natural regeneration processes. Regeneration, its types and levels

VOLGOGRAD STATE ACADEMY OF PHYSICAL CULTURE

Essay

in biology

on the topic of:

Regeneration, its types and levels. Conditions affecting the course of recovery processes"

Completed: student group 108

Timofeev D. M

Volgograd 2003

Introduction

1. The concept of regeneration

2. Types of regeneration

3. Conditions affecting the course of recovery processes

Conclusion

Bibliography

Introduction

Regeneration - renewal of body structures in the process of life and restoration of those structures that were lost as a result of pathological processes. To a greater extent, regeneration is inherent in plants and invertebrates, and to a lesser extent, in vertebrates. Regeneration - in medicine - the complete restoration of lost parts.

The phenomena of regeneration were familiar to people in ancient times. By the end of the 19th century material has been accumulated that reveals the patterns of the regenerative reaction in humans and animals, but the problem of regeneration has been developed especially intensively since the 1940s. 20th century

Scientists have long been trying to understand how amphibians - for example, newts and salamanders - regenerate severed tails, limbs, jaws. Moreover, their damaged heart, eye tissues, and spinal cord are restored. The method used by amphibians for self-repair became clear when scientists compared the regeneration of mature individuals and embryos. It turns out that in the early stages of development, the cells of the future creature are immature, their fate may well change.

In this essay, the concept will be given and the types of regeneration, as well as the features of the course of recovery processes, will be considered.

1. The concept of regeneration

REGENERATION(from late Latin regenera-tio - rebirth, renewal) in biology, the restoration of lost or damaged organs and tissues by the body, as well as the restoration of the whole organism from its part. Regeneration is observed in natural conditions, and can also be induced experimentally.

R regeneration in animals and humans- the formation of new structures to replace those that were removed or died as a result of damage (reparative regeneration) or lost in the course of normal life activity (physiological regeneration); secondary development caused by the loss of a previously developed organ. The regenerated organ may have the same structure as the removed one, differ from it, or not at all resemble it (atypical regeneration).

The term "regeneration" was proposed in 1712 by the French. scientist R. Reaumur, who studied the regeneration of the legs of crayfish. In many invertebrates, it is possible to regenerate a whole organism from a piece of the body. In highly organized animals, this is impossible - only individual organs or parts of them regenerate. Regeneration can occur through the growth of tissues on the wound surface, the restructuring of the remaining part of the organ into a new one, or through the growth of the remainder of the organ without changing its shape. . The idea of ​​a weakening of the ability to regenerate as the organization of animals increases is erroneous, since the process of regeneration depends not only on the level of organization of the animal, but also on many other factors and is therefore characterized by variability. The assertion that the ability to regenerate naturally decreases with age is also incorrect; it can also increase in the process of ontogenesis, but in the period of old age it often decreases. Over the last quarter of a century, it has been shown that, although entire external organs in mammals and humans do not regenerate, their internal organs, as well as muscles, skeleton, skin, are capable of regeneration, which is studied at the organ, tissue, cellular and subcellular levels. The development of methods for strengthening (stimulating) the weak and restoring the lost ability to regenerate will bring the doctrine of regeneration closer to medicine.

Regeneration in medicine. There are physiological, reparative and pathological regeneration. For injuries etc. pathological conditions, which are accompanied by massive cell death, tissue repair is carried out due to reparative(restorative) regeneration. If in the process of reparative regeneration the lost part is replaced by an equivalent, specialized tissue, they speak of complete regeneration (restitution); if unspecialized connective tissue grows at the site of the defect, it is about incomplete regeneration (healing through scarring). In some cases, during substitution, the function is restored due to the intensive neoplasm of tissue (similar to the deceased) in the intact part of the organ. This neoplasm occurs either through increased cell reproduction, or due to intracellular regeneration - restoration of subcellular structures with an unchanged number of cells (heart muscle, nervous tissue). Age, metabolic characteristics, the state of the nervous and endocrine systems, nutrition, the intensity of blood circulation in damaged tissue, concomitant diseases can weaken, enhance or qualitatively change the regeneration process. In some cases, this leads to pathological regeneration. Its manifestations: long-term non-healing ulcers, impaired healing of bone fractures, excessive tissue growth or the transition of one type of tissue to another. Therapeutic effects on the regeneration process consist in stimulating complete and preventing pathological regeneration.

R regeneration in plants can occur at the site of the lost part (restitution) or at another location in the body (reproduction). Spring restoration of leaves instead of fallen leaves in autumn is a natural regeneration of the reproduction type. Usually, however, regeneration is understood only as the restoration of forcibly torn away parts. With such regeneration, the body primarily uses the main ways of normal development. Therefore, the regeneration of organs in plants occurs predominantly through reproduction: the taken away organs are compensated by the development of existing or newly formed metameric deposits. So, when cutting off the top of the shoot, side shoots develop intensively. Plants or their parts that do not develop metamerically are more easily regenerated by restitution, as are tissue regions. For example, the surface of the wound may become covered with the so-called wound periderm; a wound on a trunk or branch can heal with influxes (callus). Propagation of plants by cuttings is the simplest case of regeneration, when a whole plant is restored from a small vegetative part.

