Homeostasis and Platelet Disorders Flashcards
(180 cards)
0
Q
What does “hemo” mean?
A
Blood
1
Q
The stoppage of blood is known as what?
A
Hemostasis
2
Q
What does “stasis” mean?
A
Stop
3
Q
To achieve hemostasis without obstructing blood flow is what?
A
The goal.
4
Q
Formation of a thrombus leads to what?
A
A blood clot
5
Q
Hemostasis involves the interaction of what 3 components?
A
- Blood vessels
- Platelets
- Coagulation factors
6
Q
After injury to a blood vessel, what 3 steps are seen?
A
- Vessel constriction
- Platelet adhesion (primary hemostasis)
- Activation of coagulation (secondary hemostasis)
7
Q
What can thrombosis inhibit?
A
Blood loss/consumption
8
Q
What can cause thrombosis?
A
Increased procoagulant activity
9
Q
What are 3 causes hemorrhage?
A
- Decreased procoagulant activity
- Thrombocytosis (decreased platelet function)
- Excessive fibrinolysis
10
Q
The secondary hemostatic plug is also known as what?
A
Definitive fibrin plug
11
Q
What is the average size of a platelet?
A
2-4 um
12
Q
Do platelets have a nucleus?
A
No
13
Q
What are 3 things that can be found in a platelet?
A
- Cytoskeleton
- Alpha and dense granules
- Canalicular and tubular systems
14
Q
What act as receptors for ligands on platelets?
A
Membrane glycoproteins
15
Q
What are suggestive of increased platelet production?
A
Large and giant platelets
16
Q
What is the process of thrombopoiesis?
A
- Stem cell
- Megakaryoblast
- Megakaryocyte
- Platelets
17
Q
What type of a nucleus do megakaryocytes have?
A
Polyploid nucleus (8N-64N)
18
Q
Are megakaryocytes small or large cells?
A
Large cells
19
Q
Do megakaryotes have abundant cytoplasm?
A
Yes
20
Q
Where are megakaryocytes located?
A
At the sinus
21
Q
What do megakaryocytes break into?
A
Individual platelets
22
Q
What is the maturation time of Megakaryoblast to platelet release?
A
4-5 days
23
Q
What is thrombopoiesis regulated by?
A
Thrombopoietin (TPO)
24
What does Thrombopoietin stimulate?
Increased megakaryocyte production and differentiation.
25
Where are 3 places where thrombopoietin is continually produced?
- Liver
- Basement membrane
- Endothelium
26
A decrease in platelet numbers leads to what?
Increased free plasma TPO
27
What are 2 effects of an increase in free plasma TPO?
- Increase number , size and ploidy of megakaryocytes
| - Decrease in megakaryocyte maturation time.
28
What is the average life span of a platelet?
| In what species is this time shorter?
- About 5-10 days
| - Shorter in cats.
29
Where can you find about 1/3 of the platelet mass?
In the spleen.
30
What are 3 functions of platelets?
- Increase metabolic activity
- Primary Hemostasis
- Support secondary hemostasis
31
Formation of a primary hemostatic plug takes about how long?
3-5 minutes
32
What do platelets adhere to during primary hemostatic plug formation?
Subendothelium
33
What are the 4 steps of primary hemostatic plug formation?
- Adhere
- Activation
- Secrete
- Aggregate
34
What happens to the platelets during the activation stage of the primary hemostatic plug formation?
They change shape.
35
What do platelets secrete during primary hemostatic plug formation?
Their granules.
36
When platelets aggregate, what do they form?
A platelet plug.
37
What are 4 components required during the adhesion stage of primary hemostasis?
- von Willebrand Factor (vWF)
- ADP
- CA2+
- Serotonin
38
What are 2 functions of von Willebrand Factor (vWF)?
- Binds to GPlb on platelet surface.
| - Bridge between platelets and collagen.
39
How do the shapes of platelets change during the activation stage of primary hemostasis?
From smooth discs to spheres with many filapodia.
40
Change in platelet shape occurs in response to what?
Thrombin
41
How does the platelet shape change affect surface area seen in primary hemostasis?
Increases the surface area.
42
What are 3 things that are secreted by platelets during the activation stage of primary hemostasis?
- Factors V and VIII
- Thromboxane A2
- Calcium (Ca2+)
43
The secretion of granule products by platelets seen during the activation stage of primary hemostasis can what 4 effects?
