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Age periods of human development. Reproduction

05.11.2020

A. Sebaceous glands

B. Sweat glands

B. Pigment cells

8. Hair on the head protects against the effects of:

A. Low temperatures

B. Radiation

B. Sun rays

9. Nail growth is ensured by continuous cell division:

B. Epidermis

B. Subcutaneous tissue

10. With the expansion of blood vessels of the skin, the heat transfer of the body:

A. Increases

B. Decreases

B. Does not change

11. In extreme heat, the level of perspiration:

A. Increases

B. Decreases

B. Does not change

12. Fever during illness:

A. Reduces the intensity of chemical processes in the body

B. Reduces the activity of the nervous system

B. Increases the activity of leukocytes

13. The strongest hardening factor is:

A. Sunbathing

B. Water treatments

Option 2

The task.Insert the missing word.

1. The outer covering of the body is ... that performs ... and ... functions.

2. Human skin is also involved in the secretion of products ... substances, ... of the body, prevents the loss of ...

3. In the skin, an outer layer is distinguished - ..., an inner layer - ... and a superficial ... layer of dead cells.

4. The skin is formed by ... tissue, contains many ... fibers, blood and ... vessels, nerve endings.

5. The dermis contains ... glands that perform ... a function, and ... glands that soften the skin and prevent it from drying out.

6. Horny formations of the skin are ... and also ... that protect the scalp from the effects of ... rays.

7. When the ambient temperature rises, the vessels of the skin ... and the release of heat ..., this is also facilitated by active ...

Option 3

The task.Give a short answer of one or two sentences.

1. List the main functions of the skin.

2. Name the structural elements of the skin.

3. What determines skin color?

4. How does the skin regulate the body's heat exchange?

5. What is the physiological significance of perspiration?

6. What determines the elasticity and firmness of the skin?

7. Name the protective elements of the skin.

8. What is the significance of a rise in temperature during illness?

Option 4

The task.Give a full detailed answer.

1. On clean skin, up to 85% of bacteria die. How is this happening? What hygienic conclusions follow from this fact?

2. What is fingerprinting?

3. Cooling the feet often causes colds, but cooling the hands does not. How can you explain this?

4. Why is the skin called a blood depot?

5. What is the physiological meaning of the "goose bumps" that appear on the skin during cooling?

6. What types of skin receptors do you know?

REPRODUCTION. HUMAN DEVELOPMENT. AGE PROCESSES

Option 1

The task.Choose one correct answer.

1. Female gametes are called:

A. Follicles

B. Eggs

B. Spermatozoa

2. Human sex cells contain:

A. 46 chromosomes

B. 50 chromosomes

B. 23 chromosomes

3. A female infant develops with the following combination of sex chromosomes:

4. Male gametes are formed:

A. In the prostate gland

B. In the testes

B. In the vas deferens

5. Female gametes are formed:

A. In the fallopian tubes

B. In the womb

B. In the ovaries

6. The period of development of the egg is:

7. Fertilization of the egg occurs:

A. In the fallopian tube

B. In the ovary

B. In the uterus

8. Implantation and development of the embryo occurs:

A. In the fallopian tube

B. In the ovary

B. In the uterus

9. The human zygote contains:

A. 23 chromosomes

B. 46 chromosomes

B. 92 chromosomes

10. Providing the embryo with nutrients and oxygen is carried out using:

A. Placenta

B. Chorion

V. Amnion

11. The gestation period is:

A. 38 weeks

B. 40 weeks

B. 42 weeks

12.With the first cry, the child begins to function actively:

A. Circulatory system

B. Digestive system

B. Respiratory system

13. The child becomes an independent organism:

A. After cutting the umbilical cord

B. After the first breath

B. After the first feeding

5. Fertilization takes place in the uterine ..., the zygote is implanted in the wall ... where the multicellular develops ...

6. Nutrition, respiration and metabolism of the embryo are provided by a special shell - ..., which develops from the villi ..., the connection between the fetus and the mother's body is carried out through ... the cord.

7. The period of intrauterine development of the embryo is called ... and lasts ... weeks, during which the human embryo goes through the stages of development of its ...

8. As a result of involuntary contractions ... the child is born, with the first cry he straightens out ..., and after cutting off ... he becomes an independent creature.

1. What is labor pain?

Labor pains are involuntary contractions of the walls of the uterus, facilitating the passage of the fetus through the birth canal and expulsion of the fetus during childbirth.

2. Remember how respiration is regulated in humans. Knowing this, explain the trigger for the first breath in a newborn baby.

After the umbilical cord ligation, gas exchange through the umbilical vessels carrying oxygen-enriched blood to the fetus stops in a born child. In the blood of the newborn, the amount of oxygen decreases and the carbon dioxide increases, which irritates the chemoreceptors located in the area where the carotid artery leaves. These receptors send excitatory nerve impulses to the respiratory center, which triggers the mechanism of the first breath.

3. What is typical for a newborn baby?

The period of newborn is the first month of a child's life (according to other sources, the first 10 days of life). During this period, the child is weak and helpless. He has developed unconditioned reflexes (sucking, grasping, proboscis) and has not yet formed conditioned ones. All body systems are imperfect, there are no bends of the spine. The need for sleep is up to 21 hours a day. The baby feeds on mother's milk.

4. Why is breast milk better than artificial milk formula?

Mother's milk contains all the substances necessary for the growth and development of the baby in a perfectly balanced form. In addition, breast milk contains antibodies that protect the baby from many infectious diseases in the first months of life, when the baby's immune system is still imperfect and cannot provide it on its own.

5. What period of a person's life is called breast?

The first year of a child's life is called breastfeeding. During this period, the child is actively growing and developing, children sleep a lot, and often eat. They feed on breast milk or artificial mixtures, hence the name of the period. By the end of the breastfeeding period, all the curves of the spine are formed in the child, the child begins to walk, the first milk teeth appear, the child learns to walk and speak, the first conditioned reflexes are formed.

