Bleeding Disorders Flashcards

1
Q

What is haemostasis?

A

The cessation of bleeding following trauma to blood vessels.

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2
Q

What is FIII?

A

Tissue factor

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3
Q

What is FII?

A

Prothrombin

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4
Q

What are the principle haemostatic mechanisms?

A

Platelet aggregation, fibrin polymerisation and vasoconstriction

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5
Q

What are platelets?

A

Small anucleate fragments

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6
Q

What are platelets derived from?

A

Megakayocytes

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7
Q

What do platelets respond to?

A

A variety of chemical stimuli

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8
Q

What do platelets circulate as?

A

Resting disks

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9
Q

What is VWF?

A

An adhesion molecule present in plasma and subendothelial matrix

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10
Q

What is fibrinogen?

A

An adhesion molecule present in the plasma

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11
Q

What does coagulation mean?

A

The solidification of liquid plasma

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12
Q

What is FIIa?

A

Thrombin

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13
Q

What is FI?

A

Fibrinogen

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14
Q

What is the coagulation cascade initiated by?

A

The exposure of blood (plasma) to a trigger which sets off a series of enzymes reactions

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15
Q

What is the final step in the coagulation cascade?

A

Polymerisation of fibrin monomers to format a gel like mesh

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16
Q

Why is there no factor IV?

A

Factor VI was discovered as calcium ions but by this time factor V had already been named

17
Q

What can bleeding disorders be a result of?

A

Primary or secondary haemostasis

18
Q

What is primary haemostasis?

A

Formation of a platelet plug

19
Q

What is secondary haemostasis?

A

Consolidation of the thrombus by fibrin strands

20
Q

What are the disorders of primary haemostasis?

A

Platelet disorders (thrombocytopenia, platelet dysfunction), von willebrands disease, connective tissue disorder

21
Q

What are the disorders of secondary haemostasis?

A

Clotting factor deficiencies (haemophilias, liver disease), anti coagulant overdose, overactive fibrinolysis

22
Q

What are the patterns of bleeding from primary haemostatic disorders?

A

Bleeding from skin wounds, bleeding from mucous membranes, GI bleeds, surgical bleeding, cranial haemorrhages (rare)

23
Q

What are the patterns of bleeding from secondary haemostatic disorders?

A

Haemoarthrosis (joints), intramuscular bleeding, cranial haemorrhages (rare)

24
Q

What can be noted in thrombocytopenia?

A

Low platelet count, impaired bone marrow function, autoimmunological destruction

25
Q

What can be noted in Von Willebrand’s disease?

A

Qualitative or quantitative deficiency in Von Willebrand’s factor, reduced circulating factor VIII

26
Q

What can be noted in Glanzmann’s thrombocytopenia/bernard-soulier syndrome?

A

Autosomal inheritance with varying severity, caused by defects in VWF gene.

27
Q

What is thrombocytopenia?

A

Most common cause of defective primary haemostasis

28
Q

Platelet + autoantibodies ➡ sensitised platelet = ?

A

Destroyed by macrophage

29
Q

Haemophilia A is caused by?

A

FVIII deficiency

30
Q

Haemophilia B is caused by?

A

FIX deficiency

31
Q

What is haemophilia C caused by?

A

FXI deficiency, liver disease, vitamin k deficiency, warfarin overdose