300816 Lecture Notes - Lecture 5: Caseous Necrosis, Coagulative Necrosis, Fat Necrosis
Document Summary
Death of tissues following bioenergetic failure and loss of plasma membrane integrity. Induces inflammation and repair and causes include ischaemia, metabolic and/or trauma to cells. Coagulative necrosis is the most common form and can occur in most organs. The gross appearance depends on the cause of death and on vascular alterations. Initially the texture is firm and pale, but may become soft (with ghost outlines under microscopy) as a result of digestion by macrophages. Colliquative necrosis occurs in the brain because of its lack of any supporting stroma; thus the necrotic neural tissue may be liquefied. Caseous necrosis is seen in tuberculosis, with histological examinations showing an amorphous eosinophillic area dotted by nuclear debris. Gangrene is necrosis with breakdown of the tissues (putrefaction) by clostridia. The affected tissues appear black because of the deposition of iron sulphide from degraded haemoglobin. Dry" gangrene is seen in toes, where gradual arterial obstruction in atherosclerosis occurs.