6. When puberty begins in girls; boys?

Puberty in girls begins at 11–12 years old, in boys a little later - at 12–13 years old. At this time, the proportions of the body change, secondary sexual characteristics appear: in girls, the pelvis expands, the hips are rounded, the mammary glands increase, the female pattern of hair growth begins: pubis, armpits; in boys, the growth of the larynx begins, the voice breaks, the skeleton begins to grow according to the male type: a wide shoulder girdle and a slowdown in the growth of the pelvic bones. During this period, children grow up very quickly and gain weight. So, during this period, the growth per year can increase by 20 centimeters! The size of internal organs increases, blood pressure increases.

7. What are the features of development in adolescence?

At the age of 12-16, adolescents have increased secondary sexual characteristics. Girls have menstruation (periodic bleeding from the genital tract): this is a sign that eggs have begun to develop and mature in the ovaries, and the amount of hair on the pubis and armpits is increasing. By the age of 15-16, boys begin to grow hair on the face, body, in the armpits, involuntary discharge of sperm appears - wet dreams - the first sign of puberty in boys (they occur from 1 time in 1.5-2 months to 2-3 times in month). Through pollution, the body is freed from excess semen and sexual tension.

8 What characterizes the period of maturity in a person's life; elderly age; old age?

The structure of the body in adulthood (22-60 years old, according to other sources from 21 to 60 years for men and up to 55 years for women) changes little, this period can also be characterized as a period of relative constancy and stability of body functions at the highest level of its development in its first half (up to 35 years) and a period of slow extinction after 35 years, the period of maturity accounts for the greatest rise in human labor and social activity. In the elderly (61–74 years old) and senile (over 75 years old), there is a restructuring of the body characteristic of these ages: the metabolism slows down, the performance of all organ systems decreases, mental activity slows down, memory is impaired, the skin loses its elasticity, pigment spots of varying degrees appear severity, signs of keratinization, wrinkles first on the earlobes, nose bridge, chin and upper lip, later on the skin of the cheeks, forehead, neck, becoming deeper and more noticeable every year. In an elderly person, with rare exceptions, the figure, posture and gait noticeably change, which is associated with age-related changes in the joints, muscles and skeleton. The gait becomes heavy, slow, and may become "shuffling" in old age. All these processes are more pronounced in obese people.

9. There are cases when children from infancy were isolated from human society and grew up among animals. Getting to people, these children "Mowgli" at the age of 5 years and more have not learned to speak and read well. Explain why.

The lack of human communication in a child leads to abnormalities in the formation of brain cells and a slowdown in communication between its various areas, which are formed at the age of 3 to 6 years. Social isolation in the early years of a person's life leads to severe emotional instability and mental retardation.

10. Why can't an unborn baby in a mother's body cry?

Sounds, including screams, are formed when air passes through the vocal folds, since the fetus does not breathe, then it, accordingly, cannot make sounds.

Physical development of a person is a complex of morphological and functional properties of an organism that determine the shape, size, weight of the body and its structural and mechanical qualities.

Introduction

Growth signs are variable. Physical development of a person is the result of the influence of hereditary factors (genotype) and environmental factors, and for a person - and the entire complex of social conditions (phenotype). With age, the importance of heredity decreases, the leading role passes to individually acquired characteristics.
The physical development of children and adolescents is associated with growth. Each age period - breast, child, adolescence, and youth - is characterized by specific growth characteristics of individual body parts. In each age period, the child's body has a number of characteristic features inherent only in this age. Between the body of a child and an adult, there are not only quantitative differences (body size, weight), but, above all, qualitative ones.
Currently, there is an acceleration of human physical development. This phenomenon is called acceleration.
In my work, I will try to briefly describe each of the main stages of human individual development.

The main stages of individual human development

When studying human development, his individual and age characteristics in anatomy and other disciplines, they are guided by scientifically substantiated data on age periodization. The scheme of the age periodization of human development, taking into account anatomical, physiological, and social factors, was adopted at the VII conference on the problems of age morphology, physiology and biochemistry (1965). It has twelve age periods (Table 1). Table 1

Individual development, or development in ontogeny e, occurs in all periods of life - from conception to death. In human ontogenesis, two periods are distinguished: before birth (intrauterine, prenatal - from the Greek natos - born) and after birth (extrauterine, postnatal).

Prenatal ontogenesis

To understand the individual characteristics of the structure of the human body, it is necessary to get acquainted with the development of the human body in the prenatal period. The fact is that each person has his own individual characteristics of the external appearance and internal structure, the presence of which is determined by two factors. This is heredity, traits inherited from parents, as well as the result of the influence of the external environment in which a person grows, develops, studies, and works.
In the prenatal period, from conception to birth, within 280 days (9 calendar months), the embryo (embryo) is located in the mother's body (from the moment of fertilization to birth). During the first 8 weeks, the main processes of the formation of organs and body parts take place. This period was called embryonic (embryonic), and the body of a future person is an embryo (embryo). From 9 weeks of age, when the main external human features begin to appear, the body is called the fetus, and the period is called fetal (fetal - from the Greek. Fetus - fetus).
The development of a new organism begins with the process of fertilization (the fusion of a sperm and an egg), which usually occurs in the fallopian tube. The merged germ cells form a qualitatively new unicellular embryo - a zygote, which possesses all the properties of both germ cells. From this moment, the development of a new (daughter) organism begins.
The optimal conditions for the interaction of the sperm and the egg are usually created within 12 hours after ovulation. The union of the nucleus of the sperm with the nucleus of the egg leads to the formation of a diploid set of chromosomes, characteristic of humans, in a unicellular organism (zygote) (46). The sex of the unborn child is determined by the combination of chromosomes in the zygote and depends on the sex chromosomes of the father. If an egg is fertilized by a sperm with a sex chromosome X, then in the resulting diploid set of chromosomes, two X chromosomes appear, which are characteristic of the female body. When fertilized with a sperm with a Y sex chromosome, a combination of XY sex chromosomes is formed in the zygote, which is characteristic of the male body.
The first week of development of the embryo is the period of cleavage (division) of the zygote into daughter cells (Fig. 1). Immediately after fertilization, during the first 3-4 days, the zygote divides and simultaneously moves along the fallopian tube towards the uterine cavity. As a result of the division of the zygote, a multicellular vesicle is formed - a blastula with a cavity inside (from the Greek blastula - sprout). The walls of this vesicle are formed by two types of cells: large and small. From the outer layer of small cells, the walls of the bubble are formed - the trophoblast. Subsequently, the trophoblast cells form the outer layer of the membranes of the embryo. Larger dark cells (blastomeres) form a cluster - an embryoblast (embryonic nodule, embryo rudiment), which is located inwardly from the trophoblast. From this cluster of cells (embryoblast), the embryo and the adjacent extraembryonic structures (except for the trophoblast) develop.