Regeneration from segments of the root, rhizome or thallus is also widespread. You can grow plants from leafy cuttings, pieces of a leaf (for example, in begonias). Some plants succeeded in regeneration from isolated cells and even from individual isolated protoplasts, and in some species of siphon algae, from small areas of their multinucleated protoplasm. The young age of the plant usually promotes regeneration, but at too early stages of ontogeny the organ may be incapable of regeneration. As a biological device that ensures the healing of wounds, the restoration of accidentally lost organs, and often vegetative reproduction, regeneration has great importance for plant growing, fruit growing, forestry, ornamental gardening, etc. It also provides material for solving a number of theoretical problems, including the problems of the development of the organism. Growth substances play an important role in regeneration processes.

2. Types of regeneration

There are two types of regeneration - physiological and reparative.

Physiological regeneration- continuous renewal of structures at the cellular (change of blood cells, epidermis, etc.) and intracellular (renewal of cell organelles) levels, which ensure the functioning of organs and tissues.

Reparative regeneration- the process of elimination of structural damage after the action of pathogenic factors.

Both types of regeneration are not isolated, independent of each other. Thus, reparative regeneration unfolds on a physiological basis, that is, on the basis of the same mechanisms, and differs only in a greater intensity of manifestations. Therefore, reparative regeneration should be considered as a normal reaction of the body to damage, characterized by a sharp increase in the physiological mechanisms of reproduction of specific tissue elements of a particular organ.

The significance of regeneration for the body is determined by the fact that on the basis of cellular and intracellular renewal of organs, a wide range of adaptive fluctuations in their functional activity in changing environmental conditions is provided, as well as restoration and compensation of functions impaired under the influence of various pathogenic factors.

Physiological and reparative regeneration are the structural basis of the whole variety of manifestations of the vital activity of the organism in normal and pathological conditions.

The process of regeneration unfolds at different levels of organization - systemic, organ, tissue, cellular, intracellular. It is carried out by direct and indirect cell division, renewal of intracellular organelles and their reproduction. Renewal of intracellular structures and their hyperplasia are a universal form of regeneration inherent in all organs of mammals and humans without exception. It is expressed either in the form of intracellular regeneration proper, when, after the death of a part of the cell, its structure is restored due to the reproduction of surviving organelles, or in the form of an increase in the number of organelles (compensatory hyperplasia of organelles) in one cell when another cell dies.

The ability of living organisms to regenerate organs is one of the many mysterious mysteries of biology that man has long been trying to solve. Back in 2005, the well-known journal Science published a list of the 25 most important problems in science, which includes the problem unraveling the mystery of organ regeneration.

Pyotr Garyaev. ‹Top Secret» Biology of Youth

Stem cells are the basis of regeneration

To date, scientists have not been able to fully understand- why some living beings, losing a limb, can quickly restore it, while others are deprived of such an opportunity. The whole organism at a certain stage of development knows how to do this, but this stage is very short - a period that begins and immediately ends when the embryo is just beginning to develop. Currently, scientists around the world are trying to find the answer to the question: is it possible to wake up this “valuable” memory in the adult brain and make it work again.

Some experts in the field of regenerative medicine believe that this regeneration function can be restored using. These cells in the body of an adult are contained in a very small amount and are located in the lower spine next to the root node. These are unique cells, with their help the organism of the future little man was born, and then built and developed.

The first eight cells formed as a result of conception, the fertilization of an egg by a spermatozoon, are the original stem cells. Scientists have found out that in order to activate the reproduction of these stem cells, it is necessary to launch a special vortex field (Merka-ba). It will stimulate the active production of stem cells. With the active production of cells, the human body will begin regeneration. This is the cherished dream of scientists of regenerative medicine.

Damage to the spinal cord, any organ or limb is made from a healthy active person disabled for the rest of your life. By completely unraveling the mystery of organ regeneration, scientists will be able to learn how to help such people by “growing” new healthy organs. Also, the regeneration process can significantly increase life expectancy.

Regeneration of organs and tissues: how does it happen?

The Salamander's Healing Immune System

Trying to solve the mystery, scientists closely watched organisms that have these abilities: tadpoles, lizards, molluscs, all crustaceans, amphibians, shrimps.

Especially from this group, scientists distinguish salamander. This individual is able to regenerate, and more than once, the head and dorsal, heart, limbs and tail. It is this amphibian that experts in the field of regenerative medicine around the world consider to be an ideal example of the ability to regenerate.

This process in the salamander is very precise. She can restore a limb completely, but if only a part is lost, then that lost part is restored. At the moment, it is not known exactly how many times a salamander can recover. It should be noted that the once again grown limb is without pathologies and deviations. The secret of this amphibian is the immune system , it is she who helps the restoration of organs.

Scientists are very carefully studying this immune system in order to copy the recovery technique, but for human body. But while copying fails, despite a large number of salamander research. Only scientists from the Australian Institute of Regenerative Medicine claim that they most likely managed to find a fundamental factor in the salamander's ability to regenerate.

