Brief post-embryonic period. Postembryonic development

22.11.2019 -

Postembryonic development is accompanied by growth. However, it can be limited to a certain period or last throughout life.

There are 2 main types of postembryonic development:

direct development
development with transformation or metamorphosis (indirect development)

Direct postembryonic development- this is when a born organism differs from an adult in smaller sizes and underdevelopment of organs. In the case of direct development, the young individual differs little from the adult organism and leads the same way of life as adults. This type of development is characteristic, for example, of terrestrial vertebrates.

During development with metamorphosis a larva appears from the egg, sometimes outwardly completely different and even differing in a number of anatomical features from adult. Often the larva leads a different way of life compared to adult organisms (for example, butterflies and their caterpillar larvae). It feeds, grows, and at a certain stage turns into an adult, and this process is accompanied by very deep morphological and physiological transformations. In most cases, organisms are unable to reproduce in the larval stage, but there are a few exceptions. For example, axolotls - larvae of tailed amphibians - are able to reproduce, while further metamorphosis may not occur at all. The ability of organisms to reproduce in the larval stage is called neoteny.

There are also 3 periods of post-embryonic development: - juvenile (until the end of maturation) - pubertal (takes most of life) - aging (until death)

Development- biological: 1) an irreversible, naturally directed process of closely interconnected quantitative (growth, increase in the number of cells, etc.) and qualitative (differentiation, maturation, aging, etc.) changes in an individual and an individual from the moment ... ... Concepts of modern natural science. Glossary of basic terms

Ontogeny (from the Greek οντογένεση: ον being and γένεση origin, birth) is the individual development of an organism from fertilization to death. In multicellular animals, as part of ontogenesis, it is customary to distinguish between phases of the embryonic (under cover ... ... Wikipedia

EMBRYO DEVELOPMENT- (embryonic development, embryogenesis, embryogeny) covers the initial stages of development of a new individual from an egg, proceeding under the protection of egg or embryonic membranes, up to its hatching from the membranes or birth. The duration of the embryonic ... Big Medical Encyclopedia

Same as post-embryonic development... Great Soviet Encyclopedia

- (from the Greek οντογένεση: ον being and γένεση origin, birth) the individual development of the organism from fertilization (during sexual reproduction) or from the moment of separation from the mother individual (during asexual reproduction) to death ... Wikipedia

Books

Fundamentals of cestodology. Volume 14. Aploparaxides of wild and domestic birds, Bondarenko Svetdana Kirillovna, Kontrimavichus Vytautas Leonovich. The monograph summarizes the results of studies of cestodes of the family Aploparaksidae Mayhew, (Cyclophyllidea). They are based on collections from Chukotka, Kolyma, Taimyr, the lower reaches of the Yenisei and Ob, ...

Basic concepts and key terms: Postembryonic development. Age periods of a person. reproductive health. Remember! What is development?

Think!

Why does a person change in the process of development, if the hereditary information received from parents is the same in each of the age periods?

What are the features of postembryonic development?

After the birth of a child, its postembryonic development begins, continuing until the end of life. With the onset of puberty in postembryogenesis, three periods are distinguished: pre-reproductive, reproductive and post-reproductive.

The pre-reproductive period is the period of the body's life from birth to the onset of puberty. For girls, this period lasts from birth to 16 years, for men - up to 18 years. It is characterized by the continuation of the development of organs and an increase in the mass and growth of the body. enhanced growth the child is observed at the age of 1-3 years, at the age of 5-7 years and in adolescence. A person up to reproductive period differs in rather bigger duration as there is a physiological and mental development.

The reproductive period is the period of puberty of the body, characterized by the ability of a person to reproduce. In this interval, the human body functions as a stable self-regulating system. The period is characterized by the balance of the processes of formation and death of cells and the preservation of body mass and size. During this period, the mass increases, mainly due to adipose tissue, although with sports training it can increase due to muscle mass.