Fig. 1. A - fertilization: 1 - sperm; 2 - egg cell; B; C - zygote crushing, G - morublastula: 1 - embryoblast; 2 - trophoblast; D - blastocyst: 1-embryoblast; 2 - trophoblast; 3 - amnion cavity; E - blastocyst: 1-embryoblast; 2-cavity of the amnion; 3 - blastocoel; 4 - embryonic endoderm; 5-amnionytic epithelium - F - I: 1 - ectoderm; 2 - endoderm; 3 - mesoderm.
A small amount of fluid accumulates between the surface layer (trophoblast) and the embryonic nodule. By the end of the 1st week of development (6 - 7th day of pregnancy), the embryo enters the uterus and is introduced (implanted) into its mucous membrane; implantation takes about 40 hours. The surface cells of the embryo, forming a vesicle, - trophoblast (from the Greek trophe - food), secrete an enzyme that loosens the surface layer of the uterine mucosa, which is prepared for the embryo to be inserted into it. The forming villi (outgrowths) of the trophoblast come into direct contact with the blood vessels of the mother's body. The numerous villi of the trophoblast increase the surface of its contact with the tissues of the uterine mucosa. The trophoblast turns into the nutrient membrane of the embryo, which is called the villous membrane (chorion). Initially, the chorion has villi on all sides, then these villi are preserved only on the side facing the wall of the uterus. In this place, a new organ develops from the chorion and the adjacent mucous membrane of the uterus - the placenta (children's place). The placenta is the organ that connects the mother's body with the embryo and provides nutrition.
The second week of the embryo's life is the stage when the cells of the embryoblast are divided into two layers (two plates), from which two vesicles are formed (Fig. 2). An ectoblastic (amniotic) vesicle is formed from the outer layer of cells adjacent to the trophoblast. An endoblastic (yolk) vesicle is formed from the inner layer of cells (embryo rudiment, embryoblast). The anlage ("body") of the embryo is located where the amniotic vesicle comes into contact with the yolk vesicle. During this period, the embryo is a two-layer scutellum, consisting of two sheets: the outer embryonic (ectoderm), and the inner embryonic (endoderm).