• They argue that this ability is based on the cells of the immune system, which are designed to digest dead cells, fungi, bacteria that the body has rejected. Scientists have long experimented on salamanders living in the laboratory. They artificially cleansed the body of amphibians, thereby "turning off" the regenerative abilities. As a result, a scar similar to the human scar that appears after serious injuries simply formed on the wounds;
• Experts believe that it is the cells of the immune system that create special chemicals that form the basis of the regenerative process. Most likely, the chemical is reproduced directly on the damaged area and begins to actively restore it;
• Recently, Australian scientists announced that they are preparing a long-term study of the immune system of humans and salamanders. Thanks to modern equipment and high professionalism of scientists, most likely, in the coming years it will be revealed what exactly helps the rapid regeneration of amphibians;
• Also, along the way, a discovery can be made in the field of cosmetology, prosthetics and transplantology regarding the effective disposal of scars. This problem also for many years he cannot make up his mind;
• Unfortunately, none of them has the ability to regenerate organs. A person's ability to regenerate can be activated only by adding certain special components to the body.

Research on regeneration in mammals

However, there are experts who, after much research and experimentation, claim that mammals can regenerate the tip of the finger. They made these conclusions while working with mice. But, the degree of regeneration is very limited. If we compare the paw of a mouse and a human finger, then it is possible to grow a lost fragment that does not reach the place of the cuticle. If even a millimeter more, then the regeneration process is no longer possible.

There is evidence that a community of scientists from Japan and the United States were able to “wake up” mouse stem cells and grew a large part of a limb equal to the length of an average human finger. They found that stem cells are located throughout the body of a mammal, they multiply and become the cells that, in this moment most necessary for the body to function properly.

Conclusion

Scientists around the world are working hard to find out how the human body can regenerate organs. If, nevertheless, specialists learn to “wake up” stem cells, then this will be one of the greatest discoveries of mankind. This knowledge will greatly affect the work of absolutely all areas of clinical medicine, allowing to “replace”, in the truest sense of the word, worthless, dead organs with healthy ones and effectively restore damaged tissues.

Currently, all research and experiments are carried out with the mandatory participation of mammals and amphibians.

Regeneration (from Latin regeneratio - rebirth) is a process of renewal of all functioning structures of the body (biomolecules, cell organelles, cells, tissues, organs and the whole organism) and is a manifestation of the most important attribute of life - self-renewal. So, physiological regeneration at the cellular and tissue level is the renewal of the epidermis, hair, nails, cornea, epithelium of the intestinal mucosa, peripheral blood cells, etc. According to the isotope method, the composition of atoms human body during the year is updated by 98%. At the same time, the cells of the gastric mucosa are updated in 5 days, fat cells - in 3 weeks, skin cells - in 5 weeks, skeletal cells - in 3 months.

Regeneration in broad sense words - this is the normal renewal of organs and tissues, and the restoration of the lost, and the elimination of damage, and, finally, reconstruction (reconstruction of the organ).

The body has two main strategies for tissue replacement and self-renewal (regeneration). The first way is that differentiated cells are replaced as a result of their formation of new ones from regional stem cells. An example of this category are hematopoietic stem cells. The second way is that tissue regeneration occurs due to differentiated cells, but retaining the ability to divide: for example, hepatocytes, skeletal muscle and endothelial cells.

Regeneration phases: proliferation (mitosis, an increase in the number of undifferentiated cells), differentiation (structural and functional specialization of cells) and shaping.

Types and forms of regeneration

1. Cellular regeneration- this is cell renewal as a result of mitosis of undifferentiated or poorly differentiated cells.

For the normal course of regeneration processes, a decisive role is played not only by stem cells, but also by other cellular sources, the specific activation of which is carried out biologically. active substances(hormones, prostaglandins, poetins, specific growth factors):
- activation of reserve cells that stopped at an early stage of their differentiation and are not involved in the development process until they receive a stimulus for regeneration

Temporary dedifferentiation of cells in response to a regenerative stimulus, when differentiated cells lose their signs of specialization and then differentiate again into the same cell type

Metaplasia - transformation into cells of a different type: for example, a chondrocyte transforms into a myocyte or vice versa (an organ preparation as an adequate determinant stimulus for physiological cell metaplasia).

2. Intracellular regeneration- renewal of membranes, preserved organelles or an increase in their number (hyperplasia) and size (hypertrophy).

3. Biochemical regeneration- renewal of the biomolecular composition of the cell, its organelles, nucleus, cytoplasm (for example, peptides, growth factors, collagen, hormones, etc.). The intracellular form of regeneration is universal, since it is characteristic of all organs and tissues.

Reparative regeneration(from lat. reparatio - restoration) occurs after tissue or organ damage (for example, mechanical injury, surgery, the effect of poisons, burns, frostbite, radiation exposure, etc.). Reparative regeneration is based on the same mechanisms that are characteristic of physiological regeneration.

The ability to repair internal organs is very high: the liver, ovary, intestinal mucosa, etc. An example is the liver, in which the source of regeneration is practically inexhaustible, as evidenced by the well-known experimental data obtained on animals: with a 12-fold removal of a third of the liver within a year in rats by the end of the year, under the influence of organ preparations, the liver restored its normal size.

