Age changes and their patterns
Heterochronicity is the difference in the time of onset of destructive processes in tissues, organs and systems of organs of one organism. For example: external signs of skin aging begin to appear from the age of 20, and age-related changes in the eyes are often recorded after 40 years.
Heterotrophy is a different expression for different organs and different tissues of the same organ in the body. For example: the same person can have pronounced age-related changes in the stomach, accompanied by atrophic processes and, at the same time, the structure and functional parameters of the respiratory organs can be quite preserved.
Hetero kineticity is a different rate of development of the destructive processes of individual organs and systems. So, the skin grows old within 40-50 years, and old age changes in the central nervous system can progress for 10-15 years.
Heterocathetenness is a multidirectional process associated with the suppression of the functional activity of some cells and the stimulation of other structural elements. For example: glandular gonad cells produce less male or female sex hormones (respectively) with age, and the level of "tropic" hormones produced by the anterior pituitary gland increases.
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General mechanisms of aging
The general mechanisms of aging are influenced by two mutually opposite processes, which are in dialectical unity: aging and vitaukta. Aging leads to extinction of the intensity of metabolism, a decrease in functionality and at the same time activates adaptive reactions - the process of vitaukt. This provision underlies the adaptation-regulatory theory of aging (VV Frolkis). And the life expectancy depends on the relationship between the processes of stabilization and destruction.
Aging tissues is characterized by such processes as atrophy, an increase in the amount of connective tissue or intercellular substance, the deposition of metabolic products (pigments, calcium, etc.), the appearance of fatty degeneration. The primary aging cells include nerve and connective tissue cells; muscular and glandular age as a result of increasing, with the passage of time, damaging effects and age-related changes in regulatory influences; aging of the epidermis and epithelium is due to the whole complex of internalorganic influences (circulatory, nervous and humoral regulation, etc.).
The age-related changes in the adaptive-regulatory mechanisms of the body take place in three stages:
- maximum voltage for maintaining the range of adaptive capabilities;
- a decrease in reliability: the adaptive capacity of the organism decreases while maintaining the level of basic metabolism and functions;
- decrease in basic metabolism and body functions and a sharp limitation of the range of adaptability.
The concept of age in gerontology
Each person can be identified the following types of age.
- Biological - reflects the functional state of organs and systems, determines the long-term ability to adapt and the reliability of the organism (a measure of the impending ability to live).
- Calendar - the number of years lived by a person from the moment of birth.
- Psychological - a person's sense of belonging to a particular group, reflects the ability of an individual to objectively assess the functional state of his body.
Age changes in each person are genetically programmed (determined by the species life expectancy, hereditary information, possible mutations, etc.), but it is not inevitably predetermined, because the acceleration or slowing down of the aging process depends on both the individual and the environment. Age changes can be natural (biological age corresponds to calendar), slowed down (leading to longevity) and accelerated (the severity of structural and functional processes in the body outstrips the calendar age). Age changes of various organs and systems are significantly expressed in the senile period.
Complex assessment of the functional state of people of the "third" age includes the determination of the state of the following groups of parameters.
- Daily activities:
- useful daily activities, i.e. The ability to be an active member of a society cope with domestic work;
- daily physical activity, i.e. Perform basic self-service activities.
- Mental activity, including:
- cognitive activity;
- severity of intellectual activity violations.
- Psychosocial activity, i.e. Emotional well-being in a social and cultural context.
- Physical health, including:
- the state of health according to one's own assessment;
- physical symptoms and diagnosed conditions;
- frequency of use of health services;
- level of activity and self-service insolvency assessment.
- Social resources:
- the presence of family, friends, familiar surroundings;
- availability of these resources if necessary.
- Economic resources, which are usually estimated using a comparison of revenues with an external indicator, such as the level of poverty.
- Environmental resources, including:
- adequacy and accessibility of housing;
- remoteness of the dwelling from those and other types of transport, shops and public service enterprises.
In geriatrics, in order to evaluate the effectiveness of treatment and prophylactic measures and actively monitor the health of patients, it is necessary to determine the biological age (BV) as a measure of the viability of the organism and compare it with the due biological age (DVV - the population standard of the aging rate according to VP Voitenko and AV Tokar). The development of accessible, informative, safe methods for determining BV and DBW is an urgent task of gerontology.