Fig. 2. The position of the embryo and embryonic membranes at different stages of human development: A - 2-3 weeks; B - 4 weeks: 1 - amnion cavity; 2 - the body of the embryo; 3 - yolk sac; 4 - trofolast; B - 6 weeks; D - fetus 4-5 months: 1 - body of the embryo (fetus); 2 - amnion; 3 - yolk sac; 4 - chorion; 5 - umbilical cord.
The ectoderm is facing the amniotic vesicle, and the endoderm is adjacent to the yolk vesicle. At this stage, the surfaces of the embryo can be determined. The dorsal surface is adjacent to the amniotic vesicle, and the ventral to the yolk vesicle. The trophoblast cavity around the amniotic and yolk vesicles is loosely filled with strands of cells of the extraembryonic mesenchyme. By the end of the 2nd week, the embryo is only 1.5 mm long. During this period, the embryonic scutellum thickens in its posterior (caudal) part. Here, axial organs (chord, neural tube) begin to develop in the future.
The third week of the embryo's life is the period of the formation of a three-layer shield (embryo). The cells of the outer, ectodermal plate of the embryonic flap are displaced to its posterior end. As a result, a cell ridge (primary strip) is formed, elongated in the direction of the longitudinal axis of the embryo. In the head (front) part of the primary stripe, cells grow and multiply faster, as a result of which a small elevation is formed - a primary nodule (Hensen's nodule). The site of the primary nodule indicates the cranial (head end) of the embryo's body.
Rapidly multiplying, the cells of the primary stripe and the primary nodule sprout to the sides between the ectoderm and the endoderm, thus forming the median germ layer - the mesoderm. The cells of the mesoderm, located between the sheets of the scutellum, are called the intra-embryonic mesoderm, and those that have moved out of it are called the extra-embryonic mesoderm.
Part of the mesoderm cells within the primary nodule grows especially actively forward from the head and tail end of the embryo, penetrates between the outer and inner layers and forms a cellular cord - a dorsal string (chord). At the end of the 3rd week of development, active cell growth occurs in the anterior part of the outer germ layer - a neural plate is formed. This plate soon bends, forming a longitudinal groove - a nerve groove. The edges of the groove thicken, approach and grow together with each other, closing the neural groove into the neural tube. In the future, the entire nervous system develops from the neural tube. The ectoderm closes over the formed neural tube and loses its connection with it.
In the same period, from the back of the endodermal plate of the embryonic flap, a finger-like outgrowth - allantois, which does not perform certain functions in humans, penetrates into the extraembryonic mesenchyme (the so-called amniotic leg). In the course of allantois from the embryo to the chorionic villi, blood umbilical (placental) vessels grow. A cord containing blood vessels that connects the embryo to the extraembryonic membranes (placenta) forms the abdominal stalk.
Thus, by the end of the 3rd week of development, the human embryo has the appearance of a three-layer plate, or a three-layer shield. In the area of \u200b\u200bthe outer germ layer, the neural tube is visible, and deeper - the dorsal string, i.e. the axial organs of the human embryo appear. By the end of the third week of development, the length of the embryo is 2-3 mm.
The fourth week of life - the embryo, which looks like a three-layer shield, begins to bend in the transverse and longitudinal directions. The embryonic scutellum becomes convex, and its edges are delimited from the amnion surrounding the embryo by a deep groove - the trunk fold. The body of the embryo from a flat shield turns into a volumetric one, the ectoderm covers the body of the embryo from all sides.
From the ectoderm, the nervous system, the epidermis of the skin and its derivatives, the epithelial lining of the oral cavity, the anal rectum, and the vagina are subsequently formed. The mesoderm gives rise to internal organs (except for endoderm derivatives), the cardiovascular system, organs of the musculoskeletal system (bones, joints, muscles), and the skin itself.
The endoderm, which is inside the body of the human embryo, coagulates into a tube and forms the embryonic rudiment of the future intestine. The narrow opening that communicates the embryonic gut with the yolk sac later turns into an umbilical ring. The epithelium and all glands of the digestive system and respiratory tract are formed from the endoderm.
The embryonic (primary) gut is initially closed in front and behind. In the anterior and posterior ends of the body of the embryo, invaginations of the ectoderm appear - the oral fossa (the future oral cavity) and the anal (anal) fossa. Between the cavity of the primary intestine and the oral fossa there is a two-layer (ectoderm and endoderm) anterior (oropharyngeal) plate (membrane). Between the intestine and the anal fossa there is a cloacal (anal) plate (membrane), also two-layer. The anterior (oropharyngeal) membrane ruptures at the 4th week of development. At the 3rd month, the posterior (anal) membrane breaks.
As a result of bending, the body of the embryo is surrounded by the contents of the amnion - the amniotic fluid, which acts as a protective environment that protects the embryo from damage, primarily mechanical (shock).
The yolk sac lags behind in growth and at the 2nd month of intrauterine development looks like a small sac, and then completely reduces (disappears). The abdominal stalk lengthens, becomes relatively thin and later receives the name of the umbilical cord.
During the 4th week of development of the embryo, differentiation of its mesoderm continues, which began at the 3rd week. The dorsal part of the mesoderm, located on the sides of the notochord, forms paired thickened protrusions - somites. Somites are segmented, i.e. are divided into metameric sections. Therefore, the dorsal mesoderm is called segmented. Segmentation of somites occurs gradually from front to back. On the 20th day of development, the 3rd pair of somites is formed, by the 30th day there are already 30, and on the 35th day - 43-44 pairs. The ventral part of the mesoderm is not subdivided into segments. It forms two plates on each side (an unsegmented part of the mesoderm). The medial (visceral) plate is adjacent to the endoderm (primary gut) and is called the splanchnopleura. The lateral (outer) plate is adjacent to the body wall of the embryo, to the ectoderm, and is called the somatopleura.
From the splanchno- and somatopleura, the epithelial cover of the serous membranes (mesothelium), as well as the lamina propria of the serous membranes and the sub-serous base, develop. The mesenchyme of the splanchnopleura is also used to build all layers of the digestive tube, except for the epithelium and glands, which are formed from the endoderm. The space between the plates of the non-segmented part of the mesoderm turns into the body cavity of the embryo, which is subdivided into the peritoneal, pleural and pericardial cavities.

Fig. 3. Cross section through the body of the embryo (diagram): 1 - neural tube; 2 - chord; 3 - aorta; 4 - sclerotome; 5 - myotome; 6 - dermatome; 7 - primary intestine; 8 - body cavity (whole); 9 - somatopleura; 10 - splanchnopleura.
The mesoderm on the border between the somites and the splanchnopleura forms nephrotomas (segmental legs), from which the tubules of the primary kidney and the sex glands develop. From the dorsal part of the mesoderm - somites - three primordia are formed. The anteromedial section of the somites (sclerotome) is used to build skeletal tissue, which gives rise to cartilage and bones of the axial skeleton - the spine. Lateral to it lies the myotome, from which skeletal musculature develops. In the posterolateral part of the somite there is an area - the dermatome, from the tissue of which the connective tissue basis of the skin - the dermis - is formed.
In the head section, on each side of the embryo, from the ectoderm at the 4th week, the rudiments of the inner ear (first the auditory fossae, then the auditory vesicles) and the future lens of the eye are formed. At the same time, the visceral parts of the head are rebuilt, which form the frontal and maxillary processes around the mouth bay. Posterior (caudal) of these processes, the contours of the mandibular and sublingual (hyoid) visceral arches are visible.
On the front surface of the body of the embryo, elevations are visible: cardiac, and behind it - hepatic tubercles. The deepening between these hillocks indicates the place of formation of the transverse septum - one of the rudiments of the diaphragm. Caudal to the hepatic tubercle is the abdominal stalk containing large blood vessels and connecting the embryo to the placenta (umbilical cord). The length of the embryo by the end of the 4th week is 4-5 mm.

Fifth to eighth weeks

In the period from the 5th to the 8th week of the embryo's life, the formation of organs (organogenesis) and tissues (histogenesis) continues. This is the time of early development of the heart, lungs, complication of the structure of the intestinal tube, the formation of visceral arches, the formation of capsules of the sense organs. The neural tube closes completely and expands in the head (future brain). At the age of about 31-32 days (5th week), the length of the embryo is 7.5 mm. Fin-like rudiments (kidneys) of the hands appear at the level of the lower cervical and 1st thoracic segments of the body. By the 40th day, the rudiments of the legs are formed.
At the 6th week (the parietococcygeal length of the embryo is 12-13 mm), the bookmarks of the outer ear are noticeable, from the end of the 6-7th week - the bookmarks of the fingers and then the legs.
By the end of the 7th week (the length of the embryo is 19-20 mm), the eyelids begin to form. Thanks to this, the eyes are outlined more clearly. At the 8th week (embryo length 28-30 mm) the laying of the embryonic organs ends. From the 9th week, i.e. from the beginning of the 3rd month, the embryo (parietococcygeal length 39-41 mm) takes the form of a human and is called a fetus.