Reparative regeneration of such tissues as muscle and skeletal has certain features. For muscle repair, it is important to preserve its small stumps at both ends, and periosteum is necessary for bone regeneration. Reparation inducers are biologically active substances released during tissue damage. In addition, individual fragments of the same damaged tissue can act as inductors: a complete replacement of a defect in the bones of the skull can be obtained after the introduction of bone filings into it.

Reparative regeneration can take two forms.

1. Complete regeneration - the site of necrosis is filled with tissue identical to the deceased, and the site of damage disappears completely. This form is typical for tissues in which regeneration proceeds mainly in the cellular form. Complete regeneration can be attributed to the restoration of intracellular structures during cell dystrophy (for example, fatty degeneration of hepatocytes in people who abuse alcohol).

2. Incomplete regeneration - the area of ​​necrosis is replaced connective tissue, and the normalization of the function of the organ occurs due to hyperplasia of the remaining surrounding cells (myocardial infarction). This method takes place in organs with predominantly intracellular regeneration.

prospects scientific research on regeneration. Currently, organ preparations are being actively studied - extracts of the contents of a living cell with all its important cellular macromolecules (proteins, bioregulatory substances, growth and differentiation factors). Each tissue has a certain biochemical specificity of cellular content. Due to this, a large number of organ preparations are produced with a targeted focus on certain tissues and organs.

In general, the direct effect of organ preparations, as standards of cell biochemistry, is primarily to eliminate the cellular imbalance of bioregulators of regeneration processes, to maintain the balance of optimal concentrations of biomolecules and to maintain chemical homeostasis, which is disturbed not only under conditions of any pathology, but also during functional changes. This leads to the restoration of mitotic activity, cell differentiation and tissue regenerative potential. Organic preparations provide the quality of the most important characteristic of the process of physiological regeneration - they contribute to the appearance in the process of division and differentiation of healthy and functionally active cells that are resistant to environmental toxins, metabolites and other influences. Such cells form a specific microenvironment, characteristic of this type of healthy tissue, which has a depressing effect on existing "plus-tissues" and prevents the appearance of malignant cells.

So, the effect of organ preparations on the processes of physiological regeneration is that, on the one hand, they stimulate immature developing cells of homologous tissue (regional stem cells, etc.) to normal development into mature forms, i.e. stimulate the mitotic activity of normal tissues and cell differentiation, and on the other hand, normalize cellular metabolism in homologous tissues. As a result, physiological regeneration occurs in the homologous tissue with the formation of normal cell populations with optimal metabolism, and this whole process is physiological in nature. Due to this, in case of damage to an organ (for example, skin or gastric mucosa), organ preparations provide an ideal repair - healing without a scar.

It should be emphasized that the restoration of mitotic activity and cell differentiation under the influence of organ preparations is the key to correcting defects and anomalies in the development of organs in children.
Under conditions of pathology or accelerated aging, physiological regeneration processes also take place, but they do not have such a quality - young cells appear that are not resistant to circulating toxins, do not perform their functions sufficiently, are not able to resist pathogens, which creates conditions for the preservation of the pathological process in the tissue or organ, for the development of premature aging. Hence, the expediency of using organ preparations as means that can most effectively restore the regenerative potential and biochemical homeostasis of tissue, organ and the whole organism and thus prevent the aging process is understandable and obvious. And this is nothing but revitalization.

Regeneration is the process of repairing damage. This process underlies the restoration of damage to organelles and cells. Therefore, depending on the level of regeneration, intracellular and cellular regeneration are distinguished.

When an individual cell is damaged, for example, mitochondria are well restored. If many cells are damaged, then recovery is possible due to cell multiplication. However, in the course of evolution, this ability to reproduce was formed differently in different cells.

The mechanisms of regeneration are associated with a violation of contact inhibition by a decrease in the number of chalons in cells and the formation of special chemical substances- trefonov, stimulating cell reproduction. Keylons usually cause inhibition of proliferation. When cells are damaged, the number of chalons in them decreases, and they acquire the ability to reproduce.

The epithelium, vascular endothelium, fibroblasts, cells of the bone marrow, lymphoid nodes, bone cells, periosteum are well regenerated, liver cells, cells of the endocrine glands, epithelium of the tubules of the kidneys can be regenerated.

Limited regenerative capacity is characteristic of myofibrils of skeletal and smooth muscle cells.

Practically do not regenerate nerve cells. Regeneration is possible if the axons of the nerve cell (nerves) are damaged, but this process is very slow. This option is possible, i.e. the distal end of the nerve (for example, after trauma or transection) regenerates. If the neurolemma is aligned with the axon growth section in the distal direction, regeneration proceeds at a rate of 20 mm per week.