Age-related changes in organs and systems
Changes in the respiratory system
In the respiratory tract:
- atrophy of the mucous membrane of the upper respiratory tract;
- deceleration of the movement of the villi of the epithelium;
- reduction of glands secretion, increase of its viscosity;
- the appearance of areas where the multilayer ciliated epithelium is replaced by a multilayered epithelium;
- an increase in the threshold of the cough reflex,
- decreased self-purification of the respiratory tract (slowing mucociliary clearance and reducing the effectiveness of immune reactions);
- widening the larynx lumen, reducing the tension of the vocal cords (the voice drops and becomes jarring);
- displacement of the larynx down (on average per vertebra).
In the respiratory departments:
- interzhelveolar septa are destroyed, alveolar tracts expand - senile emphysema develops (increased airiness of lung tissue);
- In the interalveolar septa connective tissue proliferates - pneumosclerosis is formed;
- the vessels of the lungs change, their blood filling decreases;
- the volume of dead space and the residual volume increase;
- the vital capacity of the lungs decreases;
- disturbances of gas exchange lead to a decrease in the arterial blood oxygen content (hypoxemia);
- breathing increases to 22-24 per minute in senile age.
Age-related changes in the musculoskeletal skeleton of the thorax:
- the mobility of the costal-vertebral articulations decreases;
- Calcium salts are deposited in the hyaline cartilages of the ribs;
- weaken muscles (due to dystrophic changes);
- increased thoracic kyphosis;
- the thorax loses its elasticity, its antero-posterior diameter becomes equal to the transverse (the shape of the chest approaches cylindrical).
Age-related changes in the cardiovascular system
Age changes in the heart muscle:
- reduces the contractility of the myocardium; expand the heart cavity and the opening between them, increase the terminal systolic and diastolic volumes;
- heterotrophic hypertrophy of cells develops, their contractility decreases, the isometric contraction phase is extended, the relaxation index decreases;
- the systolic and minute volume of blood decreases (even under normal conditions the heart works with a considerable voltage); the connective-tissue stroma increases (cardiosclerosis develops), myocardial dilatability decreases:
- develops weakness of the sinus node (pacemaker of the first order), slows the excitation of the myocardium - increases the duration of systole, the number of muscle contractions becomes less frequent;
- the intensity of tissue respiration decreases, anaerobic decomposition of glycogen is activated, which leads to a decrease in the energy reserve of the heart muscle;
- in deep old age the muscle fibers atrophy, may develop substitutional obesity.
Age changes in the vascular bed:
- decreases the elasticity of the arteries due to the compaction of their walls with an enlarged connective tissue - increases the vascular resistance and the level of diastolic pressure;
- food deteriorates, energy metabolism in the vascular wall decreases, sodium content in it increases, which leads to activation of the atherosclerotic process, propensity to vasoconstriction (narrowing of the lumen of blood vessels);
- the tone and elasticity of the venous wall decreases, the venous channel widens, the blood flow in it is slowed down (blood return to the heart is reduced, the risk of thrombosis is high);
- the number of functioning capillaries decreases - they become sinuous, the arteriovenous blood shunting increases (blood from the arterial channel passes directly into the veins through the anastomoses, bypassing the capillaries), the basement membrane of the capillaries thickens, making the transport of substances through it more difficult;
- Lymphatic vessels become less elastic, expansion sites appear in them;
- the cerebral and coronary circulation is reduced to a lesser degree than the hepatic and renal;
- With aging, the sensitivity of receptors of blood vessels to adrenaline rises, leading to frequent development of spastic reactions and contributing to sharp changes in blood pressure;
- the time of the general circulation of blood increases because of the increase in the capacity of the vascular bed and the reduction of cardiac output.
Decreased adaptive function of the cardiovascular system, largely due to the inferior work of the hemodynamic center (at cortical, diencephalic and stem levels). Certainly, reflex reactions of the cardiovascular system to stimuli of various kinds-muscular activity, stimulation of interoceptors (change in body position, eye-cardiac reflex), light, sound, pain stimulation-in old people arise with a large latent period, much less expressed, characterized wavy and protracted course of the recovery period.