The post-reproductive period is a period characterized by the loss of the body's ability to reproduce. In the human body, the water content, the intensity of metabolism decrease, vital functions are weakened, a decrease in body weight and size is observed. At this stage, aging occurs. Human aging is a process of natural occurrence age-related changes, which gradually lead to a reduction in the adaptive capabilities of the body. The science of the laws of aging is gerontology. Signs of aging appear at all levels of the organization of a living organism. So, in cells, the activity of enzymes decreases, the processes of self-healing of proteins are disrupted, nucleic acids. Loss of CNS neurons plays a special role in aging.

So, POST-EMBRIONAL DEVELOPMENT is the development from birth to death of an organism, the main events of which are puberty, growth and aging.

What are age periods postembryonic human development?

Age periods are periods of a person's life that differ in the characteristics of growth and development. In accordance with age characteristics development life cycle man is divided into periods.

Neonatal period (first 10 days). The newborn has a disproportionate physique, bones of the skull and pelvic bones not fused, there are fontanelles in the skull, the spine without bends. The respiratory organs, the pulmonary circulation, the mechanisms of thermoregulation begin to function, the the immune system food reflexes appear.

Breast age (up to 1 year). The child's height increases - by an average of 23-25 cm, the curves of the spine are formed, milk teeth appear. Muscles are formed and there is a need to walk, food conditioned reflexes.

Early childhood - the period of toddler age (1-3 years). The fontanelles overgrow in the child, the proportions of the body change, growth slows down (8-11 cm per year), the brain develops, milk teeth finish forming. There is a gradual transition to a common table, speech, thinking, emotions are rapidly developing.

The first childhood is the period preschool age(3-7 years). In preschoolers, milk teeth are replaced with permanent ones, children grow by 5-7 cm per year. In movements, stable consistency is manifested, speech is associated with thinking, conditioned reflexes of writing are formed, fantasy develops, and play is the leading activity.

The second childhood is the junior school age (7-10 years). There is a slowdown in growth rates, the development of the musculoskeletal system, the secretion of sex hormones contributes to the appearance of secondary sexual characteristics. The leading activity is learning, which determines the development of mental abilities.

Adolescence is the period of middle school age (11-14 years). During this difficult period, there is a rapid development of all systems, intensive puberty, secondary sexual characteristics are formed. The development of abstract thinking, emotions is observed, and mental imbalance is manifested.

Youth period - the period of senior school age (15-17 years). Growth, body formation and puberty are completed.

Mature age occurs at the age of 21. The first period of adulthood (up to 35 years) is the most productive period in a person's life. The second period of adulthood (from 35 to 60 years) is the period of a person's realization of his capabilities.

Old age begins at 61 for men and 56 for women.

Senile age begins at 75 years. People aged 100 years or more are long-livers.

So, the postembryonic development of a person has a conditional periodization based on biological and social characteristics.

How adverse factors affect human reproductive health?

Reproductive health is a state of well-being of functions and processes reproductive system, as well as sexual relations at all stages of life. In other words, it is the ability of people to conceive and have children, the opportunity sexual relations without the threat of sexually transmitted diseases, the safety of pregnancy and childbirth, the survival of the child, the well-being of the mother and the possibility of planning subsequent pregnancies.

Many factors affect human reproductive health, but the most common causes of violations are abortion, diseases of the genital organs, bad habits, infectious diseases etc.

Abortion causes hormonal stress, leads to various violations physical and psychological state. It is no secret that abortion can lead to infertility in the future. The early onset of sexual activity and, as a result, abortions, in many women are the causes of not only infertility, but also the development of many diseases of the body.

Sexually transmitted infections (STIs) are a common cause of genital diseases. Diseases such as syphilis, gonorrhea, trichomoniasis, chlamydia, genital herpes destroy the genitals, lead to infertility and infection of the unborn child. Diseases such as AIDS, hepatitis B and C can be sexually transmitted and threaten not only the reproductive health of a person, but also his life.

Alcoholism, smoking and drug use lead to infertility, miscarriage and the birth of seriously ill children. The presence of these bad habits contributes to the development of impotence, causes a delay in intrauterine development of the fetus, the formation of severe malformations, the occurrence of drug addiction in a newborn, mental retardation and etc.

Planning and careful preparation of future parents for pregnancy, maintaining a healthy lifestyle, giving up bad habits contribute to the normal course of pregnancy and childbirth, the birth of healthy children.

So, reproductive health is an important component general health every individual, every family and society as a whole.

