Platelet Production, Structure, and Function Flashcards
responsible for the commitment of megakaryoblast further in more mature states
thrombopoeitin
normal value of platelets
150 - 400 x 10^9 L
megakaryocute progenitors arise from common myeloid progenitor under the transcription gene product
GATA-1
GATA 1 is regulated by this cofactor
FOG1
megakaryocyte differentiation is suppressed by gene product
MYB
last precursor cell capable of mitosis
CFU-meg
form of mitosis that lacks telophase and cytokinesis
endomitosis
endomitosis is initiated by the suppresion of ____ by the ___
Rho/ROCK signaling pathway
RUNX1
transcription factor that influences DNA production up to 32 N to produce abundant cytoplasm
NF- E2
series of stages where the cells can be recognized by their unique morphology
terminal differentiation
megakaryoblast percent
20
megakaryoblast size
14-18 um
megakaryoblast nucleus shape
round
megakaryoblast chromatin
homogenous
megakaryoblast: N:C ratio
3:1
megakaryoblast endomitosis
present
megakaryoblast cytoplasm
basophilic
promegakaryocyte percent
25
promegakaryocyte size
15 to 40 un
promegakaryocyte nucleus
indented
promegakaryocyte chromatin
moderately condensed
promegakaryocyte N:C ratio
1:2
promegakaryocyte endomitosis
ends
promegakaryocyte cytoplasm
basophilic and granular
megakaryocyte percent
55
megakaryocyte size
30 to 50 um
megakaryocyte nucleus
multilobed
megakaryocyte chromatin
deeply and variablt condensed
megakaryocyte N:C ratio
1:4
megakaryocyte endomitosis
absent
megakaryocyte cytoplasm
azurophilic and granular
membrane lined channeles that grow inward, subdivide the entire cytoplasm and delineates individual platelets
demarcation membrane system
identifiable characteristic of MK II
indentation at the 4N stage
identification characteristic of MK I
plasma blebs
a single.megakaryocyte may shed how many platelets
2000 to 4000
average thrombopoeisis per day
10^8 megakaryocytes producing 10^11 platelets
MPL
BFU Meg to platelets
CD34
BFU meg to LD CFU Meg
CD41
CFU Meg to platelet
CD42, PF4, VWF
terminal differentiation stages
TPO
differentiation to
progenitors
megakaryocytes
late maturation
IL 3
differentiation to progenitors and megakaryocytes
IL 6
late maturation and thrombopoeisis
IL 11
differentiation to megakaryocytes
late maturation
thrombopoeisis
4 major regions of the platelet
plasma membrane
submembrane area
sol gel zone
organelle zone
shape of platelets under homeostatic conditions
discoid
platelet glycocalyx thickness
40-50 nm
glycocalyx contains this glycoproteins
gp Ia Ib IIa IIb III IV V IX
facilitate platelet adhesion to vWF
gp Ib/ IX
facilitate platelet aggregation
gp IIb/ IIIa
plasma membrane contains
sodium potassium ATPase pump
factor VIII
phosphatidylserine,inositol,choline
functions of the submembrane area
regulate normal discoid shape
base for pseudopod formation
interact with contractile proteins to modulate adhesion and retraction
2 components of the sol gels or cytoskeleton zone
microtubules
microfilaments
direct contravtile response to stimulus
microtubules
contractile force that brings organelles to center during activation
microfilaments
two granules produced by platelets
alpha granules
dense granules
components of dense granules
adenosine diphosphate and triphosphates
guanosine diphosphates and triphosphates
calcium
magnesium
serotonin
alpha granules classification of content
- platelet specific proteins
- multimerin
- adhesive glycoproteins
- coagulation factors
- mitogenic factors
- fibrinolytic inhibitors
- membrane associated proteins
binds endogenously released heparin to counteract inhibitory effect
PF4
beta thromboglobulin
acts as a bridge between ADP stimulated platelets
fibrinogen
bind to platelet surface and in turn provide base for binding of other coagulation factors
factor V
stimulates smooth muscle cell growth and proliferation
platelet derived growth factor
endothelial cell growth factor
platelet specific proteins
PF4
beta thromboglobulin
large polymers of vWF
multimerin
adhesive glycoproteins
fibrinogen
fibronectin
vitronectin
vWF
coagulation factors
factor V
factor XI
protein S
mitogenic factors
PDGF
ECGF
TGFB
fibrinolytic inhibitors
alpha 2 plasmin inhibitor
plasminogen activator inhibitor
membrane associated proteins
P selctin
GMP 33
24-kd GTP binding protein
gpIV
osteonectin
4 coagulants secreted by platelets
high molecular weight kinin
fibrinogen
factor V
vWF
4 aggregators secreted by platelets
ADP
calcium
PF4
thrombospondin
promotes platelet aggregation
ADP and calcium
promotes platelet aggregation and inhibits heparin
PF4
thrombospondin
2 vasoconstrictors released by the platelet
serotonithromboxane A2
vasoconstriction
serotonin
vasoconstriction and platelet release reaction
thromboxane A2 precursor
2 substances secreted for vascular repair
PDGF
beta thronboglobulin
promotes smooth muscle growth
PDGF
chemotactic factor for fibroblast and heparin inhibitor
beta thromboglobulin
1 fibrinolytic substance secreted by platelet
plasminogen
plasmin precursor
plasminogen
4 inhibitors secreted by platelets
alpha 2 antiplasmin
protease nexin II
PIXI
C1 esterase inhibitor
plasmin inhibitor, inhibits clot lysis
alpha 2 antiplasmin
inhibits factor XIa thereby activating factor IX
protease nexin II and PIXI
factors that affect platelet adhesion
extent and depth of vessel injury
type of collagen exposed
shear rate
increased level of other plasma proteins
produced by endothelial lining and only causes platelet adhesion
type IV and V collagen
produced by smooth kuscle cells and induce platelet adhesion, release reaction and aggregation
collagen type I and III
if platelets are turbulent, they have a
high shear rate
if platelet flow is laminar and unidirectional it has a
low shear rate
examples of proteins that may be increased that may indice platelet aggregation
albumin and fibrinogen in artificial surfaces
protein M in rheumatic fever
stimuli to platelet aggregation
ADP
thrombin
thromboxane A2
collagen
epinephrine
independent mediators of platelet aggregation
ADP
thrombin
Thromboxane A2
ADP causes
TXA2 release
platelet aggregation
TXA2 release causes
vasoconstriction
platelet aggregation
theombin release causes
ADP release
Thrombixane A2 synthesis
explain TXA2 synthesis
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