Platelets and Coagulation Flashcards
1
Q
What is the maturation process of Megakaryocyte?
A
PPSC-myeloid stem cell-megakaryoblast-megakaryocyte
2
Q
What is Thrombopoietin?
A
stimuli for PPSC’s to differentiate into megakaryocyte
3
Q
What is the source of TPO?
A
uncertain but involves liver, endothelial cells and fibroblasts
4
Q
What signals the release of platelets to increase amount in blood?
A
negative feedback
5
Q
What is Endomitosis?
A
nucleus divides inside itself
6
Q
What is the Platelet Parent Cell?
A
megakaryocyte
7
Q
What is the result of Endomitosis?
A
large, multinucleated cell with abundant cytoplasm (nuclei fuse together resembling one large, multilobed nucleus)
8
Q
Where do most Megakaryocyes reside?
A
bone marrow
but some colonize the lungs and produce platelets
9
Q
What are Invaginations?
A
infoldings that develop into plasma membrane that divide marginal cytoplasm into little compartments which break off and enter bloodstream as platelets
10
Q
How many platelts form from 1 megakaryocyte?
A
1,000-5,000
11
Q
Where are platelets stored?
A
spleen
released as needed
12
Q
How long do platelets circulate in the blood before being destroyed by macrophages (dogs)?
A
5-8 days
13
Q
What is the concentration in blood?
A
RBCs>PLTs>WBCs
14
Q
True or False: Platelets have a greater variety of functions than any of the true blood cells
A
True
15
Q
Platelets are (bigger or smaller) compared to a RBC
A
smaller
16
Q
What animal’s platelets stain lighter than others?
A
horses
17
Q
How long do platelets circulate in cats?
A
1 day
18
Q
What shape are platelets while in circulation?
A
discoid
have numerous, small, purple/pink granules scattered throughout the cytoplasm
19
Q
What kind of platelets are occasionally seen in blood smears?
A
giant platelets
20
Q
What happens to a platelet when it becomes activated?
A
centralization of granules
develop dendritic processes
21
Q
What is the normal range in dogs?
A
200,000-500,000
22
Q
What is the normal range in cats?
A
300,000-700,000
23
Q
What is the normal range for all species?
A
100,000-800,000
24
Q
What is the concentration of platelets in horses?
A
lowest normal concentration
25
What is the concentration of platelets in cattle?
highest normal concentration
26
When will animals bleed spontaneously?
if platelet concentration is less than 10,000-50,000
27
What do 90% of all bleeding disorders result from?
abnormalitites in platelet number or function
28
What is an adequate number of platelets to see during a differential count?
8-10/hpf
29
What should you do if it appears that the # of platelets on a blood film is decreased
perform a manual platelet count
30
Where should you check for platelet clumps during a manual platelet count?
body of smear
feathered edge
blood tube
31
When can platelet clumping occur?
common in cats
result of needle stick to draw blood
can occur in-vitro (low ratio of anticoagulant to blood)
32
How do you perform a platelet estimation?
```
using hemocytometer (acetic acid)
count during blood film evaluation
```
33
What are the 2 methods of Platelet Estimation?
direct
| indirect
34
Direct Method of Platelet Estimation
count 10 HPFs and determine the average (7-21=adequate), multiply by 20,000 to determine the estimated # of platelets per microliter
35
Indirect Method of Platelet Estimation
while performin differential count, keep track of platelet # then divide by 100. Multiply by total WBC count to determine total # of platelets
36
What are the primary functions of platelets?
```
maintenance of vascular integrity
secrete vasoconstrictors
platelet plug formation
secrete procoagulants and calcium
secrete growth factors to help repair damaged vessels
initiate fibrinolysis
secrete cytokines that attract neutrophils and monocytes to sites of inflammation
limited role in phagocytosis
```
37
Maintenance of Vascular Integrity
line endothelium of vascular system and release endothelial growth factor into endothelial cells
38
What vasoconstrictor is secreted by platelets?
thromboxane
39
What initiates the formation of a platelet plug?
damaged blood vessel
40
What procoagulants are secreted by platelets?