ACTIVITY

Learning to know

Independent work with the table

Apply the acquired knowledge and justify the main recommendations for maintaining the reproductive health of women and men.

	Rationale

If sexually transmitted infections are detected, treatment should begin as soon as possible.
Avoid hypothermia of the lower body, strong blows in the genital areas
Lead an active lifestyle
Organize reasonable balanced diet with the necessary content of vitamins and bioelements
Avoid unwanted pregnancies and abortions, including by using modern means contraception
The optimal age for the birth of a child is 20-35 years

Biology + Anatomy

In the skull of a newborn there are fontanelles - areas between the bones of the skull, protected by soft connective tissue. A baby is born with six fontanelles: four of them close in the first days of life, the fifth - approximately in the second month, and the sixth - the largest - closes in the period from three months up to two years. These are anterior (1) and posterior (2), two wedge-shaped (3) and two mastoid (4). Apply the knowledge of the skull and describe the location of the fontanelles, determine their biological significance.

Biology + Medicine

Prostatitis is the most common male disease, with which at least half of the men on the planet are familiar. About prevalence various kinds prostatitis is evidenced by a formula quite well-known in medical circles, according to which 30% of men over 30 years old, 40% of men over 40 years old, 50% over 50 years old, and so on suffer from this disease. In addition, in recent years, prostatitis has become much “younger”, and the symptoms of prostatitis are increasingly observed in very young men, especially in major cities. Try to explain why. What role does the prostate play in male reproductive health?

RESULT

	Questions for self-control
	1. What is postembryonic development? 2. Name three main stages of human postembryonic development. 3. What are age periods? 4. Why are age periods of a person distinguished? 5. What is human reproductive health? 6. Name the environmental factors unfavorable for reproductive health.
	7. Name the features of postembryonic development. 8. Name the age periods of human postembryogenesis. 9. How do adverse factors affect human reproductive health?

Generalization of the topic 11.

REPRODUCTION AND HUMAN DEVELOPMENT

REPRODUCTION, or REPRODUCTION, -

the ability of organisms to reproduce their own kind, which ensures the existence of the species in time.

In man sexual reproduction occurs with the participation of gametes, which, during fertilization, form a zygote with hereditary information of two individuals of different sexes. The new organism carries the hereditary information of both parents. This contributes to hereditary variability and creates favorable conditions for the existence and development of the species Homo sapiens.

In humans, sexual reproduction with dioecious and sexual dimorphism and internal fertilization
male reproductive system		female reproductive system
External genitalia: scrotum, penis Internal genital organs: testicles, epididymis, vas deferens, seminal vesicles, ejaculatory duct Prostate		External genitalia: labia and clitoris Internal reproductive organs: ovaries, fallopian tubes, uterus, vagina
testicles produce estrogen		The ovaries produce estrogen
Spermatogenesis occurs in the testicles, provides the formation of spermatozoons		Oogenesis occurs in the ovaries to produce eggs
Internal fertilization occurs at the top fallopian tubes. The main stages of fertilization: 1) internal insemination; 2) meeting of gametes and activation of the egg; 3) penetration of the spermatozoon into the egg; 4) fusion of nuclei; 5) activation of the zygote to division.

ONTOGENESIS, or INDIVIDUAL DEVELOPMENT -

the period of an organism's existence from zygote to death.

For a person as a biological species, an increase in the duration of the intrauterine period, a slowdown in puberty, the appearance of a transitional period (menopause) between periods of puberty and old age are characteristic.

This is textbook material.

In this article, we will answer the question of what postembryonic development is, consider its main stages and their features.

Definition 1

Postembryonic or postnatal period(also called postembryogenesis) is the period of human development from birth to death.

The main stages of postembryonic development

Postembryonic period human development can be divided into three main stages:

juvenile (pre-reproductive) period, which ends with the onset of puberty;
mature (reproductive) - the period of a person's life in a state of maturity;
the period of old age (post-reproductive), ending with the death of a person.

This classification is conditional, since the state different people the same age can differ significantly, so the classification of ages is also used:

chronological or calendar;
biological.