Due to the fact that in the damaged area, recovery is not due to specialized cells, but due to epithelial, endothelial, fibroblasts, recovery often occurs with the formation of a connective tissue, and if nerve cells are damaged, a glial scar. Therefore, in muscles, nervous tissue, and in

In other organs, restoration (healing) of the damaged area occurs due to the formation of a scar.

hypertrophy and hyperplasia

Hyperplasia is a component of hypertrophy and is characterized by an increase in the number of structural elements of the cell, for example, mychotondria, lysosomes, endoplasmic reticulum, etc. Hypertrophy (hyper - increase, trophe - nourish) is characterized not only by an increase in intracellular organelles, the cell itself, but also the organ as a whole. Depending on the origin, it is divided into physiological and pathological. Physiological hypertrophy is observed in athletes (hypertrophy of the striated muscles and heart), pregnant women and women in childbirth (hypertrophy of the uterus and mammary glands). Pathological hypertrophy occurs when the cells of an organ are damaged or the functional load increases, for example, hypertrophy of the heart (with myocardial infarction), a paired organ (removal of a kidney, lung).

The mechanism of hypertrophy is based on energy deficiency with subsequent activation of the genetic apparatus of the cell. As a result, protein synthesis is enhanced, mitochondrial hyperplasia occurs and an improvement in the formation of macroergs, with a further strengthening of synthetic processes in the cells of the organ.

Atrophy is such a process in a cell, which is characterized by a decrease in the size of not only all its organelles, but also the cell itself, which is usually associated with a lack nutrients, a decrease in the functional load and regulatory influences.

By origin, it is divided into physiological and pathological.

Physiological atrophy is observed with age in various human tissues and organs (skin, mucous membranes, gonads, etc.). Under conditions of pathology, atrophy is observed during starvation (in fat and muscle cells), with peripheral (atrophic) paralysis, in peripheral endocrine glands with a deficiency of thyrotropin, corticotropin, gonadotropins. Muscle atrophy also develops during physical inactivity (for example, it is possible in astronauts) or in immobilized patients. In addition, it is formed when the motor nerve is transected (peripheral paralysis).

Thus, in its classical form, pathological atrophy develops with nutritional deficiencies, movement restriction, denervation, and dysregulation of peripheral glands. To this it should be added that if atrophy can be considered as a compensatory process in the above conditions at the cell level, then at the organ, system and organism level it is a factor of damage and causes serious disorders.

So, as a result of the direct action of the damaging factor or the involvement of the above general mechanisms of damage, the structure of the cell is disturbed. The main morphological signs of damage are: dystrophy, dysplasia, disruption of the structure of intracellular organelles, necrobiosis and necrosis. At the same time, the function of the cell also changes. For example, the phagocytic activity of leukocytes decreases, the resting and action potential changes, which can be manifested by a change in the electrocardiogram, myogram, encephalogram, etc.

Dystrophy (dis - disorder, trophe - nourish) - a process that occurs in cells and tissues, which is based on malnutrition of cells, is characterized by quantitative and qualitative changes in metabolic processes.

The basis of dystrophy of any origin is dysregulation of nutrition (trophism) of the cell. Depending on the nature of metabolic disorders, the following dystrophies are distinguished: protein, carbohydrate, fat and mineral. Dystrophic processes can occur both in specialized cellular elements of the parenchyma and in the stroma. Depending on the prevalence of dystrophy can be local or systemic.

Protein degeneration is associated with excessive accumulation of protein in cells or intercellular substance. The accumulation of protein in the parenchyma can be manifested by the formation of granularity, hyaline drops, vacuoles. In the mesenchyme, this is manifested by mucous edema, fibrinoid changes, fibrinolysis, accumulation of hyaline and amyloid. For example, in amyloid degeneration, which occurs with chronic inflammation or monoclonal proliferation of plasma cells, with tumors of the endocrine glands with excessive secretion, for example, calcitonin, insulin. Usually, amyloid A or L can accumulate in these cases.

As a rule, all tissues and organs are affected, but especially the kidneys, gastrointestinal tract and heart. Moreover, amyloid accumulates around the capillaries and along the way muscle fibers in the basement membrane of the renal tubules. Due to mechanical pressure, atrophy of cells (tubules, cardiomyocytes) occurs, and capillary permeability increases. As a result, a large amount of protein is lost in the kidneys due to increased capillary permeability and impaired reabsorption with urine, and absorption is impaired in the gastrointestinal tract. Therefore, diarrhea develops with the loss of large amounts of fluid, nutrients and electrolytes. In cardiomyocytes, wrinkling and a violation of their contractility occur. Thus, amyloidosis, in turn, is the most important link in further cell damage.

Mixed forms of proteinaceous dystrophies are associated with the accumulation of such complex products as hemosiderin, melanin, bilirubin, nucleoprotein, glycoprotein. Such dystrophies develop with hemolysis of red blood cells, jaundice, gout. For example, melanin is a pigment and is normally found in the skin, iris, and adrenal glands. It is formed by melanocytes, captured by epithelial cells, and they become darker.

Melanin is destroyed by melanophores, which phagocytize it. The accumulation of melanin in cells can be local, for example, with tumors such as melanoma or during pregnancy, when age spots appear on the face. The generalized nature of pigmentation is possible, for example, with ultraviolet irradiation or primary adrenal insufficiency. The mechanism of such systemic changes is due to excessive secretion of pituitary melanotropin, which stimulates melanocytes.