Factors XII and XIII, PF1, PF2, PF3, PF4
41
What is PDGF?
platelet derived growth factor
stimulates fibroblasts and smooth muscle to multiply and repair damaged vessels (and strengthen and seal vessel while repairs take place)
42
What is fibrinolysis?
dissolution of blood clots
43
What does fibrinolysis stimulate?
secretion of tissue plasminogen activator(TPA) which converts plasminogen to plasmin
44
What is Hemostasis?
arrest/stoppage of blood loss from vessels
45
What is the process of Hemostasis dependent upon?
integrity of blood vessels
adequate # of normal circulating platelets
presence of adequate coagulation factors
46
Why is the liver essential to coagulation?
synthesizes clotting factors
| produces bile which is essential for utilization of vitmin k
47
Which factors require vitamin K for activation?
Factors II, VII, IX, X
48
What are the 3 stages of Hemostasis?
primary
secondary
tertiary
49
What are the stages of Primary Hemostasis?
vasoconstriction
platelet adhesion
platelet aggregation
50
What happens during Platelet Adhesion?
platelets attach to exposed endothelial lining (due to positive charge)
51
What prevents platelets from sticking to normal endothelium?
negative charge
| prostacyclin
52
What factor is necessary to bind platelets?
vonwillebrands factor
53
What synthesizes VonWillebrand's factor?
megakaryotes and endothelial cells
54
What happens during Platelet Aggregation?
as platelets adhere to one another, they continue to change physically to promote increased aggregation
granules are released
other platelets are attracted to site by chemicals released to site by chemicals released from platelet granules
55
What are the steps during Secondary Hemostasis?
```
coagulation factors (protein) are activated
includes intrinsic, extrinsic and common pathways
```
56
What is the ultimate goal of Primary Hemostasis?
formation of platelet plug
57
What is the ultimate goal of Secondary Hemostasis?
fibrin formation
58
What is the Extrensic Pathway?
occurs outside vessel wall when shed blood contacts tissue debris. Factor 3 is embedded in plasma membrane of most cells and is released by trauma to the endothelium
59
What is the Intrinsic Pathway?
triggered by effects of abnormal surfaces on components normally present in blood
60
What are the steps during the Tertiary Hemostasis?
clot retraction occurs after 30 minutes
PDGF secreted to initate tissue repair
TPA converts plasminogen to plasmin to initiate clot dissolution
61
What is Coagulopathy?
any disorder of blood coagulation (bleeding diathesis/tendency)
may involve defects or deficits in vasculature, platelets or clotting factors
can be aquired or genetic
62
What is Genetic Coagulopathy?
inherited/congenital
manifest at young age
usually associated with a SINGLE coagulation factor
63
What is Aquired Coagulopathy?
may occur at any age
| often involve MULTIPLE coagulation factors
64
How are Coagulopathies categorized?
according to the stage of hemostasis that they affect
65
When should you suspect a Hemostatic Disorder?
increased length of bleeding time after venipuncture
evidence of intra/subdermal bleeding or bleeding into body cavities, joints, etc.
family history of diathesis
history of prolonged bleeding
66
What are the types of Defects of Primary Hemostasis?
quantative
| qualitive
67
What are the types of Quantative defects of primary hemostasis?
thrombocytopenia
| thrombocytosis
68
What are causes of Thrombocytopenia?
decreased production
increased rate of destruction
activation/utiliaztion
consumption/sequesterization
69
What are the most common infectious diseases that cause Thrombocytopenia?
```
ehrlichiosis
toxoplasmosis
FeLV
haemobartonellosis
FIV
FIP
```
70
What are the causes of Thrombocytosis?
bone marrow disorders
disorders secondary to disease states
splenic contractions
71
What are the types of Qualitative defects of primary hemostasis?
vonwillebrand disease
thrombocytopathy
vascular causes of bleeding
72
True or False: vWF is a congenital Hemostatic condition
True
73
Decreased or Deficient vWF=
decreased platelet adhesion, decreased aggregation
74
What are clinical signs of VonWillebrand's disease?
mucus membran hemorrhage
hematuria
GI bleeding
epistaxis
75
What breeds are predisposed to VonWillebrand's disease?
```
doberman pinscher #1
german shepherd dog
golden retriever
chesapeake bay retriever
poodle
welsh corgi
```
76
What is Thrombocytopathy?
disease of platelets
77
What does Thrombocytopathy result from?
defective granules
78
True or False: Thrombocytopathy can be congenital or aquired
True
79
What are the causes of Thrombocytopathy?