The peculiarity of the biological age is that it may not correspond to the calendar (indicated in the passport). Biological age is determined by the structural, functional, metabolic characteristics of a particular person (his body), as well as his adaptive abilities.

Juvenile period in human development

Definition 2

Juvenile period- this is the period starting from the moment of birth and ending in women up to 21 years, in men - up to 22 years.

The juvenile period, in turn, is divided into several stages:

The neonatal period, which lasts the first month of a child's life. The baby continues to take the position of the embryo, characteristic of its intrauterine development. Most of the time, a small person at this stage of growth is in a state of sleep.
Breast period. An infant is called a child aged from one month to a year. This stage is characterized by active changes in propulsion system. By the end of the first month, the child is just trying to straighten his legs; at 1.5 months, the baby is able to raise and hold his head; 6 months is the time when most children learn how to sit; and already by the first year of life, many of them take their first steps. At the same time, it should be noted that the age moment of the appearance of a particular skill is a purely individual process; we have given only averaged boundaries.

IN breast period The mind of the child develops rapidly. In the second month of life, it is already possible to observe the first smile of a child; at 4 months, the baby becomes able to grab objects and explore them, taking them in his mouth, to distinguish between people; after the onset of 6 months, understanding of individual words and phrases comes. high physical activity the first year of life accelerates metabolic processes and normalize work nervous system. In order for the child to develop correctly during this period, three conditions must be observed: gradualness, repetition and systematicity. At the same time, the organization of a clear regime makes it possible to develop conditioned reflexes in the baby.

Early childhood is the period from one to three years of age. Early childhood is the most important stage in the physical and mental development child, characterized by active growth, familiarization with adult food, laying the basic personality traits, such as independence, the desire for self-respect, self-expression. At this age, a small person makes the first attempts to determine his place in this world, gets the skill of living the entire spectrum of feelings available to a person. No wonder the notorious crisis of three years in strength and structure mental changes is considered almost more difficult than the teenage crisis. At this stage, mastering new skills occurs in the process of imitating adults.
The preschool period is the period of human development between the ages of three and seven. The child actively learns the world shows curiosity. This is a period of active development of the brain, the formation of the so-called inner speech. At this stage, the game is the most important tool for the formation of skills.
School age is the period of growing up from 7 to 17 years. The school period can be divided into stages:

early (7 - 11 years);
medium (boys: 11 - 15 years old; girls: 11 - 14 years old);
senior (15 - 17 years).

On the early stage children master written language, gain the skill of collectivism, being in society, learn about the world around them, and gain the first experience of interactions. Adolescence is characterized by a rapid pace of physical and sexual development.

Adolescence is the stage of development between the ages of 17 and 21. On the this stage we have a formed personality, which in practical life begins to implement the acquired skills.

Mature period in human development

Definition 3

mature period postnatal development begins at the age of 21 - 22 years (in women and men, respectively).

This period is divided into two stages:

up to 35 years;
from 36 to 55 for women and 60 for men.

At the first stage, there are some changes in physiological reactions, metabolism, which are the precursors of involution. After 45 years, significant changes in endocrine functions occur in the human body. After 50 years, processes are launched that are the beginning of the aging period.

human aging period

Remark 1

The aging period occurs in women after 55 years; in men - after 60.

Modern classification divides people in the aging period into groups:

60 - 76 years old - elderly people;
75 - 89 years old - old;
over 90 years old - centenarians.

Definition 4

Aging is a natural stage of development, characteristic not only of man, but also of any other living organism. This period is studied by gerontology, which establishes the patterns of aging and forms recommendations for extending life.

Take place the following signs aging:

graying of hair (begins after 30 years, and sometimes earlier, and constantly progresses);
apparently changing the texture of the skin, its appearance;
posture changes;
there is a decrease in muscle strength;
tooth loss;
there is a decrease in internal organs;
blood vessels become less elastic, and as a result, blood pressure changes;
the adaptive and regenerative abilities of the body, immunity decrease and the process of heat generation slows down;
the quality of vision and hearing deteriorates;
there is a deterioration in memory, a reduction in reaction time, a decrease in efficiency.

