platelets

Question 1

Anucleate cells derived from megakaryocytes

in the bone marrow

Answer 1

platelets

Question 2

platelets:

1. production
2. nl count
3. circulation lifespan

Answer 2

1. production: GM-CSF, IL-3, IL-6, TPO
2. nl count: 150,000- 400,000
3. circulate in the inactive state for 7-10 days

Question 3

Alpha granules:

1. fibrinogen
2. thrombospondin
3. vWF
4. Factor V
5. Platelet factor 4
6. Beta thromboglobulin
7. PDGF (platlet derived growth factor)
8. P-selectin

Answer 3

1. fibrinogen- aggregation
2. thrombospondin- aggregation
3. vWF- adhesion/aggregation
4. Factor V- fibrin clot
5. Platelet factor 4- heparin antagonist–promotes fibrin clot
6. Beta thromboglobulin- recruits fibroblasts
7. PDGF (platlet derived growth factor)- recruits fibroblasts
8. P-selectin- adhesion of activated platelets to phagocytes

Question 4

dense granules

1. ADP and ATP
2. Serotonin (5-HT)
3. calcium

Answer 4

1. ADP and ATP- platelet activation and recruitment
2. Serotonin (5-HT)- vasoconstriction
3. calcium- cofactors for factors forming fibrin clot

Question 5

lysosomes

Answer 5

are granules that contain hydrolytic enzymes which phagocytose debris

Question 6

Glycoprotein (GP) Ib (Ib/IX/V):

Answer 6

vWF receptor

Question 7

Glycoprotein Ia/IIa:

Answer 7

collagen receptor

Question 8

Glycoprotein IIb/IIIa:

Answer 8

fibrinogen receptor

Question 9

procoagulant activity (2)

Answer 9

1. thrombin receptor

2. phospholipids

Question 10

P-selectin (activated platelets only)

Answer 10

leucocyte adhesion

Question 11

bound to the collagen in the subendothelium of the damaged vessel wall, binds to platelets via GPIb complex, acting as a bridge

Answer 11

vWF

Question 12

in the damaged vessel wall can bind to the platelet via GPIa/IIa

Answer 12

collagen

Question 13

involved in adhesion for platelets (2)

Answer 13

1. vWF

2. collagen

Question 14

activating agents in platelets (6)

Answer 14

1. thromboxane A2
2. thrombin
3. epinephrine
4. ADP
5. collagen
6. arachidoinic acid

Question 15

three actions of the activating agents

Answer 15

1. enhances cell interaction (GPIIb/IIIa)
2. induces platelet shape change and secretion
3. phspholipids on plasma membrane activate clotting on the external surface

Question 16

shape change with platelets

Answer 16

change from discoid to spherical- develop long pseudopods

Question 17

where do the granules release their contents?

Answer 17

into the canalicular system

Question 18

in aggregation the platelet-platelet interaction mediated by ______ and promoted by thombospondin

Answer 18

GPIIb/IIIa with fibrinogen

Question 19

what does ADP and thromboxane A2 do in aggregation?

Answer 19

swelling, membrane adhere and further release reaction

Question 20

exposure of membrane ___ for coagulation

Answer 20

PL

Question 21

_____ stimulates vascular smooth muscle cells, hasten healing

Answer 21

PDGF

Question 22

Clot retraction:

tenase complex

Answer 22

FIXa, VIIIa and X = FXa

Question 23

clot retraction:

prothrombinase complex

Answer 23

FXa, Va, and II = thrombin

Question 24

laboratory studies:

1. quantitative
2. qualitive

Answer 24

1. quantitative: platelet count and morphology

2. qualitative: aggregation and PFA100

Question 25

Anticoagulated whole blood under high sheer rate passes through an aperature with two membranes coated with either collagen/epinephrine or collagen/ADP

Answer 25

PFA-100

Question 26

PFA-100 affected by

Answer 26

thrombocytopenia and to some degree anemia

Question 27

PF-100: 1. collagen/epi: 2. collagen/ ADP:

Answer 27

1. collagen/epi: nl<180 sec | 2. collagen/ ADP: nl<116 sec

Question 28

thrombocytopathies

Answer 28

abnormal platelet function

Question 29

thrombocytopenia

Answer 29

platelet count<150,000

Question 30

1. GPIb (vWF receptor) 2. abnormal adhesion/agglutination 3. prolonged bleeding time thrombocytopenia with large platelets

