Haemostasis, Thrombosis And Embolism (6) Flashcards

0
Q

How do platelets help reduce blood loss?

A
  • Adhere to damaged vessel wall
  • Adhere to each other
  • Forms a platelet plug
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1
Q

What does homeostasis depend on?

A
  • Vessel wall
  • Platelets
  • Coagulation system
  • Fibrinolytic system
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2
Q

What is the platelet release reaction?

A
  • ATP -> ADP
  • ADP thromboxane A2 cause platelet aggregation
  • 5HT platelet factor 3 also released
  • PF3 important in coagulation
  • Platelets coalesce after aggregation
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3
Q

How does coagulation occur?

A
  • Series of inactive components -> active components (cascade)
  • Prothrombin -> thrombin
  • Thrombin stimulates fibrinogen -> fibrin
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4
Q

How is coagulation tightly regulated?

A
  • Balance of pro coagulant and anticoagulant factors
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5
Q

What is Fibrinolysis?

A
  • Breakdown of fibrin

- Plasminogen -> plasmin (catalysed by plasminogen activation)

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6
Q

Give 2 examples of fibrinolytic factors

A
  • Streptokinase

- TPA

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7
Q

Give 4 examples of endothelium anti-thrombotic factors.

A
  • Plasminogen activators
  • Prostacyclin
  • Nitrous oxide (NO)
  • Thrombomodulin
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8
Q

What is a thrombosis?

A
  • Formation of a solid mass of blood within circulation system
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9
Q

Why may a thrombosis form?

A
  • Abnormalities of vessel wall
  • Abnormalities of blood flow
  • Abnormalities of blood components
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10
Q

How may abnormalities of the vessel wall occur?

A
  • Atheroma
  • Direct injury
  • Inflammation
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11
Q

Why may abnormalities of blood flow occur?

A
  • Stagnation

- Turbulence

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12
Q

How may abnormalities of blood components occur?

A
  • Smoking
  • Post-op
  • Post-partum (post-natal)
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13
Q

What is the appearance of an arterial thrombus?

A
  • Pale
  • Granular
  • Lines of Zahn
  • Lower cells content
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14
Q

What is the appearance of a venous thrombi?

A
  • Soft
  • Gelatinous
  • Deep red (higher cell content)
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15
Q

What are the 5 main outcomes of thrombosis?

A
  • Lysis
  • Propagation
  • Organisation
  • Recanalisation
  • Embolism
16
Q

What is lysis?

A
  • Complete dissolution of a thrombus
  • Fibrinolytic system active
  • Bloodflow re-established
  • Most likely when thrombi are small
17
Q

What is propagation?

A
  • Progressive spread of thrombosis
  • Distally in arteries
  • Proximally in veins
18
Q

What is organisation as an outcome of thrombosis?

A
  • Reparative process
  • Ingrowth of fibroblasts and capillaries (like granulation tissue)
  • Lumen remains obstructed
19
Q

What is recanalisation?

A
  • Bloodflow re-established but usually incomplete

- One or more channels formed through organising thrombus

20
Q

What are the arterial effects of thrombosis?

A
  • Ischaemia
  • Infarction
  • Depends of site and collateral circulation
21
Q

What are the venous effects of thrombosis?

A
  • Congestion
  • Oedema
  • Ischaemia
  • Infarction
22
Q

What is an embolism?

A
  • Blockage of a blood vessel by solid, liquid or gas at a site DISTANT from its origin
23
Q

What is the main type of embolism?

A
  • Thrombo-embolism
24
Q

What are the other possible types of embolisms?

A
  • Air
  • Amniotic
  • N2
  • Medical equipment
  • Tumour cells
25
Q

Where can thrombo-emboli originate from?

A
  • Systemic veins pass to the lungs (PE)
  • Heart pass via aorta to renal, mesenteric and other arteries
  • Atheromatous carotid arteries pass to brain
  • Atheromatous abdominal aorta pass to arteries of legs
26
Q

What are the pre-disposing factors of deep vein thrombosis?

A
  • Immobility
  • Post-op
  • Pregnancy and post natal
  • Oral contraceptives
  • Severe burns
  • Cardiac failure
  • Disseminated cancer
27
Q

How can DVT be prevented?

A
  • Heparin sub-cutaneously

- Leg compression during surgery

28
Q

What treatment is there for DVT?

A
  • Intravenous heparin

- Oral warfarin

29
Q

What is a massive PE?

A
  • > 60% reduction in bloodflow

- Rapidly fatal

30
Q

What is a major PE?

A
  • Medium sized vessels blocked

- SOB +/- cough and blood stained sputum

31
Q

What is a minor PE?

A
  • Small peripheral pulmonary arteries blocked

- Asymptomatic or minor SOB

32
Q

What can recurrent minor PEs lead to?

A
  • Pulmonary hypertension