Fatty degeneration or lipidosis. It is characterized by a change in the amount of neutral fat. This, as a rule, is manifested by an increase (obesity) or a decrease (weight loss, cachexia) in the amount of fat not only in fat depots, but also in other organs. Local depletion of adipose tissue (lipodystrophy) is observed in the area of ​​subcutaneous insulin administration, with atrophy of the organ.

Especially often a violation of lipid metabolism, as well as protein metabolism, occurs in organs such as the kidneys, heart, liver. In old age, with diabetes, systemic obesity, fatty degeneration develops in vascular endothelial cells (atherosclerosis, where lipids are deposited in the intima, forming a plaque that undergoes fibrosis).

Carbohydrate dystrophy is associated with impaired metabolism of complex carbohydrates such as poly-, mucopolysaccharides, glycoproteins.

In the classical version, this type of dystrophy is associated with a change in the amount of such a polysaccharide as glycogen. Its content in cells can increase with the so-called. hereditary enzymopathies, when, due to a violation of the formation of enzymes (for example, glucose-6-phosphatase), glycogen is deposited in the cell, but cannot be mobilized. These dystrophic changes are called glycogenoses. They are usually characterized by a sharp increase in the liver and kidneys and a decrease in the amount of glucose in the blood.

On the other hand, when fasting diabetes the content of glycogen in cells decreases sharply. The content of glycoproteins in the form of mucins increases in the cell with a lack of thyroid hormones. A large accumulation of mucins leads to mucous edema, one of the most characteristic manifestations of myxedema.

Mineral dystrophies are associated with impaired metabolism of iron, copper, potassium, and calcium. The accumulation of these minerals (iron, copper, potassium, calcium) in the cells is observed in hemosiderosis, hepatocerebral dystrophy, calcification, and corticosteroid insufficiency.

Loss of calcium by bone cells is the basis of osteoporosis.

Dysplasia (dis - disorder, plaseo - form). This is such a violation of the cell, which is based on a violation of its genome, the consequence of which is a persistent change in the structure and function of the cell. At the forefront is a violation of cell differentiation. Therefore, both the structure and function of such a cell differs from the parent. Dysplasia is most characteristic of tumor cells, which, in the course of tumor progression (selection), change their size, shape, number of organelles, and activate biochemical processes. Such cells, multiplying, are able to infiltrate healthy tissues and metastasize. Violations of intracellular organelles can manifest themselves in a change in their structure, number and, consequently, their functional activity.

Necrosis. As a result of the direct action of the destructive factor on the cell membrane, or with a slight change in its permeability, sodium and calcium ions, water first of all enter the cell, and it swells. Swelling is also noted on the part of intracellular organelles, followed by rupture of their membranes, disintegration and cell death. The death of a part of the cells of an organ or tissue in a living organism is called necrosis. In this case, activated enzymes and potassium enter the bloodstream and can be used as a diagnostic test.

There are two types of necrosis:

1. Coagulation.

2. Colliquation.

Coagulative necrosis is associated with a cessation of blood flow (heart attack) and is microscopically characterized by changes in the nucleus such as karyolysis or karyorrhexis, the cytoplasm, which becomes opaque due to protein coagulation. Depending on the nature of circulatory disorders (ischemia or venous hyperemia), the infarction is called ischemic or venous (congestive).

Colliquational necrosis occurs in organs containing a large amount of fluid, the presence of which contributes to the activation of lysosomal enzymes that lyse the components of the cell with a complete violation of its structure, as a result of which the necrotic area undergoes softening. A classic example of such necrosis is an abscess, necrosis of the intestine, brain cells.

If cells after necrosis undergo self-digestion under the action of activated enzymes, this process is called autolysis. They can also be resorbed under the influence of the phagocytic activity of leukocytes.

A complication of necrosis is gangrene, in which the necrotic area undergoes mummification or exposure to microorganisms that cause putrefaction. In this case, in the latter case, unpleasantly smelling gases are formed, and the gangrene area becomes black due to the breakdown of hemoglobin. Gangrene usually develops against the background of impaired blood circulation, (for example, with diabetes on the foot; in the intestines with its volvulus or intussusception). When infected with a special organism, gas gangrene occurs.

If only individual cells surrounded by healthy ones die, this phenomenon is called necrobiosis. In this case, due to active metabolic processes in the cell, destruction of the nucleus, cytoplasm and even cellular disintegration occurs. Nearby cells phagocytize decay products. This is a physiological process, and therefore inflammation does not develop. In pathological conditions, this phenomenon is observed in atrophy and in tumors.

