Introduction to Hemostasis Flashcards
complex physiological process that keeps circulating blood in fluit state and produces clot in injury
hemostasis
discharge of blood from blood vessels to the extravascular space by any means
hemorrhage
small pinpoint purplish red hemorrhagic spots caused by inability of capillary to withstand pressure and trauma
petechiae
the size of petechiae are approximately
3 mm
3 mechanisms in petechiea formation in dengue
- predilection to endothelial destruction
- low megakaryocyte production
- platelets coated by viral products and eliminated by RES
blood in LARGE but shallow area of the skin or mucous membrane due to lack of supporting tissues
Ecchymoses
color change of ecchymosis
black
blue
greenish brown
yellow
change in color of ecchymoses is due to
hemoglobin oxidation and subsequent transport to liver by albumin
blood in SMALL areas of the skin but goes deep into the tissues due to absorption of trauma by supporting tissues
pupura
swelling or tumor in the tissues that contains clotted blood
hematoma
nose bleeding due to sensitive mucous membranes
epistaxis
blood in the sputum expectorated due to hemorrhage in the lungs, trachea, larynx or bronchi
hemoptysis
vomiting blood
hematemesis
usually in hemophilia patients where blood escapes to joint cavity
hemarthrosis
hormonal imblance causing excessive menstrual bleeding
menorrhagia
basic components of hemostasis
extravascular
vascular
intravascular
the tissues surrounding the blood vessel that swell to provide back pressure to trap escaped blood
extravascular component
the ability of the extravascular component to aid in hemostais depends on these three factors
bulk of the surrounding tissue
type of the surrounding tissue
tone of the surrounding tissue
a wound in the fleshy part of the thigh would not bleed as profusely as one in the scalp
bulk of surrounding tissue
skeletal muscle is wmore absorbent and effective in arresting hemorrhage than loose connective tissue
type of surrounding tissue
identical wounds in a 17 year old with greater tissue elasticity that a 71 years old
tone of surrounding tissue
involves the vessels through which blood flows
vascular component
the role.played by vessels depends on these
size of vessel
amount of smooth muscle tossue
integrity of endothelial cell lining
involves the coagulation and fibrinolytic factors (promoters and inhibitors)
intravascular component
the term easy bruisability refers to
individuals with extensive or repeated purpura and ecchymoses
color change of purpura
red purple (hgb deposition)
greenish yellow (biliverdin)
intact red cells in urine
hematuria
hemoglobin in the urine
hemoglobinuria
stool containing dark red or black blood
melena
conditions associated with excessive bleeding
hypocoagulable state
conditions or uncontrolled hemostasis
hypercoagulable states
basic sequence of events in primary and secondary hemostasis after vessel injury
- vasoconstriction
- platelet adhesion
- platelet aggregation
- fibrin- platelet plug formation
- fibrin stabilization
controlled by vessel smooth muscle, enhanced by chemicals secreted by platelets
vasoconstriction
adhesion to exposed subendothelial connective tissue
platelet adhesion
adhesion amd interaction of platelets to one another to form initial plug
platelet aggregation
coagulation factors interact with each other on the surface of the platelte to produce fibrin
fibrin platelet plug formation
mediated by factor XIII
fibrin stabilization
parts of a capillary
endothelial cell layer
basement membrane
pericytes
junctions or slits
tunica intima or interna components
endothelium
subendothelium composed of
- basement membrane
- elastic connective tissue
- collagen
tunica media components
smooth muscle cells
connective tissue
collagen fibers
fibroblast
tunica externa or adventitia layers
connective tissue fibroblast
collagen fibers
intimate contact with blood
tunica intima
mediates vasoconstriction and vasodilation
tunica media
thicker wall
arteries
thinner wall
vein
larger lumen
vein
smaller lumen
arteries
increased pressure
arteries
have valves in their tunica intima
veins
Significant in keeping the blood in liquid state
intact endothelium
anti thrmobotic mechanisms of the intact blood
- devoid of thrombogenic substances
- coagulation proteins are inactive
- brisk flow of blood
- synthesis of 13 HODE
2 substances that stimulate clot formation
collagen
tissue factor
collagen is involved in ____ by activation of factor ___
intrinsic pathway; XII
tissue factor is involved in ___ by activation of factor __
extrinsic pathway; VII
normally found beneath the submembrane
collagen
synthesized by all cells except the endothelial cells
tissue factor
even if endothelial linong sloughs off, clotitng does not progress due to this
brisk flow of blood
natural barrier that prevents platelet attachment to the endothelium
13-hydroxyoctadecadienoic acid
events of primary hemostasis
- injured endothelium
- platelet involvement
- platelet plug production
events of secondary hemostasis
- coagulation factors
- stable platelet-fibrin clot
- fibrinolysis
4 physiological response to vessel injury
vasoconstriction
platelet activation
coagulation
fibrinolysis
2 biochemicals promoting vasoconstriction
- serotonin (from dense granules)
- thrmboxane A2 precursor
facilitates platelet adhesion
gp Ib/IX and vWF
facilitates platelet aggregation
gp IIb /IIIa and ADP
substances released from or found on the surface of intact endothelial cells
prostacyclin (PGI2)
adenosine
thrombomodulin
heparan sulfate
tissue plasminogen activator
von Willebrand factor
hemostatic role: prostacyclin (PGI2)
anticoagulant
reduces blood flow rate
hemostatic role: adenosine
reduces blood flow rate
hemostatic role: thrombomodulin
anticoagulant
fibrinolytic
hemostatic role: heparan sulfate
anticoagulant
hemostatic role: tissue plasminogen activator
fibrinolytic
hemostatic role: ADPase
anticoagulant
hemostatic role: plasminogen activator inhibitor-1
antifibrinolytic
hemostatic role: von willebrand factor
coagulation
platelet adhesion
inhibits platelet adhesion and aggregation
stimulates vasodilation
prostacyclin (PGI2)
stimulates vasodilation
adenosine
destroys ADP and limits platelet activation
ADPase
endothelial cell receptor for thrombin, binding and inactivating ienhances fibrinolytic action of protein C in plasma
thrombomodulin
coats endothelial cell surface
enhances activity of anti thrombin III
heparan sulfate
converts plasminogen to plasmin
tissue plasminogen activator
regulatory protein for fibrinolytic system
plasminogen activator inhibitor-1
produced in endothelium and stored in endothelium
vWF
vWF is stored in the form of
Weibel Palade bodies
vWF attaches to
factor VIII: C
