Assignment on Cell Injury

MM 10402 Assignment on cell injury 1.(a) Define apoptosis and necrosis. Apoptosis: -

Occurs when a cell dies through activation of internally controlled suicide program To eliminate unwanted cells during embryogenesis & in various physiologic processes Also occurs under pathologic conditions, sometimes accompanied by necrosis

Necrosis: -

The more common type of cell death after exogenous stimuli, occurring after such stresses as ischemia & chemical injury. Manifestations: - Severe cell swelling or cell rupture -Denaturation & coagulation of cytoplasmic proteins -Breakdown of cell organelles.

(b) Tabulate the differences between apoptosis and necrosis.

2. (a) List six types of necrosis. 1. 2. 3. 4. 5.

Coagulative necrosis Liquefactive necrosis Gangrenous necrosis Fat necrosis Fibrinoid necrosis

(b) Briefly discuss about each type of necrosis 1. Coagulative Necrosis:  Coagulative necrosis is the commonest type and is ischemic. It may occur in heart, kidney, or adrenal glands and is firm in texture. In coagulative necrosis, architecture of dead tissue is preserved for some days. It may occur due to denaturation of proteins including enzymes.Ischemia results

in coagulative necrosis, except in brain. An infarct is localized area of coagulative necrosis.

2. Liquefactive Necrosis - Necrosis of big tissue with super added putrefaction, with black, foulsmelling appearance is known as liquefactive necrosis (black or green color is due to breakdown of haemoglobin). In liquefactive necrosis, digestion of dead cells leads to liquid mass (infections & hypoxic death in CNS). Autolysis predominates resulting in liquified mass. Examples include cerebral infarction and abscess. Brain cells secrete increased hydrolases. These make neural tissue soft & liquid. Abscess hyrolases from neutrophils liquefy tissue.

3. Gangrenous Necrosis - It is the clinical term for ischemic necrosis of lower limb involving multiple tissue planes with super added bacterial infections. Necrosis and putrifaction by saprophytes takes place.

4. Caseous Necrosis - It is cheese-like, as in tuberculosis. 5. Fat necrosis - In fat necrosis, there is focal area of fat destruction (pancreatic lipase digest cell membrane & form fatty acid + calcium white deposits).

6. -

Fibrinoid necrosis This is not a true degeneration but a strongly eosinophilic stain like fibrin. Location: interstitial collagen and blood vessels (small artery and arteriole) Nature: one kind of necrosis.