Regeneration is physiological, reparative And pathological. The process of regeneration is very close, in fact identical to the hyperplastic process (multiplication of cells and intracellular structures). They differ in that hyperplasia (hypertrophy) usually occurs in connection with the need to strengthen the function, and regeneration - with the "goal" of normalizing the function in case of damage to the organ and the loss of part of its mass. Previously, it was believed that regeneration was limited only to the organ and tissue levels. Now it has become obvious that physiological and reparative regeneration is a universal phenomenon, inherent not only at the tissue and cellular levels, but also at the intracellular, including the molecular level (regeneration of the damaged DNA structure). So, after pathogenic influence and damage to DNA, its “healing” occurs, carried out by the consistent work of reparative enzymes. They "recognize" the damaged area, expand it, i.e. as if they clean the place of damage, and then “build up” the resulting gap along the complementary intact DNA strand and “sew” the built-in nucleotides. The most remarkable thing about the process of DNA repair is that it, as it were, repeats in miniature those main links of the regenerative process that we are accustomed to observing when it is deployed at the tissue level - damage, enzymatic cleavage of dead tissues and cleansing of the damaged area within healthy tissues, filling formed defect with a newly formed tissue of the same type (complete regeneration) or connective tissue (incomplete regeneration). This indicates that with all the seemingly endless variety of processes unfolding in the body, each of them, in principle, proceeds according to some universal, common for all levels of organization, typical scheme.

Regeneration, proceeding at the molecular and ultrastructural levels, is limited to cells, and therefore it is called intracellular. Structural support of the body's adaptation to everyday influences environment provided by the corresponding intensity fluctuations physiological regeneration , which in case of illness increases sharply and takes on the character reparative. Both physiological and reparative regeneration in some organs is provided by all its forms - cellular (mitosis, amitosis) and intracellular. In organs and systems such as the central nervous system and the heart (myocardium), where cell reproduction is absent, the structural basis for the normalization of their function is exclusively intracellular regeneration. Thus, the latter is a universal form of regeneration, characteristic of all organs without exception.

Reparative regeneration is complete, incomplete and intracellular.

cell form regeneration is inherent in the following organs and tissues (bone, hematopoietic, loose connective, endothelium, mesothelium, mucous membranes of the gastrointestinal tract, genitourinary system, respiratory organs, skin, lymphoid tissue),

To organs and tissues, where intracellular form of regeneration, include myocardium and nerve cells.

In some organs, a cellular and intracellular form of regeneration is observed - the liver, kidneys, lungs, smooth muscles, endocrine glands, pancreas, autonomic nervous system.

The morphogenesis of the reparative process consists of two phases - proliferation and differentiation. The first phase is the reproduction of young undifferentiated cells (cambial, stem or progenitor cells). Reproducing and then differentiating, they make up for the loss of highly differentiated cells. There is another point of view about the sources of regeneration. It is assumed that highly differentiated cells of an organ can be a source of regeneration, which under the conditions of a pathological process can be rebuilt, lose some of their specific organelles and simultaneously acquire the ability to mitotic division with subsequent proliferation and differentiation. The outcomes of the regeneration process may be different. In some cases, reparative regeneration ends with the formation of a part identical to the deceased - then they talk about complete regeneration or restitution. In others, incomplete regeneration (substitution) occurs. In the area of ​​damage, not a specific tissue for this organ is formed, but a connective tissue, which is subsequently subjected to scarring. At the same time, the remaining structures compensatory increase in their mass, i.e. hypertrophied. There is regenerative hypertrophy, which is the expression of the essence of incomplete regeneration. Regenerative hypertrophy can be carried out in two ways - cell hyperplasia (liver, kidneys, burning iron, lungs, spleen, etc.) and ultrastructures (cell hypertrophy - myocardium and brain neurons). Completely regenerate mainly those tissues that are characterized by cellular regeneration, incompletely regenerate striated muscles, myocardium, large vessels. Regeneration. Hypertrophy is observed in the liver, lungs, kidneys, endocrine glands, ANS.

pathological regeneration- perversion of the regeneration process towards hyporegeneration or hyperregeneration, in fact, this is an incorrectly proceeding reparative regeneration. Examples of such regeneration and their causes are:

1. The tissues have not lost their regenerative capacity, but according to physical and biochemical conditions, regeneration takes on an excessive character, resulting in tumor-like growths and leading to functional impairment (intensive growth of granulation tissue in wounds /excessive granulation/, keloid scars after burns, amputation neuromas).

2. Loss of habitual, adequate rates of regeneration by tissues (for example, with exhaustion, beriberi, diabetes) - long-term non-healing 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 / for example, the formation of false lobules in liver cirrhosis /, and sometimes its transition to a new qualitative process - a tumor.

Regeneration carried out under the influence of various regulatory mechanisms:

1) humoral (hormones, poetic factors, growth factor, keylons)

2) immunological (the fact of the transfer of "regeneration information" by lymphocytes that stimulates the proliferative activity of cells of various internal organs has been established

3) nervous and

4) functional (metered functional load).

The efficiency of regeneration processes is largely determined by the conditions in which it takes place. The general state of the body is of great importance in this respect. Exhaustion, hypovitaminosis, impaired innervation, etc., have a significant effect on the course of reparative regeneration, slowing it down and turning it into a pathological one. A significant influence is exerted by the degree of functional load, the correct dosing of which promotes regeneration (restoration of bone tissue in fractures). The rate of reparative regeneration is to a certain extent determined by age, constitution, metabolism, and nutrition. Local factors are also important - the state of innervation, blood and lymph circulation, the nature of the pathological process, and the proliferative activity of cells.