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Age-related changes in the digestive system
Age changes in the oral cavity:
- there is a gradual loss of teeth, the teeth acquire a yellowish tint and a different degree of erasure, the barrier properties of the tooth tissues decrease;
- Atrophy of the alveolar processes of the jaws, the bite changes (becomes prognathic);
- the volume and secretion of the salivary glands decreases - this leads to a constant feeling of dryness in the mouth, a violation of the formation of the food lump, a tendency to inflammation of the mucous membrane;
- the enzymatic saturation and protective properties of saliva decrease;
- mastication and digestion of food is disturbed;
- the tongue becomes flat and smooth due to the atrophy of the muscles and papillae; the thresholds of taste sensitivity increase.
Gradually atrophy of the tonsils of the lymphoepithelial pharyngeal ring;
The esophagus is elongated and curved because of the spinal kyphosis, its muscular layer undergoes partial atrophy, which can lead to impaired swallowing and a high risk of the formation of hernias (protrusions);
The stomach decreases in size, assumes a position closer to the horizontal. Reduces the number of secretory cells in the glands (less produced hydrochloric acid, enzymes and gastric juice in general). The blood supply to the stomach wall is impaired, and its motor function is reduced.
In the small intestine, the relief of the mucous membrane is smoothed by reducing the height of the villi and their number per unit area (the surface wall digestion and absorption are reduced); due to a decrease in the secretion of digestive juices and their enzymatic saturation, the depth and completeness of food processing is disrupted.
In the large intestine, due to the atrophy of muscle cells, the risk of developing diverticula is high, a tendency to constipation develops; changes in the intestinal microflora: the number of putrefactive bacteria increases, and lactic acid decreases, which promotes the growth of endotoxin production and the synthesis of vitamins of group B and K.
Liver: With age, weight decreases, functional capacity of hepatocytes decreases, which leads to violation of protein, fatty, carbohydrate and pigment metabolism, decrease in antitoxic (detoxifying) liver function. In cells, the amount of glycogen decreases, lipofuscin accumulates, the blood flow in the liver changes: a part of the sinusoidal capillaries subside, additional paths from the interlobular veins to the central veins are formed.
The gall bladder increases in volume, muscle tone and motor activity of the bladder decrease - the timely delivery of bile to the intestine is disrupted and the risk of calcification due to stagnation of bile is increased.
The pancreas reduces the external and intrasecretory function due to a decrease in blood supply and a decrease in the number of glandular cells and cells of the islet apparatus (in older people, a higher blood glucose level).
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Age-related changes in the organs of urination
Age changes in the kidney:
- the number of functioning nephrons decreases (by age 1 / 3-1 / 2), age-related nephrosclerosis is formed;
- the level of renal circulation, glomerular filtration decreases, the excretory (nitrogen, water, electrolyte excretory) and concentration (due to the decrease in the tubular part of the nephron) of the kidney function decrease;
- weakens the ligamentous apparatus of the kidneys as a phenomenon of splanchnoptosis (omission of internal organs).
Age changes in the urinary tract:
- kidney cups and pelvis lose elasticity, speed and strength of movements (due to atrophy of a part of muscle fibers);
- ureters dilate, elongate, become more convoluted, their wall thickens, evacuation of urine from the upper urinary tract slows;
- the violation of the motor function of the urinary tract and the imperfection of physiological sphincters cause frequent reflux in old age (reverse (against the normal direction) urine current);
- the wall of the bladder thickens, its capacity decreases, the inhibitory effect of the cerebral cortex on the bladder receptors during night sleep decreases (along with an increase in nocturnal diuresis associated with processes in the cardiovascular system) to an increase in the frequency of urination at night. Often develop different types of urinary incontinence:
- stress type - with coughing, laughing, exercises associated with increased intra-abdominal pressure;
- the incentive type is the inability to delay the contraction of the bladder (due to a violation of the nervous regulation of its activity);
- excess type - is caused by functional insufficiency of internal and external sphincters of the bladder;
- functional type - in the absence of the usual conditions for urination or for physical, mental disorders in the patient.
