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Clin Path > Platelets and Coagulation > Flashcards

Platelets and Coagulation Flashcards

1
Q

What is the maturation process of Megakaryocyte?

A

PPSC-myeloid stem cell-megakaryoblast-megakaryocyte

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2
Q

What is Thrombopoietin?

A

stimuli for PPSC’s to differentiate into megakaryocyte

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3
Q

What is the source of TPO?

A

uncertain but involves liver, endothelial cells and fibroblasts

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4
Q

What signals the release of platelets to increase amount in blood?

A

negative feedback

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5
Q

What is Endomitosis?

A

nucleus divides inside itself

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6
Q

What is the Platelet Parent Cell?

A

megakaryocyte

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7
Q

What is the result of Endomitosis?

A

large, multinucleated cell with abundant cytoplasm (nuclei fuse together resembling one large, multilobed nucleus)

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8
Q

Where do most Megakaryocyes reside?

A

bone marrow

but some colonize the lungs and produce platelets

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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

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10
Q

How many platelts form from 1 megakaryocyte?

A

1,000-5,000

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11
Q

Where are platelets stored?

A

spleen

released as needed

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12
Q

How long do platelets circulate in the blood before being destroyed by macrophages (dogs)?

A

5-8 days

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13
Q

What is the concentration in blood?

A

RBCs>PLTs>WBCs

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14
Q

True or False: Platelets have a greater variety of functions than any of the true blood cells

A

True

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15
Q

Platelets are (bigger or smaller) compared to a RBC

A

smaller

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16
Q

What animal’s platelets stain lighter than others?

A

horses

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17
Q

How long do platelets circulate in cats?

A

1 day

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18
Q

What shape are platelets while in circulation?

A

discoid

have numerous, small, purple/pink granules scattered throughout the cytoplasm

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19
Q

What kind of platelets are occasionally seen in blood smears?

A

giant platelets

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20
Q

What happens to a platelet when it becomes activated?

A

centralization of granules

develop dendritic processes

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21
Q

What is the normal range in dogs?

A

200,000-500,000

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22
Q

What is the normal range in cats?

A

300,000-700,000

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23
Q

What is the normal range for all species?

A

100,000-800,000

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24
Q

What is the concentration of platelets in horses?

A

lowest normal concentration

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25
Q

What is the concentration of platelets in cattle?

A

highest normal concentration

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26
Q

When will animals bleed spontaneously?

A

if platelet concentration is less than 10,000-50,000

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27
Q

What do 90% of all bleeding disorders result from?

A

abnormalitites in platelet number or function

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28
Q

What is an adequate number of platelets to see during a differential count?

A

8-10/hpf

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29
Q

What should you do if it appears that the # of platelets on a blood film is decreased

A

perform a manual platelet count

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30
Q

Where should you check for platelet clumps during a manual platelet count?

A

body of smear
feathered edge
blood tube

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31
Q

When can platelet clumping occur?

A

common in cats
result of needle stick to draw blood
can occur in-vitro (low ratio of anticoagulant to blood)

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32
Q

How do you perform a platelet estimation?

A 
using hemocytometer (acetic acid)
count during blood film evaluation
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33
Q

What are the 2 methods of Platelet Estimation?

A

direct

indirect

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34
Q

Direct Method of Platelet Estimation

A

count 10 HPFs and determine the average (7-21=adequate), multiply by 20,000 to determine the estimated # of platelets per microliter

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35
Q

Indirect Method of Platelet Estimation

A

while performin differential count, keep track of platelet # then divide by 100. Multiply by total WBC count to determine total # of platelets

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36
Q

What are the primary functions of platelets?

A 
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
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37
Q

Maintenance of Vascular Integrity

A

line endothelium of vascular system and release endothelial growth factor into endothelial cells

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38
Q

What vasoconstrictor is secreted by platelets?

A

thromboxane

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39
Q

What initiates the formation of a platelet plug?