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Lecture 14 Topic: Fundamentals of ontogenesis

(postembryonic development)

Lecture plan

1. Periodization of postnatal ontogenesis.

2. Growth: patterns and regulation of growth.

3. Constitution and habitus.

4. Aging and old age. Theories of aging.

5. Death is clinical and biological.

6. The concept of resuscitation and euthanasia.

Postembryonic (postnatal) period - this is the period from the moment of birth or exit from the egg membranes until death. Morphogenesis ends, puberty sets in, reproduction takes place, and the final stage of ontogenesis is aging and death.

Types of ontogeny

direct development	indirect development (with metamorphosis)

a) laying eggs with a large	a) incomplete metamorphosis
the amount of yolk (birds)		- adult
	(intestinal worms)

b) intrauterine (mammals)		metamorphosis

		adult
	(butterflies, two-winged insects)

Periodization of postnatal ontogenesis in humans.

Neonatal period(1-10 days): a difficult period of restructuring of the whole organism, adaptation to new conditions of existence.

Breast period (11 days - 12 months): feeding the child with mother's milk; intensive growth.

early childhood period(1-3 years): the child learns to walk and talk, gets acquainted with the outside world.

First period of childhood(4-6 years old): the child is interested in everything and strives to understand everything, masters elementary labor skills.

Second period of childhood(girls 7-11 years old, boys 7-12 years old): growth slows down, the muscular system develops intensively.

Teenage years(girls 12-15 years old, boys 13-16 years old): puberty begins and growth intensity increases.

adolescence(girls 16-20 years old, boys 17-21 years old): puberty, growth and physical development ends.

Average age, I period(women 21-35 years old, men 22-35 years old):

optimal period for childbearing.

Middle age, II period(women 36-55 years old, men 36-60 years old):

the period of the most active professional activity; after 35 years, the first signs of aging begin to appear - some biochemical reactions and physiological functions change.

Old age (women 56-75 years old, men 61-75 years old): aging processes continue to develop, although most people retain their professional ability to work.

Senile age(76-90 years old): senile changes are noticeably expressed; some people at this age retain the ability to creative work.

Age of centenarians(over 90 years): women live to this age more often.

In postnatal there are critical periods:

1. Neonatal period(the first days after birth) - there is a restructuring of all organ systems for a new habitat.

2. puberty(12-16 years) - hormonal restructuring, the entry of sex hormones into the blood and the formation of secondary sexual characteristics.

3. period of puberty(on average, about 50 years) - the extinction of the functions of the gonads and endocrine glands).

In animals and humans, there are three periods of postnatal ontogenesis: 1) pre-reproductive (juvenile); 2) reproductive (mature);

(crustaceans, fish, reptiles) and limited (certain) - ceases to certain age(insects, birds, mammals). The process of human growth proceeds unevenly; alternating periods rapid growth and periods of slow growth.

Growth patterns

The greatest intensity of human growth was noted in the first year of life - an increase of 25 cm. In the second year of life - by 10-11 cm, in the third - by 8 cm. At the age of 4 to 7 years, an increase in height - by 5-7 cm Every year. In junior school age- 4-5 cm per year, during puberty, the growth rate increases to 7-8 cm per year. After this period, human growth slows down and then increases by 1-2 until the age of 20-25.


The main types of tissue and organ growth:
			lymphoid
	lymph nodes, intestinal lymphoid tissue,


	spleen,		tonsils;		maximum
	increase in their weight up to 11-12 years.
	increase in their weight up to 11-12 years.

			cerebral		head
			cerebral		head
		brain, eyes,			develop
		brain, eyes,			develop


	birth and up to 10-12 years.
	birth and up to 10-12 years.			whole body,
		– general type:		whole body,

4 6 8 10 12 14 16 18 20		respiratory system,

maximum growth in the first year of life and in

puberty; 4 - reproductive type: various parts of the reproductive system -

rapid growth during puberty.

growth regulation

growth hormone produced from the birth of a child to 13-16 years. With a decrease in the function of the gland, pituitary dwarfs develop, with its increase, gigantism develops - a person's height reaches 2 meters or more. The release of the hormone in adulthood leads to acromegaly - an increase in the size of the bones of the hand, foot

and faces. Thyroxine increases energy metabolism in the body. A decrease in the function of the gland leads to growth retardation, a violation of the proportions of the body, a delay in sexual development, and a mental disorder. Sex hormones affect all metabolic processes.

