Ischaemia and Infarction

Question 1

What is the most important effect of ischaemia on cells?

Answer 1

The reduction in ATP leading to more anaerobic glycolysis, decreased membrane pump activity and decrease in protein synnthesis.

Usually can not undergo apoptosis

Question 2

Howcan ischaemia affect tissues at different levels?

Answer 2

Can range from no damage
functional defects in some of the parenchyma eg myocardial dysrythmias
adaptation to fatty change or atrophy
apoptosis
infarction

Question 3

What are some other factors that influence tissue outcome due to an occluded vessel

Answer 3

Layout of the blood supply (collateral)
Size of occluded vessel
Speed of onset
duration
metabolic demand
adequacy of circulatory system
reperfusion (after being ischamic, sudddenly supplied with O2)

Question 4

What are the two different appearances of infarcted tissue?

Answer 4

Red/haemorraghic: tissues with dual blood supply; or in tissues when blood flow can be restablished after previous occlusion

White: infarcts in solid tissue supplied by a single artery, often wedge shaped

Coagulative necrosis is the normal pattern. Diff. in brain

Question 5

How atherosclerotic plaque in coronary arteries can be bad

Answer 5

Angina pectoris- transient ischaemia, no necrosis
Chronic IHD with heart failure
MI: complete blockage showing transmural or subendocardial patterns

Question 6

What are some treatments of MI?

Answer 6

NB must be done fast
thrombolitic agents
mechanical re expansion of occluded vessel (angioplasty + stenting)
Coronary artery bypass grafting

Question 7

What is reperfusion injury?

Answer 7

Idea of reperfusion followimg long periods of ischaemia, so the cells biology has changed.

When oxygen is reintroduced, it it turned into ROS that are free radicals and further damage the cell (oxidative stress) by : lipid peroxidation. damaging enzymes (double bonds in aa) and damaging DNA (thymine)