A

damaged blood vessel

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40
Q

What procoagulants are secreted by platelets?

A

Factors XII and XIII, PF1, PF2, PF3, PF4

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41
Q

What is PDGF?

A

platelet derived growth factor
stimulates fibroblasts and smooth muscle to multiply and repair damaged vessels (and strengthen and seal vessel while repairs take place)

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42
Q

What is fibrinolysis?

A

dissolution of blood clots

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43
Q

What does fibrinolysis stimulate?

A

secretion of tissue plasminogen activator(TPA) which converts plasminogen to plasmin

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44
Q

What is Hemostasis?

A

arrest/stoppage of blood loss from vessels

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45
Q

What is the process of Hemostasis dependent upon?

A

integrity of blood vessels
adequate # of normal circulating platelets
presence of adequate coagulation factors

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46
Q

Why is the liver essential to coagulation?

A

synthesizes clotting factors

produces bile which is essential for utilization of vitmin k

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47
Q

Which factors require vitamin K for activation?

A

Factors II, VII, IX, X

48
Q

What are the 3 stages of Hemostasis?

A

primary
secondary
tertiary

49
Q

What are the stages of Primary Hemostasis?

A

vasoconstriction
platelet adhesion
platelet aggregation

50
Q

What happens during Platelet Adhesion?

A

platelets attach to exposed endothelial lining (due to positive charge)

51
Q

What prevents platelets from sticking to normal endothelium?

A

negative charge

prostacyclin

52
Q

What factor is necessary to bind platelets?

A

vonwillebrands factor

53
Q

What synthesizes VonWillebrand’s factor?

A

megakaryotes and endothelial cells

54
Q

What happens during Platelet Aggregation?

A

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
Q

What are the steps during Secondary Hemostasis?

A 
coagulation factors (protein) are activated 
includes intrinsic, extrinsic and common pathways
56
Q

What is the ultimate goal of Primary Hemostasis?

A

formation of platelet plug

57
Q

What is the ultimate goal of Secondary Hemostasis?

A

fibrin formation

58
Q

What is the Extrensic Pathway?

A

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
Q

What is the Intrinsic Pathway?

A

triggered by effects of abnormal surfaces on components normally present in blood

60
Q

What are the steps during the Tertiary Hemostasis?

A

clot retraction occurs after 30 minutes
PDGF secreted to initate tissue repair
TPA converts plasminogen to plasmin to initiate clot dissolution

61
Q

What is Coagulopathy?

A

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
Q

What is Genetic Coagulopathy?

A

inherited/congenital
manifest at young age
usually associated with a SINGLE coagulation factor

63
Q

What is Aquired Coagulopathy?

A

may occur at any age

often involve MULTIPLE coagulation factors

64
Q

How are Coagulopathies categorized?

A

according to the stage of hemostasis that they affect

65
Q

When should you suspect a Hemostatic Disorder?

A

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
Q

What are the types of Defects of Primary Hemostasis?

A

quantative

qualitive

67
Q

What are the types of Quantative defects of primary hemostasis?

A

thrombocytopenia

thrombocytosis

68
Q

What are causes of Thrombocytopenia?

A

decreased production
increased rate of destruction
activation/utiliaztion
consumption/sequesterization

69
Q

What are the most common infectious diseases that cause Thrombocytopenia?

A 
ehrlichiosis
toxoplasmosis
FeLV
haemobartonellosis
FIV
FIP
70
Q

What are the causes of Thrombocytosis?

A

bone marrow disorders
disorders secondary to disease states
splenic contractions

71
Q

What are the types of Qualitative defects of primary hemostasis?

A

vonwillebrand disease
thrombocytopathy
vascular causes of bleeding

72
Q

True or False: vWF is a congenital Hemostatic condition

A

True

73
Q

Decreased or Deficient vWF=

A

decreased platelet adhesion, decreased aggregation

74
Q

What are clinical signs of VonWillebrand’s disease?