- Recruit more platelets
- Further platelet activation
- Facilitate coagulation
- Mediate vessel repair
44
Platelets carry a negative charge on their outer membrane surface during what stage of primary hemostasis?
Activation
45
Is platelet aggregation during primary hemostasis a reversible or irreversible process?
Irreversible process
46
What binds activated platelets and bridges adjacent platelets during aggregation of primary hemostasis?
Fibrinogen
47
What is required for the aggregation stage of primary hemostasis?
Ca2+
48
What is the end result of primary hemostasis?
Platelet plug formation
49
Platelets provide a surface for what during primary hemostasis?
Formation and deposition of fibrin.
50
How do clots contract?
Via actinomyosin filaments
51
What are 2 things clot retraction facilitates?
- Wound closure
| - Vessel patency
52
Platelet chemotaxis enhances what?
Neutrophil function.
53
Do platelets have antimicrobial activity?
Yes
54
Platelets are sources of what 3 factors of inflammation?
- Inflammatory mediators
- Vasoactive substances
- Mitogenic agents
55
What are 2 ways to test platelet concentration and morphology (size)?
- Blood smear
| - Hematology analyzers
56
What are 2 ways to test platelet function?
- Bleeding time tests
| - Specific platelet function tests
57
What is a way to test platelet production?
Bone marrow aspirate (BMA)
58
What are 2 ways to test for anti-platelet antibodies?
- Platelet surface-associated immunoglobulin (PSAIg)
| - Immunofluorescent antimegakaryocytic antibody test
59
To test for platelet concentration in blood, the blood should be collected in what type of tube?
Purple top - EDTA tube
60
What technique is the most important with drawing blood for the platelet concentration tests?
Venipuncture
61
When analyzing a blood smear for platelet concentration, about how many platelets are normally seen per high power field (100x)?
What is the minimum for horses?
- 7-10 platelets per field
| - Minimum of 4-7 platelets per field
62
When examining a blood smear for platelet counts, you should check for clumps, especially with what 2 species?
- Cats
| - Cattle
63
In general, are platelets smaller or larger than RBCs?
Smaller
64
More size variation of platelets is seen in what species?
Cats
65
Pale-staining platelets can be seen in what species?
Horses
66
What does increased numbers of enlarged platelets suggest?
Active production of platelets.
67
When the platelet count is lower than the lower end of the reference interval (LRI), what condition exists?
Thrombocytopenia
68
When the platelet count is greater than the upper reference interval (URI), what condition is present?
Thrombocytosis
69
You may see spontaneous hemorrhage when platelet counts are below what level?
20,000/uL
70
What does MPV stand for?
Mean platelet volume
71
What does increased MPV suggest?
Increased thrombopoiesis
72
Platelet function bleeding tests test the ability of platelets to do what?
Form a platelet plug.
73
Do platelet function bleeding tests test fibrin plug formation?
No
74
What does BMBT stand for?
Buccal mucosal bleeding time
75
What are the 3 steps of testing platelet function using BMBT?
- Make a standardized incision
- Blot blood gently
- Measure time for bleeding to cease
76
What is normal buccal mucosal bleeding time (BMBT) for dogs?
For cats?
For horses/cattle?
- Dogs: 1-5 minutes
- Cats: 1-3.5 minutes
- Horses/cattle: 8-10 minutes
77
What are the 3 steps of the cuticle (toenail) bleeding time test?
- Use a guillotine clipper and sever apex of nail
- Blot blood gently
- Measure time for bleeding to cease
78
What is the normal cuticle (toenail) bleeding time for dogs?
2-8 minutes
79
What are 3 examples of specific platelet function tests that require special equipment?
- Adhesion
- Aggregation
- Secretion
80
What does BMA stand for?
| What is it used to evaluate?
- Bone marrow aspirate
| - Megakaryocyte number and morphology
81
Why are platelet surface-associated immunoglobulin tests difficult to perform?
Platelets normally carry some immunoglobulin.
82
What does the immunofluorescent antimegakaryocytic antibody test detect?
Antibodies on Megakaryocytes
83
Is thrombocytopenia a specific disease?
No
84
What are 5 clinical features seen with thrombocytopenia?