Environmental factors have a significant impact on growth. For the normal growth of the child, a balanced diet, the inclusion of vitamins and trace elements in it, is necessary. In the synthesis of vitamin D (calciferol) important role sunlight plays.

Over the past few decades, there has been an acceleration in the physical

And physiological development of children, called acceleration. It manifests itself already at the stage of intrauterine development - an increase in the body length of newborns by 0.5 - 1.0 cm, body weight - by 50-100 g, the timing of teething changes. Height in adults over the past 100 years has increased by an average of 8 cm. Cause of acceleration consider the following factors: interracial marriages (increased heterozygosity), urbanization, increased radiation background, change magnetic field Land and a number of social factors.

Person's age

Biological - for how many years Chronological- number of years,

Biological and chronological age do not always coincide.

Criteria for determining biological age:

- skeletal maturity: ossification of various parts of the skeleton occurs

in different ages;

- dental maturity: the appearance of milk teeth and their replacement by permanent ones occurs at a certain age;

- time of appearance and degree of development of secondary sexual characteristics.human constitution are genetically determined

features of morphology, physiology and behavior.

In 1927, M.V. Chernorutsky proposed a classification according to which three main constitutional types are distinguished.

Ectomorphic type (asthenics). They have a narrow chest, low position of the diaphragm, elongated lungs, relatively short intestines with low absorption capacity, thin bones And long limbs, a slight layer of body fat. Asthenics are characterized by: increased excitability, a tendency to neurosis, hypotension, peptic ulcer, tuberculosis.

Mesomorphic type (normostenics): have a proportional physique, moderate development of subcutaneous adipose tissue. People of this type are energetic, mobile, prone to neuralgia, atherosclerosis, diseases of the upper respiratory tract.

Type endomorphic (hypersthenics) are characterized by a wide chest, a high position of the diaphragm, a voluminous stomach and a long intestine with a high absorption capacity, a significant deposition of fat. Heart is relative large sizes, high cholesterol in the blood, uric acid, erythrocytes and hemoglobin. Hypersthenics are dominated by assimilation processes, they are prone to atherosclerosis, obesity, diabetes, hypertension, diseases of the kidneys and gallbladder. People of this type are balanced, calm, sociable.

Most people are in an intermediate position according to the types of constitution.

Features of morphology, physiology, behavior in a certain period of time - this is habitus. Habitus reflects the well-being of a person

and current state of health. It includes: body features, posture, gait, color skin, facial expression, correspondence of biological and chronological age.

Aging is a general biological regularity inherent in all living organisms. Old age - The final stage ontogeny. The science of old age is called gerontology. It studies the patterns of aging of various organ and tissue systems. Gerontology includes sections of gerontohygiene and gerontopsychology.

Geriatrics - the science of human disease old age; studies the features of their development, course, treatment and prevention.

The aging process covers all levels - molecular, subcellular, cellular, tissue, organ and organism. The result of this process is a decrease in the viability of an individual, a weakening of the mechanisms of homeostasis and adaptation. The biological meaning of aging is the inevitability of death.

Signs of aging in organs and organ systems.

1. Cardiovascular system. Change in the elasticity of the walls of blood vessels; growth in the heart and in the walls of the vessels of the connective tissue in place of the muscle; impaired blood supply to tissues and organs. Decreased function of the hematopoietic organs.

2. Respiratory system. Destruction of the interalveolar septa and reduction of the respiratory surface of the lungs; decrease in their vital capacity; proliferation of connective tissue.

3. Digestive system. Loss of teeth, decreased functions of the digestive glands, impaired motor (motor) function of the intestine.

4. Urinary system. The death of part of the nephrons, a decrease in the intensity of kidney filtration.

5. Muscles and skeleton. Atrophy skeletal muscle, decrease in bone strength, the predominance of minerals in their composition.

6. Nervous system. The death of neurons, dysregulation of organ functions, a decrease in the speed of impulse conduction, weakening of memory. Decreased functions of all sense organs.