A

mucus membran hemorrhage
hematuria
GI bleeding
epistaxis

75
Q

What breeds are predisposed to VonWillebrand’s disease?

A 
doberman pinscher #1
german shepherd dog
golden retriever
chesapeake bay retriever
poodle
welsh corgi
76
Q

What is Thrombocytopathy?

A

disease of platelets

77
Q

What does Thrombocytopathy result from?

A

defective granules

78
Q

True or False: Thrombocytopathy can be congenital or aquired

A

True

79
Q

What are the causes of Thrombocytopathy?

A

1-NSAIDs

myeloproliferative disorders
rare congenital diseases

80
Q

What are the reasons for aquired Vascular bleeding?

A

scurvy

Cushing’s

81
Q

What are the reasons for congenital Vascular bleeding?

A

Ehlers-Danlos syndrome

Marfan Syndrome

82
Q

What are clinical signs associated with Primary Hemostasis?

A 
chronic bleeding
prolonged bleeding
petechiae
purpura
ecchymoses
epistaxis
melena
83
Q

What are clinical signs of Secondary Hemostasis?

A

delayed bleeding
rebleeding
hemorrhaging into body cavities
hematoma formation

84
Q

What are the 2 types of Secondary Hemostasis?

A

congenital

aquired

85
Q

What is Congenital Secondary Hemostasis?

A

congenital clotting factor deficiencies of virtually all known coagulation factors have been described

86
Q

What are the types of Aquired Secondary Hemostasis?

A

rodenticide toxicity
hepatic disease
DIC

87
Q

What are the common active ingredients of rat poision?

A

coumarin
dicoumarol
warfarin

88
Q

What clotting factors does the liver synthesize?

A

I, II, V, VII, VIII, IX, X, XI, XII

89
Q

What is Disseminated Intravascular Coagulopathy?

A

syndrome that results from a pathologic condition that involves accelerated activation of plaatelets, coagulation proteins and plasmin

90
Q

What are conditions associated with DIC?

A 
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
Q

What are the 3 phases of DIC?

A 
peracute phase (hypercoaguable)
acute phase (consumptive)
chronic phase
92
Q

What are the c/s of Peracute Phase?

A

may have few or no overt CS

93
Q

What are the c/s of the Acute Phase

A

venipuncture oozing
modest to severe hemorrhage
absolute inability to form a clot

94
Q

What are c/s of Chronic Phase?

A

if animal survives=chronic

no c/s of oozing blood

95
Q

What kind of prognosis does DIC have?

A

grim

96
Q

What is the treatment for DIC?

A

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
Q

What are defects of Tertiary Hemostasis?

A

uncommon
excessive fibrinolysis
fibrinolysis

98
Q

What starts the Extrinsic Pathway?

A

when blood contacts tissue debris or damage

99
Q

Extrinsic Pathway

A

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
Q

What starts the Intrinsic Pathway?

A

blood contacting abnormal surfaces

101
Q

Intrinsic Pathway

A

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
Q

Thromboplastin

A

factor III
“tissue factor”
when comes in contact with blood, becomes activated

103
Q

Proconvertin

A

factor VII
“stable factor”
enzyme

104
Q

Hageman Factor

A

factor XII

located inside platelet granules

105
Q

PTA Factor

A

factor XI

106
Q

Christmas Factor

A

factor IX

107
Q

Antihemophiilic Factor

A

factor XIII

108
Q

Stuart-Prower Factor

A

factor X

109
Q

Prothrombin Activator

A

only happens when labile factor is present, F3, Ca

110
Q

Prothrombin

A

factor II

globulin

111
Q

Thrombin

A

factor IIa

112
Q

Fibrinogen

A

factor I

113
Q

Fibrin

A

factor Ia

114
Q

Fibrin Stabilizing Factor

A

factor XIII

115
Q

Labile Factor

A

factor V

Clin Path (8 decks)

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