOSTATIC PROTEINS
when released from activated plt, protect newly formed clots from lysis
PAI-a, a2-antiplasmin
PLATELET ALPHA GRANULES- LARGE GRANULES
GROUP 2-NONHEMOSTATIC PROTEINS
PLATELET SPECIFIC
chemoattractant for neutrophils, fibroblast
neutralizes heparin
b-thromboglobulin
PLATELET ALPHA GRANULES- LARGE GRANULES
GROUP 2-NONHEMOSTATIC PROTEINS
PLATELET SPECIFIC
weak chemoattractant for neutrophils, fibroblasts
neutralizes heparin
platelet factor 4