- Mucosal bleeding
- Petechiation
- Ecchymosis
- Spontaneous hemorrhage with platelets counts below 20,000/uL
- May or may not have hemorrhagic anemia
85
What are 6 possible mechanisms behind of thrombocytopenia?
- Loss
- Consumption
- Destruction
- Decreased production
- Abnormal distribution
- Pseudothromboctopenia
86
Does hemorrhage alone usually cause significant thrombocytopenia?
What is an exception?
- No
| - Acute severe hemorrhage may result in mild thrombocytopenia
87
What is a possible cause of consumption of platelets?
Utilization of platelets during coagulation.
88
What are 3 possible causes of thrombocytopenia by consumption?
- Disseminated intravascular coagulation (DIC)
- Vasculitis (rickettsial disease, FIP)
- Viral infection
89
What range of degree of thrombocytopenia can be seen with consumption?
Mild to moderate
90
Coagulation defects (DIC) or leakage of blood from vessels (vasculitis) can lead to what?
Hemorrhage
91
What are 2 examples of destruction thrombocytopenia?
- Immune-mediated thrombocytopenia (ITP)
| - Alloimmune thrombocytopenia
92
Primary Immune-mediated thrombocytopenia is often what?
Idiopathic
93
What are 4 examples of causes of secondary immune-mediated thrombocytopenia?
- Drugs
- Viruses
- Sepsis
- Neoplasia
94
Alloimmune thrombocytopenia can be seen in what 2 species?
- Piglets
| - Foals
95
What does the dam produce with alloimmune thrombocytopenia?
Anti-platelet antibody from a previous pregnancy.
96
What do the offspring ingest with alloimmune thrombocytopenia?
Antibody in the colostrum.
97
Piglets with alloimmune thrombocytopenia have a high mortality rate from what?
Hemorrhage
98
What type of vaccination may induce an immune response against the platelets, leading to platelet aggregation and clearance?
Modified-live virus vaccination
99
Thrombocytopenia due to vaccination usually occurs when?
3-10 days post-vaccination
100
Is thrombocytopenia seen with vaccines usually mild or severe?
Mild
101
A complete blood count (CBC) can detect what type of thrombocytopenia?
Severe thrombocytopenia
102
Bone marrow aspirates are used to detect what?
Increased megakaryocytes (immature & mature)
103
What are 3 possible causes of decreased production of platelets?
- Bone marrow hypoplasia
- Neoplasia
- Myelonecrosis or myelofibrosis
104
The degree of thrombocytopenia seen with decreased production depends on what?
Extent of bone marrow disease.
105
What is the most common form of abnormal distribution of platelets?
Sequestration of platelets in large vascular beds.
106
What level of thrombocytopenia is seen with abnormal distribution of platelets?
Mild to moderate thrombocytopenia
107
What are 2 possible reason an analyzer might not measure platelets, leading to pseudothrombocytopenia?
- Too big (macrothrombocytes)
| - Clumped
108
An increased concentration of platelets is known as what?
Thrombocytosis
109
What are 2 major mechanisms of thrombocytosis?
- Increased production
| - Increased distribution in plasma
110
What type of symptoms are usually seen in animals with an increased platelet count?
Animals are usually asymptomatic.
111
What are 2 possible reasons for increased concentration of platelets?
Which one is more common?
- Primary neoplastic production of platelets
| - Secondary or reactive thrombocytosis (more common)
112
What are 5 possible causes of secondary or reactive thrombocytosis?
Which is the most common?
- Chronic inflammatory disease (most common)
- Iron deficiency anemia
- Chronic hemorrhage
- IMHA
- Some neoplasms
113
Increased concentration of platelets can be associated with what 4 situations?
- Rebound from thrombocytopenia
- Post-splenectomy
- Response to some drugs (vincristine)
- Excitement and exercise (epinephrine)
114
Platelet qualitative disorders may be suspected in animals with what 2 conditions?
- Clinical signs of thrombocytopenia (mucosal bleeding, petechiation, ecchymosis)
- Normal platelet count
115
Are platelet qualitative disorders acquired, inherited or can be both?
Can be both.
116
What are 4 examples of causes of acquired platelet qualitative disorders?
- Uremia
- Drugs
- Fibrin degradation products (FDPs)
- Paraproteins
117
What are 7 examples of drugs that can cause platelet qualitative disorders?