Third to ninth months

Starting from three months and throughout the entire fetal period, further growth and development of the formed organs and body parts occur. At the same time, the differentiation of the external genital organs begins. Fingernails are laid. From the end of the 5th month (length 24.3 cm), eyebrows and eyelashes become noticeable. At the 7th month (length 37.1 cm), the eyelids open, fat begins to accumulate in the subcutaneous tissue. At the 10th month (length 51 cm), the fetus is born.

Critical periods of ontogenesis a

In the process of individual development, there are critical periods when the sensitivity of the developing organism to the effects of damaging factors of the external and internal environment is increased. There are several critical periods of development. These are the most dangerous periods:
1) the time of development of germ cells - ovogenesis and spermatogenesis;
2) the moment of fusion of germ cells - fertilization;
3) implantation of the embryo (4-8th day of embryogenesis);
4) the formation of the rudiments of axial organs (brain and spinal cord, spinal column, primary intestine) and the formation of the placenta (3-8th week of development);
5) stage of increased brain growth (15-20th week);
6) the formation of functional systems of the body and the differentiation of the genitourinary apparatus (20-24 weeks of the prenatal period);
7) the moment of birth of the child and the period of newborn - the transition to extrauterine life; metabolic and functional adaptation;
8) the period of early and first childhood (2 years - 7 years), when the formation of relationships between organs, systems and organs of organs ends;
9) adolescence (puberty - in boys from 13 to 16 years, in girls - from 12 to 15 years).
Simultaneously with the rapid growth of the organs of the reproductive system, emotional activity is activated.

Postnatal ontogenesis. Newborn period

Immediately after birth, there is a period called the neonatal period. The reason for this allocation is the fact that at this time the baby is fed with colostrum for 8-10 days. Newborns in the initial period of adaptation to the conditions of extrauterine life are divided according to the level of maturity into full-term and premature babies. Intrauterine development of full-term babies lasts 39-40 weeks, premature babies - 28-38 weeks. When determining maturity, not only these dates are taken into account, but also the mass (weight) of the body at birth.
Full-term newborns are considered to have a body weight of at least 2500 g (with a body length of at least 45 cm), and premature babies weighing less than 2500 g. In addition to weight and length, other dimensions are also taken into account, for example, chest girth in relation to body length and head circumference in relation to chest circumference. It is believed that the girth of the chest at the level of the nipples should be more than 0.5 of the body length by 9-10 cm, and the girth of the head should be no more than 1-2 cm greater than the girth of the chest.

Breast period

The next period - breast - lasts up to a year. The beginning of this period is associated with the transition to feeding "mature" milk. During the thoracic period, the highest intensity of growth is observed, compared with all other periods of extrauterine life. Body length increases from birth to one year 1.5 times, and body weight triples. From 6 months milk teeth begin to erupt. In infancy, uneven growth of the body is pronounced. In the first half of the year, babies grow faster than in the second. In each month of the first year of life, new indicators of development appear. In the first month, the child begins to smile in response to the appeal of adults to him, at 4 months. persistently tries to stand up (with support), at 6 months. tries to crawl on all fours, at 8 - makes attempts to walk, by the year the child usually walks.

Early childhood

The early childhood period lasts from 1 to 4 years. Teething ends at the end of the second year of life. After 2 years, the absolute and relative values \u200b\u200bof the annual increase in body size decrease rapidly.

First childhood

From the age of 4, the period of the first childhood begins, which ends at the age of 7. Starting from the age of 6, the first permanent teeth appear: the first molar (large molar) and the medial incisor in the lower jaw.
The age from 1 to 7 years is also called the period of neutral childhood, since boys and girls hardly differ from each other in size and body shape.

Second childhood period

The period of the second childhood lasts for boys from 8 to 12 years, for girls - from 8 to 11 years. During this period, sex differences in the size and shape of the body are revealed, and an increased growth of the body in length begins. Girls' growth rates are higher than boys', as girls' puberty begins on average two years earlier. Increased secretion of sex hormones (especially in girls) leads to the development of secondary sexual characteristics. The sequence of appearance of secondary sexual characteristics is fairly constant. In girls, mammary glands form first, then pubic hair appears, then - in the armpits. The uterus and vagina develop simultaneously with the formation of the mammary glands. To a much lesser extent, the process of puberty is expressed in boys. Only by the end of this period, they begin to accelerate the growth of the testicles, scrotum, and then - the penis.

Teenage years

The next period - adolescence - is also called puberty, or puberty. It continues in boys from 13 to 16 years old, in girls from 12 to 15 years old. At this time, there is a further increase in growth rates - a pubertal leap that affects all body sizes. The greatest gains in body length in girls occur between 11 and 12 years old, in body weight - between 12 and 13 years. In boys, an increase in length is observed between 13 and 14 years, and an increase in body weight is observed between 14 and 15 years. The growth rate of body length is especially high in boys, as a result of which at 13.5-14 years old they overtake girls in body length. In connection with the increased activity of the hypothalamic-pituitary system, secondary sexual characteristics are formed. In girls, the development of the mammary glands continues, there is growth of hair on the pubis and in the armpits. The clearest indicator of a woman's puberty is the first menstrual period.
During adolescence, boys are intensely puberty. By the age of 13, they have a change (mutation) of their voice and pubic hair, and at 14 they have hair in the armpits. At the age of 14-15, boys have their first wet dreams (involuntary eruptions of sperm).
Boys, in comparison with girls, have a longer puberty period and a more pronounced pubertal growth spurt.

