Vascular and PLT Function Lecture 1 Flashcards
Describe Hemostasis
blood clotting to arrest bleeding and re-establish blood flow during the healing process
Has a balance
Involves vascular, plts, coag cascade, control, fibrinolysis
Primary Hemostasis Overview
Plt aggregation
WHITE THROMBUS
Secondary Hemostasis Overview
Fibrin Strands
RED THROMBUS
Hemathralgia
bleeding into joints
Purpura
Ecchymoses
Bruises
Epistaxis
nose bleed
DVT
abnormal clotting in deep veins such as the legs
Cryoprecipitate
substrate from human plasma can be transfused
Stages of hemostasis
Primary
role of blood vessels/plts at site forming plt plug
Vascular Parameter
Tunica Intama (Inner layer)
Broad flat enothelial cells
BM collagen
Prevents blood from reacting with other layers
Stages of hemostasis
Secondary
fibrin developes to stregnthen plts
Vascular Parameter
Tunica Media (middle)
elastic/smooth,
Constricts and dilates
Vascular Parameter
Tunica Adventia (outer)
connective/support tissue
Resistance to thrombosis formation
phy
p/n
synth by,
v
inhibits?
Physical barrier
Prostaglandin PG12/PG12 and Nitric Oxide
synth by endoth cells, vasodilator, inhibits plt adhesion
More about Resistance to thrombosis formation
involved in activity of?
inhibits?
what inhibits tissue factor?
involved in activity of protein C and Anti-thrombin, both inhibit factors of the cascade
TFPI inhibits tissue factor
When endothelial cells are disrupted
vaso…
Vasoconstriction - slows blood flow and sheer stress
Initial stimuli of hemostasis
PAF, TF III, Collagen
localize clot formation
what adhesion?
endo cells syth and release?
pts….secrete?
collagen plt adhesion
endo cells synth and release VON Williebrand Factor
(plts adhere, secretes ADAMS13, binding for IXA/XA)
provide activators for clearance of thrombus
to break down fibrin clot TPA
Endothelial cells play roles in both?
procoag and anticoag
Hematopoesis in the BM
plts apart of myeloid cell lines from HSC
Megakaryocyte —plt
TPO/ Thrombopoetin
regulates megakary production and plt release from BM in response to thrombocytopenia
Binds to receptors on plts
Inhibits megakary apoptosis
Increased Plts = DECREASE TPO = few megakaryocytes
Ultrastructure of plts
Peripheral Zone
Glycocalyx
mediates?
mediates plt adhesion and aggregation
(adhesion) plts stick to blood vessel
Aggreg - plt stick to plt
Ultrastructure of plts
Peripheral Zone
Open canalicular system
extension of plt membrane, winds down to interrior
Sol-Gel Zone of plts
Cytoskeleton
facilitates?
micro/cont
maintains shape, facilitates secretion process
microfilaments and contracticle proteins
Sol-Gel Zone of plts
Dense tubular system
plt activation and Ca++ storage
Organelle Zone of PLTS
Lysozomes/Mitochonrdria
lYSO - few, may disrupt endo structure after vasc.
Mito - ATP synth
Organelle Zone of Plts
Granules
Dense granules (ADP/CA++/Serotonin) larger and fewer in numbers
Alpha Granules (TXA2,VWF,FV,FVIII,FI,HMWK,PF4) more numerous
Thromboxane A2
plt activation and aggregation
ASPRIN inhibits cyclooxinganase and inhibits plt activation and aggregation
Plt function in vascular injury
Adhesion
sticking to
what is glue?
platelet receptor for VWF?
what does vwf carry?
sticking to collagen
collagen exposed
VWF is glue between collagen and plts
(plt receptor for VWF is GP IB)
VWF carries FVII
Plt function in vascular injury
Activation
shape…causes?
stim by agonists….what is formed from the plt?
Receptors?
initiated by plt adhesion induces a shape change which allows release of granules/secretion
stim by agonist - pseudopods w actin and myosin, glycoprot IIB/IIIA receptors
Plt function in vascular injury
Release reaction/secretion
S
V
A
T
C
F
plt adhere and are stim to secrete contents of granules
Serotonin: vasocontriction
VWF: plt adhesion
ADP plt aggregation
TXA2 plt aggregation
Ca: activates plts/cascade
Fibrinogen: plt aggregation/cascade
Plt function in vascular injury
Agreggation
what exposes GP IIB/IIIA complex?
recruits?
what attaches and makes a bridge? this causes?
ADP and TXA2 expose GP IIB/ IIIa complex
recruit more plts to site
fibrinogen attaches to plt membrane forming bridge, results in PLUG
Plt function in vascular injury
Clot retraction
actin and myosin contract, pulls everything back in stopping bleeding
PLT plug
provides foundation for clot form such as phospholipid PF3 (plt factor 3) “not a true facotr”
supports coag cascade
provides binding for vit K
Plt effectiveness
very young
what reverses activation of plts
more dependent on function than #
<50 x 103 may have prob w surgery
<10 x 103 spontaneous bleeds
very young plts may posses increased activity
PG12 reverses activation of plts