#1-NSAIDs
myeloproliferative disorders
rare congenital diseases
80
What are the reasons for aquired Vascular bleeding?
scurvy
| Cushing's
81
What are the reasons for congenital Vascular bleeding?
Ehlers-Danlos syndrome
| Marfan Syndrome
82
What are clinical signs associated with Primary Hemostasis?
```
chronic bleeding
prolonged bleeding
petechiae
purpura
ecchymoses
epistaxis
melena
```
83
What are clinical signs of Secondary Hemostasis?
delayed bleeding
rebleeding
hemorrhaging into body cavities
hematoma formation
84
What are the 2 types of Secondary Hemostasis?
congenital
| aquired
85
What is Congenital Secondary Hemostasis?
congenital clotting factor deficiencies of virtually all known coagulation factors have been described
86
What are the types of Aquired Secondary Hemostasis?
rodenticide toxicity
hepatic disease
DIC
87
What are the common active ingredients of rat poision?
coumarin
dicoumarol
warfarin
88
What clotting factors does the liver synthesize?
I, II, V, VII, VIII, IX, X, XI, XII
89
What is Disseminated Intravascular Coagulopathy?
syndrome that results from a pathologic condition that involves accelerated activation of plaatelets, coagulation proteins and plasmin
90
What are conditions associated with DIC?
```
systemic infections (septicemia, endotoxemia)
pancreatitis
trauma (systemic inflammatory response syndrome)
infectious diseases
burns
severe shock
neoplasia (exposes subendothelial collagen)
envenomation (activates factor X)
heatstroke
heartworm disease
secondary to hepatic disease
sometimes considered idiopathic
```
91
What are the 3 phases of DIC?
```
peracute phase (hypercoaguable)
acute phase (consumptive)
chronic phase
```
92
What are the c/s of Peracute Phase?
may have few or no overt CS
93
What are the c/s of the Acute Phase
venipuncture oozing
modest to severe hemorrhage
absolute inability to form a clot
94
What are c/s of Chronic Phase?
if animal survives=chronic
| no c/s of oozing blood
95
What kind of prognosis does DIC have?
grim
96
What is the treatment for DIC?
supportive care (target organs where microemboli may cause ischemia)
fluid therapy (balanced electrolyte solutions IV to maintain effective circulating blod volume)
coagulation factor replacement (transfusion with heparin rich fluid)
administration of IV heparin
close monitoring
97
What are defects of Tertiary Hemostasis?
uncommon
excessive fibrinolysis
fibrinolysis
98
What starts the Extrinsic Pathway?
when blood contacts tissue debris or damage
99
Extrinsic Pathway
damage occurs outside vessel wall-> (releases) thromboplastin->(activates) proconvertin->(activates) stuart-prower factor->(activates) prothrombin activator (with labile factor)-> (converts) prothrombin->(into) thrombin->(converts) fibrinogen->(into) fibrin->fibrin clot <- fibrin stabilizing factor
100
What starts the Intrinsic Pathway?
blood contacting abnormal surfaces
101
Intrinsic Pathway
damage occurs inside vessel wall-> (activates) hageman factor->(activates) PTA factor->(activates) christmas factor->(activates) antihemophilic factor->(activates)stuart-prower factor->(activates) prothrombin activator (with labile factor)-> (converts) prothrombin->(into) thrombin->(converts) fibrinogen->(into) fibrin->fibrin clot <- fibrin stabilizing factor
102
Thromboplastin
factor III
"tissue factor"
when comes in contact with blood, becomes activated
103
Proconvertin
factor VII
"stable factor"
enzyme
104
Hageman Factor
factor XII
| located inside platelet granules
105
PTA Factor
factor XI
106
Christmas Factor
factor IX
107
Antihemophiilic Factor
factor XIII
108
Stuart-Prower Factor
factor X
109
Prothrombin Activator
only happens when labile factor is present, F3, Ca
110
Prothrombin
factor II
| globulin
111
Thrombin
factor IIa
112
Fibrinogen
factor I
113
Fibrin
factor Ia
114
Fibrin Stabilizing Factor
factor XIII
115
Labile Factor
factor V
