Apoptosis and necrosis

Apoptosis

Apoptosis is translated from Greek as "falling away". The process of apoptosis is a physiological cell death in vivo. It is known that the basis for the growth of tissues and sexual reproduction is cell division. In the body constantly is their destruction, necrosis, and substitution. Cessation of the functions of individual cells is a necessary condition for the normal vital process. Destruction and cell death is always observed in the period of embryonic development during the laying of organs and tissue differentiation.

Therefore, apoptosis is a natural, genetically determined death. The cells of the tissues of the body have a certain lifespan, after which they cease to function and they die off, and in their place are born new. Lives of the cells are different, it is genetically programmed and allows the body to maintain a certain level of functionality of their structures.

Apoptos – the mechanism of genetic control of synthesis of substances and cells that respond to the emergence in the process of formation of new cells and extracellular structures of genetic errors, mutations, ie, formation of cells, which should replace the collapsed. The task of apoptose – destruction of mutated cells and the maintenance of their consistency and also body tissues. The involution of organs and tissues after their physiological functions using apoptose.

For example, after the formation of the immune system there is atrophy of the thymus gland and aging of the human organism evidenced by the atrophy of organs and tissues, etc If of the damaging factors affect the genes that control the inclusion process of apoptozu, that this process develops in conditions of pathology. This happens in the case of activation of cytokines, growth factors, hormones, diseases at the molecular level.

Often this is a special property of apoptosis used in Oncology for the collapse of tumor cells. Watching under a microscope, you can see how this process develops. First lost contacts with neighboring cells, and then they decrease in size. Their nuclei become fragmented, there is a disintegration of the cytoplasm and the cell splits into apoptosis Taurus, surrounded by a membrane and is reabsorbed by the surrounding cells, rare macrophages.

Apoptos eliminates the development of inflammatory reactions, in the place of dead tissue cells are reborn new. It is characterized by proliferation in physiological conditions. Changes due to apoptosis natural, evolutionary-driven and genetically regulated mechanism of morphogenesis. It provides differentiation andspecialization of tissues, when present and proliferation, sorting and migration of cells.

Necrosis

If we talk about necrosis, it is quite different processes – necrosis of cells, tissues, individual organs or their parts caused by pathology. Not physiological conditions, as in the case of apoptosis and unfavorable factors contributing to the formation of necrotic phenomena. And when apoptose and necrosis characteristic changes in the cells and intercellular substance, which marks the shrivelling of the nucleus and cytoplasm, fragmentation into clumps and dissolution.

Under the influence of the activation of hydrolytic enzymes of lysosomes is lizirovania. But when necrosis develops intoxication, formed the focus of inflammation and destruction of structural elements of a tissue or organ falls out of the function. The causes of necrosis due to various factors. There are five groups of necrosis:

• traumatic necrosis is the result of a direct action on the fabric mechanical, thermal, radiation, acids, alkalis and etc.;

• toxic necrosis – occurs when the tissue germs and infections;
• trophoneurosis necrosis is caused by disorders of innervation of the tissues in diseases of the Central or peripheral nervous system;
• allergic necrosis is a consequence of the immune reactions;
• vascular necrosis – the result of cessation of circulation of blood in the arteries;

Necrosis dead masses have a different consistency, depending on its structure necrosis happens:

• Coagulative necrosis – thickening of the disintegrated protein observed in muscle tissue and in many internal organs. A variation of this type of necrosis is caseous (cheese) necrosis.
• Colliquation (wet) necrosis develops in tissues rich in fluid.

Necrosis can be direct, when the tissue is damaged by trauma, toxins, different temperatures and indirect in case of death of tissue under the influence of disorders of the blood vessels or nerves. This pathology never occur instantaneously, the process of dying fabrics can be quick or lengthy. To coagulational necrosis include:

• heart attack – a common form of necrosis of internal organs;
• caseous (cheese) necrosis – occurs when tuberculosis, syphilis, leprosy and lymphogranulomatosis;
• waxy or cancerously necrosis – with the defeat of the muscles of the anterior abdominal wall and thigh infections typhoid and typhus fevers, cholera;
• fibrinolynecrosis – affects the connective tissue in rheumatism, rheumatoid arthritis and systemic lupus erythematosus;