Answer 30

Bernard Soulier disease

Question 31

1. GPIIb/IIIa (fibrinogen receptor) 2. abnormal aggregation and PFA-100 3. prolonged bleeding time

Answer 31

Glanzmann’s thrombasthenia

Question 32

acquired thrombocytopathy (3)

Answer 32

1. drugs- ASA, NSAID 2. renal insufficiency- uremia 3. myeloproliferative disorders/ myelodysplastic syndromes

Question 33

ASA (aspirin) irreversibly, NSAID’s reversibly acetylate and thus inhibit ______, resulting in reduced ________ synthesis and granule release

Answer 33

ASA (aspirin) irreversibly, NSAID’s reversibly acetylate and thus inhibit cyclo-oxygenase, resulting in reduced thromboxane A2 synthesis and granule release

Question 34

powerful vasoconstrictor and potentiates aggregation

Answer 34

Thromboxane A2

Question 35

autosomal dominant, large platelets, dohle bodies in the wbc’s

Answer 35

May-Hegglin anomaly -

Question 36

X-linked recessive, eczema, immune dysfunction

Answer 36

Wiskott-Aldrich syndrome –

Question 37

autosomal recessive, abnormal hand/wrist, cardiac lesions

Answer 37

Thrombocytopenia with absent radii (TAR) –

Question 38

autosomal dominant, interstitial nephritis, deafness, large platelets

Answer 38

Epstein’s/Alport syndrome –

Question 39

stem cell disorder, can also be acquired

Answer 39

Megakaryocytic hypoplasia/aplastic anemia –

Question 40

acquired thrombocytopenia due to decreased production (4)

Answer 40

1. infiltrative process- malignancy 2. infectious- viral 3. drugs- chemotherapy 4. toxins- radiation

Question 41

acquired thrombocytopenia due to increased destruction (7)

Answer 41

1. drugs- heeparin/HIT 2. immune thrimbocytopenic purpura/ ITP 3. thrombotic thrombocytopenic purpura (TTP)/ hemolytic uremic syd=ndrime (HUS) 4. disseminated intravascular coagulation/DIC 5. APLA 6. HELLP syndrome/pre-eclmapsia 7. hyperspenism

Question 42

auto-immune disorder, antibody:antigen complex on the surface of the platelet which targets it for removal by the RES

Answer 42

Immune thrombocytopenic purpura (ITP):

Question 43

1.Adults 2.Fever, thrombocytopenia microangiopathic anemia, acute renal failure, neurologic dysfunction 3. ADAMTS13-destruction or deficiency which leads to ultra large vWF multimers and aggregation of platelets and thrombosis 4. Normal PT/PTT 5. Rx: plasma exchange

Answer 43

Thrombotic thrombocytopenic purpura

Question 44

1. Children 2. Diarrhea infection often E. coli strain 3. Microangiopathic anemia, thrombocytopenia severe renal failure 3. ADAMTS13 – normal 4. Normal PT/PTT 5. Rx: supportive care

Answer 44

Hemolytic Uremic Syndrome

Question 45

Disseminated intravascular coagulation: 1. Consumptive coagulopathy associated with 2. Initiated by 3. Clinical – 4. Lab –

Answer 45

1. Consumptive coagulopathy associated with thrombocytopenia, excessive fibrinolysis and reduced coagulation factors 2. Initiated by endotoxin, infections (meningococcemia, etc), tissue factor release, tissue injury, proteases, toxins, malignancy, obstetrical complications 3. Clinical – bleeding and thrombosis 4. Lab – microangiopathic HA, thrombocytopenia, prolonged PT/PTT, TT, decreased fibrinogen, increased d-dimer

Question 46

does the extrinsic pathway depend of platelets?

Answer 46

Nope, the extrinsic pathway is only made up of FVII

Question 47

gray platelet syndrome

Answer 47

there is a decreased or absent number of alpha granules.

Question 48

Chediak-Higashi syndrome is a

Answer 48

white blood cell disorder due to a failure of phagolysosome formation.