Reduction of the contractility of the inner and outer sphincters of the bladder, the longitudinal musculature of the posterior urethra, impoverishment of the bladder venous plexus by the vessels weaken the function of the bladder closure, and changes in the vesicoureteral angle (due to disruption of the urethral ligament apparatus) facilitates the excretion of urine from the bladder and also promotes development of incontinence.
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Age-related changes in the endocrine system
When aging changes the production of hormones, the binding of hormones to proteins, the reception of target cells.
In the hypothalamus, lipofuscin accumulates in nuclear cells, the neurosecretory response to reflex (skin-pain) or nerve afferent stimuli weakens, and the response to humoral stimuli (for example, adrenaline) increases. In the pituitary gland production of "triple" hormones of the anterior lobe - thyreotropic (TSH), somatotropic (STH), adrenocorticotropic (ACTH) and others. In general, the age-related changes in the various links of the hypothalamic-pituitary system are uneven.
The aging process in the thymus begins at puberty, and its cortical substance almost completely disappears to old age, which leads to a significant reduction in the capacity of the immune system.
The connective tissue stroma increases in the thyroid gland, the number of follicles decreases and the thyroid gland fixes iodine, which leads to a decrease in the blood levels of thyroxine and triiodothyronine (up to 25-40% after 60 years) - signs of hypothyroidism develop.
In the adrenal glands, structural reorganization of the cortex takes place after 30 years, the glandular (glucocorticoids) and mesh (produces sex hormones) zones increase, in the 50-70 years the adrenal cortex is represented mainly by the beam zone, while the total production of adrenal hormones, their adaptive reserves decreases.
The blood supply to the pancreas worsens, the number of cells in the islets of Langerhans decreases and the biological activity of insulin produced in them. With aging, the blood sugar level rises.
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Age changes in the sex glands
From 18 to 80 years in the testes decreases the activity of spermatogenesis; in the blood plasma, the testosterone content gradually decreases and the level of testicular estrogens increases. The weight of the testicles decreases, however, libido and sexual potency can occur in men up to 80-90 years. In the prostate gland, connective tissue and muscle elements predominate over the secretory ones, the mass and tendency to hypertrophy increase. In the ovaries, atrophy of the follicles occurs, they wrinkle, gradually turning into dense fibrous plates (from the age of 30 the secretion of estrogen decreases, and after 50 years - the secretion of gonadotropins).
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Age-related skin changes
Age changes in the skin begin after 20 years, grows after 40 years, becomes pronounced to 60-75 years and is especially evident in 75-80 years:
- characteristic formation of wrinkles, furrows, folds (starting with open parts of the body - face, neck, hands);
- gray hair, hair loss, increased hair growth in the eyebrow, external auditory meatus;
- in the epidermis, the growth is reduced and the stratum corneum increases;
- Collagen fibers become coarser, locally homogenized;
- elastic fibrils thicken, shorten, their lysis increases;
- the connective-tissue papillae are smoothed, the subcutaneous-fat layer decreases, pigment spots appear;
- through the thin, as a whole, the skin radiates through the skin;
- decreases the amount of sebaceous and sweat glands,
- the skin becomes dry;
- the lumen of the vessels of the dermis considerably narrows, their walls are sclerosed;
- in general, the skin becomes thinner, its protective properties are significantly impaired;
- the threshold of tactile sensitivity increases.
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Age-related changes in the hematopoiesis system
Age-related changes in the red bone marrow:
- the medullar space is gradually filled with fat tissue;
- the activity of the erythropoietic (hematopoietic) tissue decreases, but the erythrocyte maturation persists;
- maturation of granulocytes does not change significantly (neutrophilocytopoiesis decreases slightly);
- there is lymphoid hyperplasia;
- the number of megakaryocytes decreases, but they function more slowly and economically.
Age changes in the thymus gland (thymus):
- from the age of 16-20 the thymus undergoes reverse development, which is accompanied by a decrease in the number of lymphocytes, especially in the cortical matter of the lobules, the appearance of lipid inclusions in connective tissue cells and the growth of adipose tissue;
- significantly cortical substance is atrophied;
- often hematothymic barrier is broken.
