BMS 81100 - Physiology > Platelets > Flashcards

Platelets Flashcards

(57 cards)

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1
Q

Platelet morphology

A
  1. Flat discs
  2. Granules
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2
Q

Alpha granules

A
  1. Adhesive proteins (vWf, fibrinogen, GPIb, GPIIb)
  2. Growth modulators
  3. Coagulation factors
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3
Q

Dense (delta) granules

A
  1. ADP/ATP, Serotonin, Calcium
  2. Receptors
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4
Q

VonWillenbrand Factor or VWF

A
  1. Present in endothelial cells and megakaryocytes
  2. Involved in platelet adhesion and aggregation: alpha granules
  3. Stabilizes FVIII of coagulation
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5
Q

Receptors on the membrane

A
  1. GPIa/IIa (a2B1) and GPIV (bind collagen)
  2. GPIb/IX/V (bind wWf)
  3. PIVVb/IIIa (binds free fibrinogen and wWf)
  4. P2 and PY2Y12 (ADP/ATP receptors)
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6
Q

Secretion of _________________________ inhibits platelet activation and aggregation

A
  1. prostacyclin
  2. nitric oxide
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7
Q

Expression of ___________________ prevents activation of pro-clotting factor

A
  1. thrombomodulin
  2. tissue factor pathway inhibitor
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8
Q

What bridges platelets together?

A

Aggregation: fibrinogen

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9
Q

What prevent platelet from floating around?

A

Adhesion: Collagen and vWF

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10
Q

What lipids are external in an inactivated platelet?

A
  1. Phosphatidylcholine
  2. Sphingomyelin
  3. Sphingolipids
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11
Q

What lipids are external in an activated platelet?

A
  1. Phosphatidylserine (PS)
  2. Phosphatidylethanolamine
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12
Q

Released from dense granules and leads to platelet activation

A
  1. ADP
  2. TXA2 (thrombaxane)
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13
Q

Released from alpha granules, leads to platelet adherence and activation

A

vWF

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14
Q

Released from alpha granules, assists in long-term wound healing

A

Platelet derived growth factor

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15
Q

Steps leading to platelet plug formation

A
  1. Vessel damage causes vWF to be secreted
  2. vWF binds platelets to collagen in vessel wall
  3. Platelets are activated and express fibrinogen receptors (GPIIb/IIIa)
  4. Fibrinogen binds fibrinogen receptors
  5. Platelet aggregation
  6. ADP and TXA2 release alpha and dense granules
  7. Alpha granules contains vWF and PGDF
  8. Dense granules contains ADP and TXA2
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16
Q

Primary, Secondary, Tertiary Hemostasis

A

Primary: plug formation
Secondary: Fibrin formation
Tertiary: fibrinolysis

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17
Q

Precursor to platelet

A

Megakaryocyte

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18
Q

Regulators of thrombopoiesis

A
  1. IL-3
  2. IL-6
  3. IL-11
  4. TPO
  5. EPO
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19
Q

Thrombocytopenia

A

decreased platelet count

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20
Q

Thrombopathy

A

function defect with platelet

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21
Q

Why is nitric oxide important?

A

It has a negative charge to repel platelets

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22
Q

Important aspects of vessel

A
  1. Endothelial cells (produces NO, PGI2, vWF)
  2. Subendothelium (collagen, fibrous tissue)
  3. Smooth muscle
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23
Q

Functions of platelets

Study These Flashcards
A
  1. Maintain vascular integrity
  2. Responsible for primary hemostasis
  3. Provide an environment favorable to secondary hemostasis
  4. Promote vascular healing
  5. Role in inflammation
24
Q

Podosome

Study These Flashcards
A

stubby arm of megakaryocyte

25
Proplatelet
long arm of megakaryocyte that divides into platelets
26
How long does it take to make platelets?
5-8 days
27
Hemostasis
the arrest of bleeding either by physiologic (primary and secondary hemostasis) or surgical means
28
Coagulation
the sequential process that results in the formation of an insoluble fibrin clot (secondary hemostasis)
29
Hematoma
bleeding outside of blood vessels
30
Two arms of secondary hemostasis
1. Intrinsic Pathway 2. Extrinsic Pathway *both meet in the middle for the Common Pathway to form fibrin
31
Coagulation factors in Intrinsic Pathway
1. XII - Hageman factor 2. XI 3. IX 4. VIII
32
Coagulation factors in extrinsic pathway
1. III - Tissue Factor 2. VII
33
Coagulation factors of common pathway
1. X 2. V 3. II - Prothrombin 4. I - Fibrinogen
34
Factor XIII
Technically outside common pathway. It is a fibrin stabilizing factor (crosslinks fibrin to make it more stable)
35
Factor IV
Calcium, present in all pathways
36
PTT vs PT
PTT: tests intrinsic pathway function PT: tests extrinsic pathway function
37
Kellikrein
Causes cleavage and activation of facotrs XII, IX, and VII
38
Coagulation factors are produced by __________
liver
39
Coagulation factors are dependent on this vitamin
Vitamin K is a cofactor. Without it, the animal will bleed out.
40
EDTA
chelates calcium irreversibly, without calcium it will prevent coagulation
41
Citrate
chelates calcium but it is reversible, can add calcium later to test coagulation
42
Activated Clotting Time Test
1. requires whole blood in "ACT tube" 2. requires >10,000 platelets 3. tests the time it takes to coagulate (~30 seconds) 4. Prolonged if <5% of normal factor quantity
43
Activated Partial Thromboplastin Time
1. requires noncoagulated plasma in citrate tube (contains kaolin, silicate, phospholipid) 2. Add calcium 3. tests the time it takes to form fibrin clot 4. Prolonged if <30% of normal factor quantity
44
Prothrombin Time Test
1. requires noncoagulated plasma in citrate tube (contains thromboplastin) 2. add calcium 3. test the time it takes to form fibrin clot 4. Prolonged if <30% of normal factor quantity
45
If PTT is normal and PT is prolonged, then where it the problem?
Extrinsic pathway
46
If PT is normal and PTT is prolonged, then where is the problem?
Intrinsic pathway
47
If PTT and PT are both prolonged, then where is the problem?
We likely have a issue with: 1. liver (produces factors) 2. vitamin K (cofactors for factors) 3. DIC - disseminated intravascular consumption (increase of consumption of factors)
48
Hemophilia A
deficiency of factor 8
49
Hemophilia B
deficiency of factor 9
50
Diseases important in hemostasis
1. Hereditary (factor deficiency) 2. Acquired (factor depletion/antagonism)
51
What can cause Vitamin K to decrease?
Rodenticide like warfarin
52
Fibrinolysis
1. Plasminogen binds fibrin in clot formation 2. Plasminogen activated to plasmin 3. Plasmin degrades fibrin 4. FDP and d-dimers are released which inhibit hemostasis
53
What activates plasminogen?
1. F-XIIa (Hageman factor) 2. Urokinase 3. tPA (from activated endothelial cells)
54
Systems of Anticoagulation
1. Antithrombin + Heparin (inhibit thrombin factors) 2. Thrombomodulin + thrombin (reduces thrombin availability) 3. Endothelial secretion (PG-I2, NO, ADPase) 4. TFPI
55
Thrombin
1. upregulates coagulation 2. activates platelets 3. works with prothrombin (FII)
56
TPA
tissue plasminogen activator 1. activates plasminogen to plasmin 2. degrades fibrin
57
Molecules that bind escaped plasmin
1. a2 antiplasmin 2. a2 - macroglobulin
BMS 81100 - Physiology
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