- Aspirin
- Phenylbutazone
- Acetaminophen
- NSAIDs
- Some anesthetics
- Xanthine derivatives
- Calcium channel blockers
118
What can inhibit platelet function in disease processes?
Fibrin degradation products (FDPs)
119
What causes paraproteins?
| How does this effect the platelets?
- Plasma cell myeloma
| - Increased globulins coat platelet surface and inhibits function.
120
What are 4 examples of inherited causes of platelet qualitative disorders?
- Absence of glycoprotein receptors
- Absence or reduction in platelet granules
- Signal transduction defect
- von Willebrand's disease
121
What are 3 aspects of von Willebrand's disease?
| Which one is the most significant?
- No defects in platelets
- Defects is in the adhesion molecule that binds platelets during initiation of platelet plug
- Decreased platelet adhesion (most significant)
122
What are 2 things that happen with von Willebrand's disease?
- Platelets float away
| - Platelet plug not formed
123
Von Willebrand's disease leads to what?
Decreased platelet adhesion
124
What are the 2 forms of von Willebrand's?
- Quantitative deficiency (Types 1 and 3)
| - Qualitative abnormality (Type 2)
125
Is quantitative deficiency Type 1 von Willebrand's disease mild or severe?
Type 3?
- Type 1: mild, dogs usually subclinical
| - Type 3 : severe
126
Which factor is vWF a carrier for?
Factor VIII
127
What is the major clinical feature seen with von Willebrand's disease?
What is this exacerbated by?
Does this increase or decrease with age? Successive pregnancies?
- Mild to severe bleeding
- Surgery or trauma
- Decrease, decrease
128
Diagnosis of von Willebrand's is based on what 4 factors?
- Based on signalment
- History
- Medications
- Other primary disorders
129
How does the platelet count appear with von Willebrand's disease?
Normal platelet count
130
What is seen with the buccal mucosal bleeding time with von Willebrand's disease?
Prolonged BMBT
131
If vWD is suspected, analyze the plasma for what?
vWF
132
What effect does vWD have on PTT/ACT?
| What is an exception?
- Both usually normal
| - Both can be prolonged if Factor VIII deficiency is pronounced
133
What is B1-tubulin gene mutation?
| What breed is it seen in?
- Point mutation that alters the cytoskeleton
| - Cavalier King Charles Spaniels
134
What 2 things does the B1-tubulin gene mutation cause?
- Decreased platelet count
| - Increased platelet MCV (macrothrombocytes)
135
T/F: B1-tubulin gene mutation is usually asymptomatic.
True
136
What are 4 examples of lab diagnostics for platelets and what do they measure?
- Blood smears: estimate of platelet numbers, morphology (size)
- Analyzers: platelet counts and MPV
- Bleeding tests: platelet function
- Bone marrow aspirates: platelet production
137
What are 4 major categories of thrombocytopenia causes?
- Loss, consumption
- Destruction
- Production
- Sequestration
138
What do the offspring ingest with alloimmune thrombocytopenia?
Antibody in the colostrum.
139
Piglets with alloimmune thrombocytopenia have a high mortality rate from what?
Hemorrhage
140
What type of vaccination may induce an immune response against the platelets, leading to platelet aggregation and clearance?
Modified-live virus vaccination
141
Thrombocytopenia due to vaccination usually occurs when?
3-10 days post-vaccination
142
Is thrombocytopenia seen with vaccines usually mild or severe?
Mild
143
A complete blood count (CBC) can detect what type of thrombocytopenia?
Severe thrombocytopenia
144
Bone marrow aspirates are used to detect what?
Increased megakaryocytes (immature & mature)
145
What are 3 possible causes of decreased production of platelets?
- Bone marrow hypoplasia
- Neoplasia
- Myelonecrosis or myelofibrosis
146
The degree of thrombocytopenia seen with decreased production depends on what?
Extent of bone marrow disease.
147
What is the most common form of abnormal distribution of platelets?
Sequestration of platelets in large vascular beds.
148
What level of thrombocytopenia is seen with abnormal distribution of platelets?
Mild to moderate thrombocytopenia
149
What are 2 possible reason an analyzer might not measure platelets, leading to pseudothrombocytopenia?
- Too big (macrothrombocytes)
| - Clumped
150
An increased concentration of platelets is known as what?