7. Weakening of the mechanisms of humoral and cellular immunity. External manifestations signs of aging: changing posture, shape

body, gait; gray hair appears, skin elasticity is lost (the appearance of wrinkles), vision and hearing are weakened.

Gerontology offers more than 300 aging hypotheses. The most common of these are as follows.

1. Energy (M.Rubner, 1908): the body of each species has a certain energy fund. It is consumed during life and the body dies.

2. Intoxication(I. Mechnikov, 1903): self-poisoning of the body

in as a result of the accumulation in the human large intestine of products of nitrogen metabolism and putrefaction.

3. connective tissue(A. Bogomolets, 1922): since connective tissue is a regulator of cell and tissue trophism, changes in it disrupt intertissue interactions and lead to aging.

4. Overstrain of the central nervous system(I. Pavlov, 1912,

G. Selye, 1936): nervous turmoil and long nervous tension cause premature aging.

5. Changes in the colloidal properties of the cytoplasm of cells(V. Ruzhichka,

M. Marinescu, 1922): the altered cytoplasm retains water poorly, colloids from hydrophilic become hydrophobic, colloidal particles become larger and their biological properties change.

6. Programmed number of cell mitoses(A. Hayflick, 1965):

different species have different numbers cell divisions– with a longer life span, there are more of them (human embryonic fibroblasts give about 50 generations, in mice and chickens, about 15 generations).

7. Genetic: accumulation of mutations; decrease in intensity and disruption of the processes of transcription, translation and repair; disruption of protein self-renewal.

significant impact on the aging process social factors, conditions and lifestyle various diseases. Aging and human life expectancy also depend on the environmental situation.

science that studies healthy lifestyle human life and the conditions for increasing its duration, is called valeology.

Theoretically, the possible age of a person is 150-200 years, the maximum recorded is 115-120 years. Average life expectancy: men 67-74, women 74-79 years. In some countries, the average life expectancy is 35-40 years.

The aging of the organism ends with death. Death ensures the change of generations. The causes of death may vary. Death is physiological, or natural, occurs as a result of aging. death pathological, or premature, is the result of illness or accident.

Death is clinical occurs as a result of the cessation of vital functions (cardiac and respiratory arrest), but metabolic processes in cells and organs persist.

death biological- cessation of self-renewal processes in cells and tissues, disruption of the course of chemical processes, autolysis and cell decay. In the most sensitive cells of the cerebral cortex, necrotic changes are detected after 5-6 minutes. Increase the onset period clinical death It is possible with the help of general cooling of the body (hypothermia), which slows down metabolic processes and increases resistance to oxygen starvation.

Resuscitation is the possibility of returning a person to life from a state of clinical death (when vital important organs) after 5-6 minutes, while the cells of the cerebral cortex are "alive". Resuscitation methods are used in medicine in any threatening conditions.

In the middle of the twentieth century, a direction appeared in medicine, which was called euthanasia. Euthanasia is health care the death of a hard and terminally ill person at his will or at the request of his relatives. Euthanasia is legal in only a few countries. It requires the resolution of many legal and moral and ethical problems.

Postembryonic development of animals is divided into three periods:

4.1. Postembryonic period of animal development

Period of growth and shaping(pre-reproductive )

This period is characterized by the continuation of organogenesis that began in embryonic life and an increase in body size. By the beginning of this period, all organs have reached the degree of differentiation at which the young animal can exist and develop outside the mother's body or outside the egg membranes. From this moment, the digestive tract, respiratory organs and sensory organs begin to function. The nervous, circulatory and excretory systems begin their function even in the embryo. During the period of growth and shaping, the species and individual characteristics of the organism are finally formed, and the individual reaches the dimensions characteristic of the species. Later, other organs differentiate the reproductive system. When its formation ends, the second stage of postembryonic development begins.

maturity period(reproductive).

During this period of maturity, reproduction occurs. The duration of this period is different for different species of animals. In some species (mayflies, silkworm) it lasts only a few days, in others it lasts for many years.

old age ( post-reproductive).

It is characterized by a decrease in the intensity of metabolism and involution of organs. Aging leads to natural death.

4.2. Postembryonic period of human development

Postembryonic postnatal) period of human development, otherwise called postnatal, is also divided into three periods (Fig. 5):

Juvenile (before puberty);

Mature (adults, sexually mature state);

old age ending in death.