Wound healing occurs according to the laws of reparative regeneration. Depending on the depth of the defect, the type of tissue and methods of treatment, 4 types of wound healing are distinguished.

1. Direct closure of an epithelial defect, in which epithelial cells creep onto the surface of the defect from the region of the edges of the damage.

2. Healing under the scab occurs in small defects, on the surface of which a crust (scab) is formed, under which epithelial cells grow within 3-5 days, after which the crust disappears.

3. Primary Tension.

4. secondary tension.

Healing by primary intention occurs in the area of ​​treated and sutured skin wounds or small defects of organs and tissues, in which, due to weak tissue trauma and small microbial invasion, dystrophic and necrotic changes in cells and fibers are minimal even at the ultrastructural level. The primary reaction of labrocytes and microcirculation vessels is relatively weak, so the exudation is moderate and has a serous character, the neutrophilic and macrophage stages of the inflammatory cellular reaction are weakened due to the low concentration of mediators that determine the chemotaxis of these cells. This leads to a rapid cleansing of the wound and the transition to the proliferative phase - the appearance of fibroblasts, neoplasm of capillaries, then argyrophilic and collagen fibers. The granulation tissue, which is weakly expressed at primary tension, matures quickly (10-15 days). The surface of the defect is epithelialized and a delicate scar is formed at the site of the wound.

Healing by secondary intention occurs with large and deep, open defects, with active microbial invasion through suppuration. On the border with dead tissue, demarcation purulent inflammation develops. Within 5-6 days, rejection of necrotic masses occurs (secondary cleansing of the wound) and granulation tissue begins to form at the edges of the wound. Granulation tissue, gradually filling the wound defect, has pronounced signs of inflammation and a complex six-layer structure, described by N.N. Anichkov:

1. superficial leukocyte-necrotic layer

2. superficial layer of vascular loops

3. layer of vertical vessels

4. ripening layer

5. layer of horizontal fibroblasts

6. fibrous layer.

Atrophy(a-exception, trophe-food) – a decrease in the volume of cells, tissues, organs with a decrease or cessation of their function. A decrease in the volume of tissues and organs occurs with atrophy due to parenchymal elements. Atrophy must be distinguished from hypoplasia- congenital underdevelopment of organs and tissues.

Atrophy is usually divided into physiological and pathological, local and general.

Physiological atrophy occurs throughout a person's life. So, with age, atrophy: the thymus gland, sex glands, bones, intervertebral cartilage.

Pathological atrophy occurs with circulatory disorders, nervous regulation, intoxication, the action of biological, physical and chemical factors, with malnutrition.

General atrophy appears exhaustion. At the same time, there is a pronounced decrease in body weight, dryness and flabbiness of the skin. Subcutaneous fat is practically absent. There is also no fatty tissue in the greater and lesser omentum, around the kidneys. Its remaining parts have a brown-brown color due to the accumulation of lipochromes. In the liver and myocardium, the phenomena of brown atrophy with the accumulation of lipofuscin in their cells. Internal organs, endocrine glands are reduced in size.

The following types of malnutrition are distinguished: 1. alimentary malnutrition, which develops during starvation or impaired absorption of food; 2. exhaustion in cancer cachexia /most often in cancer of the stomach and other parts of the gastrointestinal tract/; 3. exhaustion with pituitary cachexia (Simmonds disease with destruction of the adenohypophysis); 4. exhaustion in cerebral cachexia that occurs in senile forms of dementia, Alzheimer's and Pick's diseases, due to the involvement of the hypothalamus in the process; 5. exhaustion in other diseases, more often in chronic infections: tuberculosis, chronic dysentery, brucellosis, etc.

There are the following types of local atrophy:

1. Dysfunctional atrophy (from inactivity), resulting from a decrease in the function of an organ, due to its lack of demand. An example of such atrophy is muscle atrophy in case of bone fractures, bone tissue of the alveolar processes of the jaws after tooth extraction.

2. Atrophy due to insufficiency of blood supply - occurs due to narrowing of the lumen of the vessels that supply blood to a given organ or tissue. Examples are: atrophy of the kidneys due to hyalinosis of arterioles in hypertension, brain atrophy in atherosclerosis of the cerebral arteries.

4. Neurotic atrophy occurs when tissue innervation is disturbed in diseases and injuries of the central nervous system and peripheral nerves: atrophy of the soft tissues of the arm with damage to the brachial nerve, atrophy of the striated muscles in people who have had poliomyelitis.

1. Atrophy from the action of chemical and physical factors. Thus, radiation causes atrophy of the bone marrow and sex glands. Prolonged use of ACTH causes atrophy of the adrenal cortex, insulin - atrophy of the islets of Langerhans of the pancreas.

Atrophied organs, when examined with the naked eye, are usually reduced. Their surface is smooth or granular. With the accumulation of lipofuscin in an atrophied organ, they speak of brown atrophy, which occurs in the myocardium and liver.

Atrophy in the early stages of development is a reversible process, and if its cause is eliminated, the function of the organ can be restored.