Lecture 1.1c - Cell injury and cell death 1.pdf

Gangrene, infarction and infarct: ◦Gangrene - necrosis visible to the naked eye ‣ An appearance of necrosis ◦Infarction - necrosis caused by reduction in arterial blood flow ‣ A cause of necrosis ‣ Can result in gangrene ◦Infarction - an area of necroti...

Gangrene, infarction and infarct: ◦Gangrene - necrosis visible to the naked eye ‣ An appearance of necrosis ◦Infarction - necrosis caused by reduction in arterial blood flow ‣ A cause of necrosis ‣ Can result in gangrene ◦Infarction - an area of necrotic tissue which is the result of loss of arterial blood supply ‣ An area ischaemic necrosis Gangrene: ◦Gangrene is not a type of necrosis, it is a clinical term used to describe necrosis that is visible to the naked eye. ◦Dry gangrene = necrosis modified by exposure to air (coagulative necrosis) ‣ If there’s mostly coagulation necrosis (I.e. the typical blackening, desiccating foot which dried up before the bacteria could overgrow), we call it dry gangrene ◦Wet gangrene = necrosis modified by infection with a mixed bacterial culture (liquefactive necrosis) ‣ If there’s mostly Liquefactive necrosis (I.e. the typical foul-smelling, oozing foot infected with several different kinds of bacteria), or if its in a wet body cavity, we call it wet gangrene. ◦Gas gangrene - a type of wet gangrene where the infection is with anaerobic bacteria that produce gas. Differences of features observed in gangrenes: What are the common causes of infarction?: ◦Infarction - necrosis caused by reduction in arterial blood flow  Why are some infarcts white?: ◦Anaemic infarcts ◦‘Solid organs’, occlusion of an end artery ◦Often wedge-shaped ◦Coagulative necrosis Why are some infarcts red?: ◦Haemorrhagic infarct ◦Loose tissue ◦Dual blood supply ◦Numerous anastomoses ◦Prior congestion ◦Raised venous pressure ◦Re-perfusion What does infarcted tissue look like?: ◦Thrombosis and embolism are common causes What is the consequence of infarction?: ◦Depends on: ‣ Alternative blood supply ‣ Speed of ischaemia ‣ Tissue involved ‣ Oxygen content of the blood