Adolescence

Adolescence lasts for boys from 18 to 21 years, and for girls - from 17 to 20 years. During this period, the process of growth and formation of the organism is basically completed and all the main dimensional characteristics of the body reach a definitive (final) value.
In adolescence, the formation of the reproductive system is completed, the maturation of the reproductive function. The ovulatory cycles in a woman, the rhythm of testosterone secretion and the production of mature sperm in a man are finally established.

Mature, old, old age

In adulthood, the shape and structure of the body changes little. Between the ages of 30 and 50, body length remains constant, and then begins to decrease. In old and senile age, gradual involutive changes in the body occur.

Individual differences in the process of growth and development

Individual differences in growth and development can vary widely. The existence of individual fluctuations in the processes of growth and development served as the basis for the introduction of such a concept as biological age, or age of development (as opposed to the passport age).
The main criteria for biological age are:
1) skeletal maturity - (the order and timing of skeletal ossification);
2) dental maturity - (timing of eruption of milk and permanent teeth);
3) the degree of development of secondary sexual characteristics. For each of these criteria of biological age - "external" (skin), "dental" and "bone" - rating scales and normative tables have been developed to determine the chronological (passport) age by morphological features.

Factors influencing individual development

Factors influencing individual development (ontogenesis) are subdivided into hereditary and environmental (influence of the external environment).
The degree of hereditary (genetic) influence is not the same at different stages of growth and development. The impact of hereditary factors on total body size increases from the neonatal period (tm) to the second childhood, followed by a weakening by 12-15 years.
The influence of environmental factors on the processes of morphological and functional maturation of the body is clearly seen on the example of the timing of menarche (menstruation). Studies of growth processes in children and adolescents in different geographic zones have shown that climatic factors have almost no effect on growth and development, if the living conditions are not extreme. Adaptation to extreme conditions causes such a profound restructuring of the functioning of the whole organism that it cannot but affect the growth processes.

Dimensions and proportions, body weight

Among the body sizes, total (from the French total - entirely) and partial (from the Latin pars - part) are distinguished. Total (general) body sizes are the main indicators of a person's physical development. These include body length and weight, and chest girth. Partial (partial) body sizes are terms of the total size and characterize the size of individual body parts.
Body sizes are determined during anthropometric examinations of various population groups.
Most of the anthropometric indicators have significant individual fluctuations. Table 2 shows some averaged anthropometric indicators in postnatal ontogenesis e.
Body proportions depend on the age and gender of the person (Fig. 4). Body length and its age-related changes are usually individual. So, for example, the differences in the body length of newborns with normal gestational age are within 49-54 cm.The greatest increase in the body length of children is observed in the first year of life and averages 23.5 cm.In the period from 1 to 10 years, this indicator gradually decreases on average by 10.5 - 5 cm per year. From the age of 9, sex differences in growth rate begin to appear. Body weight from the first days of life and until about 25 years of age in most people gradually increases, and then remains unchanged.

Fig. 4 Changes in the proportions of body parts in the process of human growth.
KM is the middle line. The numbers on the right show the ratio of body parts in children and adults, the numbers below show age.
table 2
Body length, mass and surface area in postiatal orthogyneisis

Table 2
After 60 years, body weight, as a rule, begins to gradually decrease, mainly as a result of atrophic changes in tissues and a decrease in their water content. The total body weight consists of a number of components: the mass of the skeleton, muscles, adipose tissue, internal organs and skin. For men, the average body weight is 52-75 kg, for women - 47-70 kg.
In old and senile age, characteristic changes are observed not only in the size and weight of the body, but also in its structure; these changes are studied by the special science of gerontology (gerontos - old man). It should be emphasized that an active lifestyle, regular physical education, slow down the aging process.

Acceleration

It should be noted that over the past 100-150 years there has been a noticeable acceleration of the somatic development and physiological maturation of children and adolescents - acceleration (from Latin acceleratio - acceleration). Another term for the same trend is “epoch-making shift”. Acceleration is characterized by a complex set of interrelated morphological, physiological, and mental phenomena. To date, the morphological indicators of acceleration have been determined.
Thus, the body length of children at birth over the past 100-150 years has increased by an average of 0.5-1 cm, and the weight - by 100-300 g. During this time, the weight of the mother's placenta has also increased. An earlier alignment of the ratios of the girths of the chest and head (between the 2nd and 3rd months of life) is noted. Modern one-year-old children are 5 cm longer and 1.5-2 kg heavier than their peers in the 19th century.
Over the past 100 years, the body length of preschool children has increased by 10-12 cm, and among schoolchildren - by 10-15 cm.
In addition to an increase in body length and weight, acceleration is characterized by an increase in the size of individual parts of the body (segments of the limbs, the thickness of skin and fat folds, etc.). Thus, the increase in chest girth in relation to the increase in body length was small. The onset of puberty in modern adolescents occurs about two years earlier. The acceleration of development also affected the motor functions. Modern adolescents run faster, jump further in length from a place, more times pull themselves up on the crossbar (horizontal bar).
An epochal shift (acceleration) affects all stages of human life, from birth to death. For example, the body length of adults also increases, but to a lesser extent than that of children and adolescents. So, at the age of 20-25, the body length of men increased by an average of 8 cm.
Acceleration covers the entire body, affecting the size of the body, the growth of organs and bones, the maturation of the gonads and skeleton. In men, changes in the acceleration process are more pronounced than in women.
A man and a woman are distinguished by sex characteristics. These are primary signs (genitals) and secondary (for example, the development of pubic hair, the development of the mammary glands, voice changes, etc.), as well as physique features, the proportions of body parts.
The proportions of the human body are calculated as a percentage according to the measurement of the longitudinal and transverse dimensions between the boundary points set on various protrusions of the skeleton.
The harmony of body proportions is one of the criteria for assessing the state of human health. With a disproportion in the structure of the body, one can think of a violation of growth processes and the reasons that caused it (endocrine, chromosomal, etc.). On the basis of calculating the proportions of the body in anatomy, three main types of human constitution are distinguished: mesomorphic, brachymorphic, dolichomorphic. The mesomorphic body type (normosthenics) includes people whose anatomical features are close to the average parameters of the norm (taking into account age, gender, etc.). In people of a brachymorphic body type (hypersthenics), transverse dimensions prevail, the muscles are well developed, they are not very tall. The heart is located transversely due to the high-standing diaphragm. In hypersthenics, the lungs are shorter and wider, the loops of the small intestine are located mainly horizontally. Persons of a dolichomorphic body type (asthenics) are distinguished by the predominance of longitudinal dimensions, have relatively longer limbs, poorly developed muscles and a thin layer of subcutaneous fat, narrow bones. Their diaphragm is located lower, so the lungs are longer, and the heart is almost vertical. Table 3 shows the relative sizes of body parts in people of different body types.
Table 3.

