92. Regeneration, reparation: definition of concepts, types, biological significance, morphological characteristics.

1. Regeneration - restoration (compensation) of the structural elements of the tissue in place of the dead and its functional capabilities.

Forms of regeneration:

1) cellular form - cell reproduction by mitotic and amitotic pathways

2) intracellular form (organoid and intraorganoid) - an increase in the number (hyperplasia) and size (hypertrophy) of ultrastructures and their components.

Mainly cellular regeneration is characteristic of the epithelium of the skin and mucous membranes, mainly intracellular - for the myocardium, skeletal muscles, ganglion cells of the central nervous system, cellular and intracellular regeneration - for the liver, kidneys, lungs, MMC.

2. Morphogenesis of the regenerative process:

a) the proliferation phase is the reproduction of young, undifferentiated cells (cambial, stem, progenitor cells)

b) differentiation phase - maturation and structural and functional specialization of young cells.

Regulation of regeneration:

1) humoral factors (hormones, poetins, growth factor, keylones)

2) immunological (the fact of lymphocyte transfer of "regenerative information" stimulating the proliferative activity of cells of various internal organs has been established)

3) nervous and

4) functional factors (metered functional load).

Exhaustion, hypovitaminosis, and impaired innervation have a negative effect on the regeneration processes.

3. Physiological regeneration - occurs throughout life, includes:

• renewal of cells, fibrous structures, the basic substance of connective tissue

• updating of intracellular structures

• biochemical regeneration (updating the molecular composition of all body components)

Examples: renewal of cells of mucous membranes and skin, serous membranes, blood.

1. Reparative (restorative) regeneration - restoration of structural elements in various pathological processes leading to damage to cells and tissues:

a) complete regeneration (restitution) - compensation of a defect by a tissue identical to the deceased - mainly in tissues where cellular regeneration prevails (connective tissue, bones, mucous membranes)

b) incomplete regeneration (substitution) - the defect is replaced by connective tissue, a scar, while a compensatory increase in the remaining elements of specialized tissue occurs in its mass (i.e. regenerative hypertrophy) - mainly in tissues where intracellular regeneration prevails or it is combined with cellular regeneration.

Regenerative hypertrophy can be carried out in two ways:

1. hyperplasia of cells (liver, kidneys, pancreas. gland, lungs, spleen, etc.)

2. hyperplasia of ultrastructures (myocardium and neurons of the brain)

2. Pathological regeneration is a perversion of the regeneration process towards hyperregeneration or hyperregeneration, a violation of the phase change of proliferation and differentiation (in fact, this is an incorrectly occurring reparative regeneration).

Examples:

1. Tissues have not lost their regenerative ability, but under physical and biochemical conditions regeneration takes on an excessive character, resulting in tumor-like growths and leading to impaired function (intensive growth of granulation tissue in wounds: excessive granulation, keloid scars after burns, amputation neuromas).

2. Loss of habitual, adequate regeneration rates by tissues (for example, with exhaustion, vitamin deficiency, diabetes) – long-term unhealed wounds, false joints, epithelial metaplasia in the focus of chronic inflammation

3. Regeneration has a qualitatively new character in relation to the tissues that have arisen, this is associated with the functional inferiority of the regenerate (the formation of false lobules in cirrhosis of the liver).