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MDTA > Platelets > Flashcards

Platelets Flashcards

0
Q

Function of platelets

A

They form the primary haemostatic plug
They provide a phospholipid surface on which clotting factors an work
They cross link the fibrin clot to make it stable

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1
Q

Where are platelets derived from?

A

HSCs

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2
Q

What I the sunendithelial matrix made of ?

A

Collegen
VWF
Tissue factors

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3
Q

What activates coagulation

A

A breach in the endothelium - expose subendithelial matrix. VWF unfolds.

Always little bit happening- more in trauma

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4
Q

What does VWF do?

A

Grab platelets

VWF has receptors for platelets & vice versa

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5
Q

What happens when platelets bind VWF?

A 
Ps become activated
Change shape
Bind to more things
Release contents (granules)
G= dense bodies & a granules
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6
Q

What do granules do?

A

Attract platelets
Attract more platelets
Attract VWF

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7
Q

What dos fibrin do?

A

It’s a glue!

Glues the platelet plug following activation if coagulation cascade

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8
Q

What activates platelets?

A

Thrombin from CC
ADP released from dense bodies
Collagen in vessel wall
Platelets

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9
Q

Platelet activation causes:

A 
A shape change
Formation of pseudopodia
Granule release
Platelet attraction & aggregation 
Provide phospholipid be on which CC can work
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10
Q

What do platelets bind to to form a table thrombus?

A

VWF
Collagen
Fibrin

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11
Q

How can platelets go wrong?

A

To many/few

Poor quality = abnormal function

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12
Q

Name an squired cause of a qualitative disorders of platelet function

A

Myelodysplasia

Bone marrow failing- cells produced are poor quality & low in number

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13
Q

What drugs can interfere with platelets

A

Aspirin
NSAIDs
Clopidogrel

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14
Q

What type of antagonist is clopidogrel?

A

P2Y12

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15
Q

What enzyme does aspirin inhibit?

A

COX 1

Stops formation of thromboxin A2

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16
Q

Name a congenial platelet disorder where they cannot bind to VWF

A

Bernard Soulier

Autosomal recessive

Rare

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17
Q

What congenital condition causes lack of platelet aggregation this no platelet plug?

A

Glanzmann’s thrombasthenia

18
Q

What disease causes abnormal release of granules?

A

Pool disorders

19
Q

What is mucocutaneous bleeding?

A

Bleeding from mucous membranes

20
Q

What’s the normal platelet count?

A

150-450 ✖️ 10 power 9/ L

21
Q

What is thrombocytopenia?

A

Not enough platelets!! ❤️⬇️

< 150

22
Q

What is thrombocytosis?

A

Too many platelets! ❤️❤️❤️⬆️

> 500

23
Q

Causes of ⬆️ platelets (thrombocytosis)

A

Smoking
Splenectomy
Cancer
Iron deficiency

24
Q

What is the physiological cause of thrombocytosis?

A

Cytokine storm…..

Increase megakaryocytes

25
Q

What gene is mutated in Wiskott-Aldrich syndrome?

A

WAS gene

Causes defective actin polymerisation
X-linked recessive

26
Q

Symptoms of W-A syndrome?

A

Thrombocytopenia

Eczema

27
Q

What cells are found in bone marrow?

A

Lots of fat cells
Megakaryocytes
Myeloid precursor cells

28
Q

What condition causes bone marrow to become packed with plasma cells?

A

Myeloma

Can’t produce RBCs/WBCs/platelets

29
Q

What suppresses bone marrow?

A

Chemotherapy

30
Q

Leukopenia

A

⬇️ WBCs

31
Q

What conditions cause ⬇️ platelets?

A 
Glandular fever
Hypersplenism
Liver cirrhosis 
Massive Haemorrhage
Sepsis
Immune
32
Q

What is the blood picture with increased consumption?

A

Low platelets
Normal or high WBCs
Low or normal RBCs

33
Q

Name some secondary causes of autoimmune thrombocytopenia

A 
Autoimmune conditions (SLE, RA)
Drugs (penicillin, quinine, abciximab, heparin)
Viral infections (HIV, hep C & B)
34
Q

Name the primary cause of autoimmune thrombocytopenia

A

I idiopathic immune thrombocytopenia

35
Q

What is the only thing in the blood picture that is affected in ITP?

A

Platelets (reduced)

36
Q

What is ITP

A

Primary autoimmune thrombocytopenia

37
Q

What is the peak age incidence for acute & chronic ITP?

A

A = 2-8

C = older

38
Q

What causes purpuric rash?

A

Leaky endothelia

39
Q

Treatment for ITP

A

1) Corticosteroids, Ig, platelets
2) splenectomy, immunosuppression, anti-CD20 antibody
3) thrombopoietin agonist/ mimetics

40
Q

What produces thrombopoietin?

A

The liver

41
Q

Why does TPO bind to?

A

Megakaryocytes & platelets

42
Q

Normal Hb for women

A

11.5-15.5

43
Q

If platelet count goes below 10 what is probable cause?

A

Immune mediated

MDTA (20 decks)

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