35. Clinical and morphological forms of necrosis: macro-, microscopic characteristics, examples of diseases.

Clinical and morphological forms of necrosis. These forms are distinguished depending on the features of morphological and clinical manifestations of a particular form of necrosis, taking into account the etiology, pathogenesis and structural and functional features of the organ in which necrosis develops.

The following forms of necrosis are distinguished:

•coagulation.

•colliquative.

• gangrene.

• Sequestration.

• heart attack

36. Gangrene: definition, causes, types, macro-microscopic signs, outcomes, clinical significance.

Gangrene (from the Greek gangrania — fire) is the necrosis of tissues in contact with the external environment. The tissues have a black color as a result of the formation of iron sulfide from hemoglobin iron and hydrogen sulfide in the air. Gangrene can develop in various parts of the body, lungs, intestines, uterus. There are varieties of gangrene — dry, wet, gas and pressure sores.

With dry gangrene, tissues are mummified, and the zone of demarcation inflammation is clearly defined at the border with preserved living tissue. It occurs in the extremities and on the body with atherosclerosis, frostbite and burns, Raynaud's disease and vibration disease, with severe infections.

Pathomorphology: Tissues acquire a brownish-gray, gray-green or black color, like burnt tissues, (due to the breakdown of hemoglobin in the form of sulfmethemoglobin, blood pigments and their transformation into iron sulfide). Gangrenous tissue areas have no defined boundaries.

Wet gangrene occurs in tissues under the action of putrefactive microorganisms. The tissue swells, becomes edematous, emits a fetid odor, the demarcation zone is not defined. Wet gangrene occurs in the lungs, intestines and uterus. In children weakened by measles, wet gangrene can develop on the skin of the cheeks, perineum and is called a noma (Greek. sweat is a water cancer).

Bedsore is a type of gangrene of trophoneurotic origin. It occurs in places of greatest pressure in weakened patients suffering from cardiovascular, infectious, oncological and nervous diseases. Bedsores are usually localized in areas of the body that are exposed to the greatest pressure in bedridden patients.

Gas (anaerobic) gangrene occurs in injuries and other wounds with massive destruction of muscles and even bone crushing under the influence of certain anaerobic microorgs (Vas. perfrmgens, etc.), an image in the process of vital gases. At the same time, the swollen dead tissue does not have clearly defined boundaries. Due to the spread of blood circulation and the breakdown of erythrocytes in the dead tissue, a large number of sulfmethemoglobin, blood pigments and iron sulfide are formed, the dead mass is dark brown/ almost black.

Causes of gangrene:

1. trauma (burn, frostbite)

2. infections

c) vascular disorders (atherosclerosis, arterial thrombosis, venous congestion, lymphostasis).

The significance and outcome of gangrene depend on the cause, the specific strata and functions of the cl-k and tc-y, the reactive composition of the organ and the influence of the environment. environment, but always an irreversible pathological process.Under the influence of necrosis, decay products of dead cells and tissues, a reactive, so-called demarcation inflammation occurs with vascular hyperemia, the release of serous exudate, leukocytes, lymphocytes and macrophages from them.