pathology of ischaemia and infarction

Question 1

what are the two types of hypoxia?

Answer 1

hypoxic - low inspired 02 or normal inspired but low PaO2

anaemic - normal inspired 02 but abnormal blood

stagnant - abnormal delivery (could be local such as occlusion of a vessel or systemic during shock)

cytotoxic - abnormal at tissue level

Question 2

list two factors affecting oxygen demand

Answer 2

Tissue itself - different tissues have different requirements

Activity of tissue above baseline value

Question 3

what do infarcts appear as in less than 24 hours?

Answer 3

A few hours to 12 hours post insult, see swollen mitochondria on Electron Microscopy

no change on visual inspection

Question 4

what do infarcts appear as between 24- 48 hours?

Answer 4

Pale infarct: e.g. myocardium, spleen, kidney Solid tissues
Red infarct: e.g. in lung, liver Loose tissues, previously congested tissue; second/continuing blood supply, venous occlusion

Microscopically: acute inflammation initially at edge of infarct; loss of specialised cell features

Question 5

what do infarcts appear as 72 hours onwards?

Answer 5

Pale infarct - yellow/white and red periphery
Red infarct - little change
Microscopically: chronic inflammation; macrophages remove debris; granulation tissue; fibrosis