Ischaemia and Infarction

Question 1

Ischaemia vs Infarction

Answer 1

1. Ischaemia
   - Reduced blood supply causing hypoxia/lack of O2, nutrients, and removal of waste
   - No Necrosis
2. Infarction
   - Reduced blood supply due to occlusion=> Cell necrosis

Question 2

Susceptibility of a tissue to ischaemia/infarction?

Answer 2

1. Watershed area
2. Areas with or without collateral circulation
3. O2 content of blood
4. Rate of development of the occlusion

Question 3

Causes of ischaemia/infarction?

Answer 3

1. Shock
2. Obstruction
   - Atherosclerosis
   - Thrombosis
   - Embolism

Question 4

Common illnesses due to infarction?

Answer 4

1. MI
2. Cerebrovascular infarct
3. Bowel infarct
4. Pulmonary infarct
5. Ischaemic necrosis of the extremities

Question 5

Macroscopic appearance of infarcts?

Answer 5

1. Wedge shaped
2. Initially poorly defined with a narrow rim of hyperaemia
3. Later sharply defined, pale (if solid), red (if spongy)

Question 6

Microscopical appearance of infarcts?

Answer 6

1. Haemorrhage initially
2. Cell necrosis
3. Acute inflamm
4. Chronic inflamm
5. Granulation tissue
6. Scar

Question 7

What is re perfusion injury?

Answer 7

Cell injury due to restoring blood flow after ischaemia

• Free radical formation
• Failure of Ca2+/ATPase
• Ca2+ Excess=> cell death

Question 8

Types of necrosis seen in:

1. MI
2. Stroke
3. Diabetes
4. Trauma to fat
5. TB

Answer 8

1. Coagulative necrosis
2. Liquefactive necrosis
3. Gangrenous (subtype of coagulative necrosis)
4. Fat necrosis
5. Caseous necrosis

Question 9

What is arteriosclerosis?

Answer 9

Narrowing of arterioles (intimal hyperplasia) due to hypertension.

Common in diabetics (hyaline arteriosclerosis) and in the kidneys.

Question 10

What vessels are less likely to have an atheroma form and why?

Answer 10

Veins are less likely to form an atheroma because they have a much lower pressure than arteries.
Therefore veins are more likely to undergo thrombosis.