Age changes in the spleen:
- thickened reticular fibers, collagen fibers are formed;
- gradually red and white pulp atrophy, the proliferation of T-lymphocytes weakens;
- the number of lymphoid nodules and the size of their germinal centers decrease;
- more accumulated iron-containing enzyme, which reflects the death of red blood cells.
Age-related changes in lymph nodes:
- thickening of connective tissue capsule and trabecula, atrophy of myocytes and decrease in motor function of the lymph node;
- signs of fatty degeneration of the superficial lymph nodes, leading to lymphatic obstruction;
- the amount of lymphoblasts in the cortex decreases, the number of macrophages, mast cells and eosinophils increases;
- stabilization of aging in the lymph nodes occurs at the age of 60-75 years.
Age changes in blood:
- increases the lifespan of erythrocytes up to 154 days;
- the number of erythrocytes in longevities decreases insignificantly;
- the area of erythrocytes gradually decreases and the level of enzymes and hemoglobin in the cytoplasm of these cells decreases;
- the number of leukocytes and their activity decreases;
- in persons older than 70 years, the number of platelets decreases and their involution accelerates;
- in the blood plasma the content of fibrinogen, y-globulin increases and the level of albumins decreases;
- the rheological properties of blood change, the ESR is increased to 40 mm per hour.
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Age-related changes in the musculoskeletal system
Age changes in muscles:
- reduction in the number of muscle fibers and their diameter;
- increase in fatty inclusions and lipofuscin in muscle cells;
- decrease in the number of functioning capillaries and neurons per muscle unit;
- decreased ATP-ase activity of muscles.
Age changes in the bones:
- osteoporosis as a result of protein deficiency and a decrease in the content of minerals in tissues;
- an increase in the epiphyses of the tubular bones, the formation of bony growths (hyperostosis and exosteosis), a thickening of the preserved bone beams;
- kyphosis of the thoracic region and lordosis of the lumbar spine increase;
- the arch of the foot is flattened, the growth decreases;
Age changes in the joints:
- calcification of tendons and articular bags;
- progressive degeneration of the articular cartilage, narrowing of the joint gap, reduction of the intra-articular fluid;
- destructive age changes in intervertebral discs and adjacent tissues (osteochondrosis develops).
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Age-related changes in the organ of vision
- Decrease in the elasticity of the lens and the zinn ligament, weakening of the ciliary muscle, resulting in a disruption of accommodation; Increase the size of the lens and change its shape;
- senile far-sightedness - presbyopia (on average, 1 D every decade, starting at age 40); difficulty in circulating the intraocular fluid, high risk of glaucoma (increased intraocular pressure); limiting visual fields, reducing adaptation to darkness;
- weakening the tone of the circular muscle of the eye, the pumping function of the lacrimal ducts - a violation of the timeliness of the outflow of tears.
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Age-related changes in the organ of hearing
- Hyperostosis and narrowing of the inner auditory orifice;
- calcification of the articulations of the auditory ossicles and fibers of the basal membrane of the cochlea;
- a decrease in the amplitude of the movements of the tympanic membrane;
- violation of patency of the auditory tube; increasing the threshold of perception of sounds, especially high frequency - the development of presbybicusis;
- weakening the function of the vestibular apparatus, reducing the sense of balance - dizziness, falling.
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Age-related changes in the nervous system
- Gradually decreases the number of nerve cells: from 10-20% in 60 years old, to 50% in the elderly;
- dystrophic age-related changes in cells of the nervous tissue grow: neurons accumulate lipofuscin (the product of oxidation of unsaturated fatty acids), develops senile amyloidosis of the brain (the appearance in cells of a special protein - amyloid);
- focal demyelination of nerve fibers develops, which leads to a slowing down of excitation along the nerve fiber and an increase in the reflex time;
- in the different parts of the nervous system, the exchange of neurotransmitters (dopamine, serotonin and norepinephrine) is disrupted - this increases the risk of depression and Parkinson's disease;
- In the final brain, there are atrophic age-related changes in the gyri, furrows widen (this is most pronounced in the frontal and temporal lobes);
- The inhibitory effects of the cerebral cortex on the activity of the subcortical structures are relaxed;
- Slowly the old conditioned reflexes fade away and new ones are difficult to develop;
The memory decreases, mainly short-term, which, along with other processes in organs and systems, reduces the ability to learn.
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