Necrosis (in Greek Νεκρός = Dead) is the name given to unprogrammed death of cells/living tissue (compare with apoptosis - programmed cell death). There are many causes of necrosis including injury, infection, cancer, infarction, inflammation and so on. Death is either the cessation of life in a living organism or the state of the organism after that event. ... Biological tissue is a group of cells that perform a similar function. ... In biology, apoptosis (from the Greek words apo = from and ptosis = falling, pronounced ap-a-tow-sis[1]) is one of the main types of programmed cell death (PCD). ... Programmed cell death (PCD) is the deliberate suicide of an unwanted cell in a multicellular organism. ... Injury is damage or harm caused to the structure or function of the body caused by an outside agent or force, which may be physical or chemical. ... An infection is the detrimental colonization of a host organism by a foreign species. ... When normal cells are damaged or old they undergo apoptosis; cancer cells, however, avoid apoptosis. ... In medicine, infarction is necrosis of tissue due to upstream obstruction of its arterial blood supply. ... Inflammation is the first response of the immune system to infection or irritation and may be referred to as the innate cascade. ...

There are four distinctive morphologic patterns of necrosis:

• Coagulative necrosis - typically seen in hypoxic environments. Cell outlines remain after cell death and can be observed by light microscopy (e.g. myocardial infarction, infarct of the spleen)
• Liquefactive necrosis - is associated with cellular destruction and pus formation (e.g. pneumonia)
• Caseous necrosis - is a mix of coagulative necrosis and liquefactive necrosis (e.g. tuberculosis)
• Fatty necrosis - results from the action of lipases on fatty tissues (e.g. acute pancreatitis)
• Fibrinoid necrosis - caused by immune-mediated vascular damage. It is marked by deposition of fibrin-like proteinaceous material in arterial walls, which appears smudgy and acidophilic on light microscopy.

A myocardial infarction occurs when an atherosclerotic plaque slowly builds up in the inner lining of a coronary artery and then suddenly ruptures, totally occluding the artery and preventing blood flow downstream. ... Pneumonia (the ancient Greek word for lungs) is defined as an inflamation, usually caused by infection, involving the alveoli of the lungs. ... Tuberculous lungs show up on an X-ray image Tuberculosis is an infection with the bacterium Mycobacterium tuberculosis, which most commonly affects the lungs (pulmonary TB) but can also affect the central nervous system (meningitis), lymphatic system, circulatory system (miliary TB), genitourinary system, bones and joints. ... A lipase is an enzyme whose principal substrate is a lipid. ... The blood vessels are part of the circulatory system and function to transport blood throughout the body. ... Fibrin is a protein involved in the clotting of blood. ... Microscopy is any technique for producing visible images of structures or details too small to otherwise be seen by the human eye. ...

See also

• Peripheral vascular disease
• Aseptic bone necrosis
• Gangrene