Conclusion

What can be summed up above?
Human growth is uneven. Each part of the body, each organ develops according to its own program. If we compare the growth and development of each of them with a long-distance runner, then it is easy to find that during this many years of "running" the leader of the competition is constantly changing. In the first month of embryonic development, the head is in the lead. In a two-month-old fetus, the head is larger than the body. This is understandable: the brain is in the head, and it is the most important organ that coordinates and organizes the complex work of organs and systems. The development of the heart, blood vessels and liver also begins early.
In a newborn baby, the head reaches half of its final size. Up to 5-7 years of age, there is a rapid increase in body weight and length. In this case, the arms, legs and body grow alternately: first, the arms, then the legs, then the body. Head size increases slowly during this period.
Growth is slower at primary school age from 7 to 10 years. If earlier arms and legs grew faster, now the torso becomes the leader. It grows evenly so that the proportions of the body are not disturbed.
In adolescence, the arms grow so intensively that the body does not have time to adapt to their new sizes, hence some awkwardness and sweeping movements. After that, legs begin to grow. Only when they reach their final size, the trunk is included in the growth. First, it grows in height, and only then begins to grow in width. During this period, a person's physique is finally formed.
If we compare the parts of the body of a newborn and an adult, it turns out that the size of the head has only doubled, the body and arms have become three times larger, and the length of the legs has increased five times.
An important indicator of the development of the body is the appearance of menstruation in girls and emissions in boys, it speaks of the onset of biological maturity.
Along with the growth of the body, its development proceeds. Human growth and development in different people occur at different times, therefore, anatomists, doctors, physiologists distinguish between calendar age and biological age. Calendar age is calculated from the date of birth; biological age reflects the degree of physical development of the subject. The latter is different for each person. It may happen that people who are at the same biological age may differ in calendar by 2-3 years, and this is completely normal. Girls tend to develop faster.

Literature

1. Medical scientific and educational-methodical journal No. 28 [October 2005]. Section - Lectures. The title of the work is PERIODS OF CHILDHOOD. Author - P.D. Vaganov
2. Vygotsky L.S. Collected works in 6 volumes. Volume 4.
3. Vygotsky L.S. article "Problems of age periodization of child development"
4. Obukhova L.F. textbook "Child (developmental) psychology". Fundamental and Clinical Physiology / Ed. By A.G. Kamkina and A.A. Kamensky. - M .: "Academy", 2004.
5. Schmidt R., Tevs G. Human Physiology: Per. from English. - M .: Mir, 1996.
6. Dragomilov A.G., Mash R.D. Biology: Human. - 2nd ed., Revised. - M .: Ventana-Graf, 2004.
7. Sapin. M.R., Bryksina Z.G. Anatomy and physiology of children and adolescents: Textbook. manual for stud. ped. Universities. - M .: Publishing Center "Academy", 2002.
8. Chusov Yu.N. Human physiology: Textbook. manual for ped. Schools (special No. 1910). - M .: Education, 1981.
9. Encyclopedia "Around the World"
10. "Rusmedservice"
11. Encyclopedia "Wikipedia"

Like any living organism, a person is born, grows, multiplies, grows old and dies A person's age is calculated from the moment of his birth. On average, human life expectancy in developed countries is 73 years for men and 77 years for women.

Birth. Before childbirth, a woman begins labor pains - involuntary contractions of the uterus, they are helped by a periodic contraction of the abdominal muscles. The baby's lungs are straightened out, with the first cry, he begins to breathe on his own.

After the baby is born, the umbilical cord (umbilical cord) is tied in two places and then cut between the constrictions. The child becomes independent.

Newborn and nursing baby. This small but crucial period in a person's life does not last long. Up to a month, a child is considered a newborn, up to a year - an infant.

A newborn baby is weak and helpless. Thanks to innate reflexes, he sucks on the mother's breast. After a month, his body weight increases significantly, his movements become more complicated. The child can make grasping movements, masters the basics of communication. In infancy, the baby grows especially quickly. From about 6 months, milk teeth begin to erupt. A number of organs (eye, inner ear) quickly reach almost adult size.

During this period, the child should receive adequate nutrition. Babies absorb the proteins, fats and carbohydrates of human milk best of all, which is why breastfeeding is so important. In addition, breast milk contains antibodies and thus protects the baby from many diseases.

Childhood. In the period from 1 to 3 years, all baby teeth erupt in a child, he grows quickly and gains weight. The child's speech and memory are developed. He begins to orient himself in his surroundings, actively learns the world. During this period, play is of great importance for the baby.

Puberty in girls begins at 11-12 years old, in boys a little later - at 12-13 years old. At this time, the proportions of the body change, secondary sexual characteristics appear; in girls, the pelvis expands. the hips are rounded, the mammary glands are enlarged; in boys, the growth of the larynx begins, the voice breaks.

