Thrombosis and Infarction Flashcards

1
Q

Define clot

A

Solid mass of blood constituents formed after death

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2
Q

Define thrombus

A

Solid mass of blood constituents formed in life

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3
Q

3 predisposing factors (Virchows triad)

A

Changes in flow, change to vessel wall, changes in blood constituents

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4
Q

Define embolism

A

Process of a solid mass in the blood being carried through the circulation until it causes an occlusion

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5
Q

6 causes of embolus

A

Fat, air, thrombus, bacteria, amniotic fluid, tumour

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6
Q

2 reasons clots are rare

A

Laminar flow (cells travel in centre of vessels and don’t touch the sides). Endothelial cells that line vessels are not ‘sticky’ when healthy

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7
Q

2 stages of thrombosis

A

Platelet aggregation and clotting cascade

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8
Q

Define ischaemia

A

Reduction in blood flow to a tissue without any implications

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9
Q

Define infarction

A

Reduction in blood flow to a tissue to the point that it can not support the demands of the cells so they die

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10
Q

3 organs with dual blood supply

A

Liver - portal venous and hepatic artery. Lung - pulmonary veins and bronchial arteries. Brains - Circle of Willis

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11
Q

Describe the course of arterial thrombosis

A

Atheromatous plaque consisting of a slightly raised fatty streak, protrudes into lumen causing turbulence, this causes loss of intimal cells. Turbulence predisposes to fibrin deposition and platelet clumping. Collagen is exposed & platelets settle

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12
Q

How are lines of Zahn formed?

A

Alternating layers of platelets and a fibrin meshwork in which RBC get trapped

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13
Q

What initiates venous thrombosis?

A

Most begin at valves where there is natural turbulence, may be damaged by trauma, stasis or occlusion

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14
Q

When is venous thrombosis most likely?

A

Post surgery, when blood pressure is allowed to fall, following a MI, immobilisation,

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15
Q

What is thrombophlebitis?

A

When a thrombosed vein becomes inflamed

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16
Q

What is phlebothrombosis?

A

When an inflamed vein becomes thrombosed

17
Q

Clinical signs of arterial thrombosis

A

Area of impaired supply becomes cold, pale and painful. Eventually the tissue dies and gangrene occurs

18
Q

Clinical signs of venous thrombosis

A

Tender, swollen and red

19
Q

Describe the structure of an atherosclerotic plaque

A

central lipid core, cap of fibrous tissue containing macrophages, mast cells and T lymphocytes

20
Q

What is a thrombotic cerebral infarction?

A

Arterial thrombus due to atheroma in any of the vessels supplying the brain

21
Q

What is a hypertensive stroke?

A

High blood pressure leads to atheroma and disruption of the autoregulation of cerebral circulation

22
Q

5 risk factors for atheroma

A

Male, increased blood pressure, increased age, smoking, diabetes

23
Q

What is a fatty streak?

A

Yellow elevation of intimal lining made up of lipid laden macrophages

24
Q

3 stages of formation of atheroma

A

Fatty streak formation - lipids deposited, inflammation, increased permeability and white blood cell recruitment.
Fibrolipid plaque formation, lipid stimulates formation of fibrocollagenous tissue - thinning of muscular media.
Complicated atheroma - prone to rupture, may be calcified, rupture activates clot/thrombosis -> MI/angina