Otherwise, we can say that for a person it is also possible to distinguish pre-reproductive, reproductive and post-reproductive periods of post-embryonic development. It should be borne in mind that any scheme is conditional, since the actual state of two people of the same age can differ significantly. Therefore, the concept of chronological (calendar) and biological age has been introduced. Biological age is determined by the totality of the metabolic, structural, and functional characteristics of the organism, including its adaptive capabilities. It may not correspond to the calendar.

Scheme 5

4.2.1. Juvenile period

According to the accepted periodization, the juvenile period begins after birth and lasts for women up to 21 years, and for men up to 22 years.

The first month of the child is considered neonatal period. The position of the child at this time resembles the position of the fetus in the uterus. Most of the day the baby sleeps, waking up only at the time of feeding. Caring for a child requires strict observance of the time of feeding and preferably with mother's milk, high purity, temperature not lower than 20 ◦ C.

From the first month to a year, the period of time is called chest.

During the first year of life in the child's body, many changes occur in the motor system. At the end of the 1st month, he tries to straighten his legs, at one and a half months he raises and holds his head, at six months he sits, and at the end of the first year of life he tries to take his first steps. During this period, the child's psyche also develops. In the 2nd month, the baby smiles when the mother appears or when bright pictures are shown; by the 4th month he takes toys in his mouth, examining them, begins to distinguish between adults. In the second half of infancy, the child begins to understand many of the phrases of the parents. The active movements of the child at this time contribute to the development of the muscular and skeletal systems, better supply of the body with nutrients and oxygen, i.e. strengthening metabolic processes in the child's body, and most importantly, they normalize the activity of the nervous system. Water and air procedures are necessary during this period for the child.

Three rules must be followed by adults when caring for a child during this period: gradualness, repetition, regularity. A clear regimen of a child's life will develop conditioned reflexes in him, the formation of which makes it possible for the child to develop life skills that ensure high resistance of the organism to the action of adverse factors.

Early childhood- period from one to 3 years. During this period, the child grows intensively, eats the same food as adults, he develops a desire for independence and self-respect. He masters many new movements, imitates adults during the game.

Preschool period- period from 3 to 7 years. During this period, children show great interest in the world around them. Curiosity is so great that this period is also called the stage of questions: where? when? why? why? During this period, the brain continues to grow, inner speech is formed. An external manifestation of this is the child's conversations with himself and with toys. For a child during this period, play is important. It occupies the same place as an adult sports and work. Games develop the child and encourage him to be creative.

School period- period from 7 to 17 years. This period is divided into early(7-11 years old), middle(11-15 years for boys and 11-14 years for girls) and older(15-17 years old). For the early school period, learning is already the main thing. This is a serious, intense work in mastering written language, in educating collectivism, in learning new things about the world around us, in mastering the experience accumulated by many generations of people. All this contributes to a harmonious mental, physical and volitional development schoolchildren.

middle school The period is also called adolescence. In children, a profound restructuring of the activity of all organs and physiological systems takes place. This is due to puberty, with the intensive formation of sex hormones, which entails features of physical and physiological development, both in boys and girls. In adolescence, the development of speech ends, the formation of character and the moral formation of the personality take place.

Adolescents, as well as older schoolchildren, are characterized by accelerated rates of physical and sexual development, called acceleration. For example, in the 20s of our century, the growth of 14-year-old boys reached an average of 145.4 cm, in the 70s, growth reached 162.6 cm, body weight increased by an average of 13.5 kg. The average height and body weight of girls also increased markedly. The causes of acceleration have not yet been fully studied, but it has been found out that the physical development of modern children does not entail their moral and social maturation.

Thus, physiological, psychological and social maturity is distinguished. Physiological maturity is the puberty of the body. The term for achieving physiological maturity is individual. It depends on climatic, hereditary and other factors. Psychological maturity- this is the moral stability of girls and boys, self-control of behavior in the family and society. social maturity- this is a conscious attitude of a person to reality, this is the completion of a person's education, the beginning of labor activity, economic independence, this is, if necessary, the fulfillment of civic duty to the state.