Teenage years. At 12-16 years of age, adolescents have increased secondary sexual characteristics. Girls have menstruation: this is a sign that eggs have begun to develop and mature in the ovaries. By the age of 15-16, boys begin to grow hair on the face, body, in the armpits, involuntary discharge of sperm appears - emissions - the first sign of puberty in young men.

Adolescence. This age (16-21 years) coincides with the ripening period. At this age, the growth and development of the body is basically completed, all organ systems practically reach their maturity.

The structure of the body in mature age (22-60 years old) changes little, and in the elderly (61-74 years old) and senile (over 75 years old), a restructuring characteristic of these ages can be traced: metabolism slows down, there is a decrease in the performance of all organ systems. An active lifestyle, regular physical education slows down the aging process.

The embryo does not immediately look like a little man. Indeed, during intrauterine development, a person, like all other mammals, goes through the path of development of his biological species: at first he looks like a lancelet, then he resembles a small fish, then he has the features of amphibians and reptiles. All these transformations occur rather quickly, and by the beginning of the 6th week from the moment of fertilization, the embryo already looks like a small man, although its length is only slightly more than 1 cm.The spine of the embryo during this period is still cartilaginous, but there are already hoops on the arms and legs. he starts to beat his heart.
When a person is born, his brain volume is very small. Most of the human brain is formed after birth. A newborn child hears sounds well, but only after a year he learns to accurately determine the sources of these sounds.
When a child is born, he has practically no motor skills, so he must first learn to hold his head, then crawl, walk, etc. For most children, the main stages in the development of motor skills are as follows:
9 months - creeps;
1 year old - starts to walk;
1.5 years old - can walk well;
2.0 years - runs confidently;
3.0 years - learns to kick the ball;
4.0 years - can jump on one leg;
5.0 years - can walk along a line drawn on the ground;
6.0 years old - can jump in length and height well.

As the body develops and the child matures, the proportions of his body change. The head decreases in comparison with the length of the body, while the legs and arms become relatively longer.

Test your knowledge

What are labor pains?
When does a child begin to navigate the environment?
What is typical for a newborn baby?
What period of a person's life covers the breast period?
When does puberty start in girls?
What are the characteristics of development in adolescence?
What stage in a person's life coincides with the period of maturity?

Think

Why can't an unborn baby in a mother's body cry?

In human development, the newborn and breast stages, childhood, adolescence and adolescence, mature, old and senile age are distinguished.

OPTION 1

1) Female gametes are called:

A. Follicles B. Eggs C. Sperm

2) Human sex cells contain:

A. 46 chromosomes B. 50 chromosomes C. 23 chromosomes

3) Male gametes are formed:

A. In the prostate gland B. In the testes B. In the vas deferens

4) The period of development of the egg is:

A. 30 days B. 28 days C. 25 days

5) Implantation and development of the embryo occurs:

Pick all the correct answers.

6) The male reproductive system includes:

A) testes B) penis

B) ovaries D) prostate

7) Fertilization is fusion:

A) oocytes B) body cells

B) eggs and sperm D) male and female reproductive cells

8) Placenta:

A) a child's place B) an organ through which communication with the mother's body is carried out

C) embryo D) fetus

9) The testes, like the ovaries, are glands:

A) internal secretion B) external secretion C) mixed secretion

10) The female and male reproductive systems are similar in that:

A) form the same number of cells

C) perform the function of bearing the fetus

D) form sex cells

Insert the missing words.

11) Male and female organisms take part in sexual reproduction, producing sex cells:(1) ... and (2) ..., when they merge, (3) ...

12) The human zygote contains (1) ... chromosomes, with the combination of sex chromosomes XX is born (2) ..., and XY - (3) ...

13) As a result of involuntary contractions (1) ... the child is born, with the first cry, they straighten him out (2) ..., and after being cut off (3) ... he becomes an independent creature.

14) Determine the organs that form the female reproductive system (explain the numbers).

Examination in biology, grade 8, Sonin UMK.

REPRODUCTION. HUMAN DEVELOPMENT. AGE PROCESSES.

OPTION 2

Choose one correct answer .

1) Female gametes are formed:

A. In the fallopian tubes B. In the uterus C. In the ovaries

2) Fertilization of the egg occurs:

A. In the fallopian tube B. In the ovary C. In the uterus

3) The human zygote contains:

A. 23 chromosomes B. 46 chromosomes B. 92 chromosomes

4) The gestation period is:

A. 38 weeks B. 40 weeks C. 42 weeks

5) With the first cry, the child begins to function actively:

A. Circulatory system B. Digestive system B. Respiratory system

Pick all the correct answers.

6) The female reproductive system includes:

A) testes B) uterus

B) ovaries D) fallopian tubes

7) The placenta is permeable to:

A) oxygen and nutrients B) alcohol and nicotine

B) metabolic products of the fetus D) mother's blood cells

8) A child aged 6 months corresponds to the period:

A) newborn B) childhood

B) breast D) adolescent

9) The ovaries, in contrast to the testes:

A) paired glands B) mixed secretion glands

B) produce female germ cells D) are located in the abdominal cavity

10) The ability of a person to reproduce sexually:

A) makes it related to other organisms B) distinguishes it from other organisms

B) has the greatest similarity with placental mammals

D) ensures the transmission of traits to offspring from both parents

Insert the missing words.

11) Male sex glands - (1) ... synthesize the germ cells (2) ..., the nutrition and development of which is provided by the seminal fluid produced by (3) ... the gland.

12) Eggs develop into (1) ..., in special bubbles - (2) ..., the ripening period is (3) ... days.

13) Fertilization takes place in the uterine (1) ... the zygote is implanted into the wall (2) ... where the multicellular (3) ...

14) Determine the organs that form the male reproductive system (give explanations to the numbers).