Thrombocytosis
151
What are 2 major mechanisms of thrombocytosis?
- Increased production
| - Increased distribution in plasma
152
What type of symptoms are usually seen in animals with an increased platelet count?
Animals are usually asymptomatic.
153
What are 2 possible reasons for increased concentration of platelets?
Which one is more common?
- Primary neoplastic production of platelets
| - Secondary or reactive thrombocytosis (more common)
154
What are 5 possible causes of secondary or reactive thrombocytosis?
Which is the most common?
- Chronic inflammatory disease (most common)
- Iron deficiency anemia
- Chronic hemorrhage
- IMHA
- Some neoplasms
155
Increased concentration of platelets can be associated with what 4 situations?
- Rebound from thrombocytopenia
- Post-splenectomy
- Response to some drugs (vincristine)
- Excitement and exercise (epinephrine)
156
Platelet qualitative disorders may be suspected in animals with what 2 conditions?
- Clinical signs of thrombocytopenia (mucosal bleeding, petechiation, ecchymosis)
- Normal platelet count
157
Are platelet qualitative disorders acquired, inherited or can be both?
Can be both.
158
What are 4 examples of causes of acquired platelet qualitative disorders?
- Uremia
- Drugs
- Fibrin degradation products (FDPs)
- Paraproteins
159
What are 7 examples of drugs that can cause platelet qualitative disorders?
- Aspirin
- Phenylbutazone
- Acetaminophen
- NSAIDs
- Some anesthetics
- Xanthine derivatives
- Calcium channel blockers
160
What can inhibit platelet function in disease processes?
Fibrin degradation products (FDPs)
161
What causes paraproteins?
| How does this effect the platelets?
- Plasma cell myeloma
| - Increased globulins coat platelet surface and inhibits function.
162
What are 4 examples of inherited causes of platelet qualitative disorders?
- Absence of glycoprotein receptors
- Absence or reduction in platelet granules
- Signal transduction defect
- von Willebrand's disease
163
What are 3 aspects of von Willebrand's disease?
| Which one is the most significant?
- No defects in platelets
- Defects is in the adhesion molecule that binds platelets during initiation of platelet plug
- Decreased platelet adhesion (most significant)
164
What are 2 things that happen with von Willebrand's disease?
- Platelets float away
| - Platelet plug not formed
165
Von Willebrand's disease leads to what?
Decreased platelet adhesion
166
What are the 2 forms of von Willebrand's?
- Quantitative deficiency (Types 1 and 3)
| - Qualitative abnormality (Type 2)
167
Is quantitative deficiency Type 1 von Willebrand's disease mild or severe?
Type 3?
- Type 1: mild, dogs usually subclinical
| - Type 3 : severe
168
Which factor is vWF a carrier for?
Factor VIII
169
What is the major clinical feature seen with von Willebrand's disease?
What is this exacerbated by?
Does this increase or decrease with age? Successive pregnancies?
- Mild to severe bleeding
- Surgery or trauma
- Decrease, decrease
170
Diagnosis of von Willebrand's is based on what 4 factors?
- Based on signalment
- History
- Medications
- Other primary disorders
171
How does the platelet count appear with von Willebrand's disease?
Normal platelet count
172
What is seen with the buccal mucosal bleeding time with von Willebrand's disease?
Prolonged BMBT
173
If vWD is suspected, analyze the plasma for what?
vWF
174
What effect does vWD have on PTT/ACT?
| What is an exception?
- Both usually normal
| - Both can be prolonged if Factor VIII deficiency is pronounced
175
What is B1-tubulin gene mutation?
| What breed is it seen in?
- Point mutation that alters the cytoskeleton
| - Cavalier King Charles Spaniels
176
What 2 things does the B1-tubulin gene mutation cause?
- Decreased platelet count
| - Increased platelet MCV (macrothrombocytes)
177
T/F: B1-tubulin gene mutation is usually asymptomatic.
True
178
What are 4 examples of lab diagnostics for platelets and what do they measure?
- Blood smears: estimate of platelet numbers, morphology (size)
- Analyzers: platelet counts and MPV
- Bleeding tests: platelet function
- Bone marrow aspirates: platelet production
179
What are 4 major categories of thrombocytopenia causes?
- Loss, consumption
- Destruction
- Production
- Sequestration
