Gonads and germ cells. The human body develops from a fertilized egg, which is formed as a result of the fusion of two cells: a male - sperm and a female - egg (Fig. 131). Sex cells are formed in the gonads.
A child is born with sex glands and genital organs specific to a given sex - internal and external.
Female genital organs
The female reproductive gland is ovary. This is a paired female reproductive gland located at the upper entrance to the small pelvis on both sides of the uterus (Fig. 132).
The ovary consists of two layers - the cortex and the medulla. Egg cells are formed in the cortex. The medulla consists of connective tissue containing blood vessels and nerves.
The ovary produces eggs - female reproductive cells, from which a new organism develops as a result of fertilization.
The ovary produces sex hormones, on which not only the activity of the woman’s genital organs depends, but also the normal activity of the entire female body.
Rice. 131. Sex cells:
A - sperm; B - ovoid; 1 - sperm head; 2 - middle or connecting department; 3 - sperm tail; 4 - follicular cells surrounding the egg; 5 - nucleus of the egg cell.
Adjacent to the posterior edge of the testicle is its epididymis, from which extends the vas deferens, 45-50 mm long. To the head10-12 very thin efferent tubules pass from the epididymis from the testicle. The seed is carried out of the testicle through these tubules. In the seminiferous tubules of the testicle, with the onset of puberty, the rudiments of germ cells - spermatoblasts - begin to divide, as a result of which male germ cells are formed - sperm, or livelies(Fig. 131). The zhivchik consists of a head, a middle part and a tail, the contractions of which ensure the movement of sperm. The speed of movement of the live bait is about 2-3 mm per minute. The final maturation and accumulation of sperm occurs in the epididymis. Male gonads, unlike female ones, produce sperm continuously.
From the time a young man's body matures, many millions of sperm are born per day in the convoluted tubules of the testicles. About 500 million or more can be thrown out at a time. Mature larvae can live in a male body for about a month, then they age and disappear.
During sexual arousal, sperm accumulated in the epididymis, together with epididymal secretions, move along the vas deferens to the seminal vesicles. The secretion of the epididymis thins the environment, providing greater mobility of sperm, and in addition, nourishes sperm not only inside the seminal vesicle, but also during the eruption of semen. During sexual arousal, the secretion of the prostate gland is simultaneously produced, which covers the urethra on both sides as it exits the bladder. The secretion of the gland activates sperm motility.
At the moment of greatest sexual arousal, first secretions from the prostate gland are released into the posterior part of the urethra, then spermatozoa and, finally, secretions from the seminal vesicles. The secretion of the prostate gland and seminal vesicles mixes with sperm to form sperm. With each sexual intercourse, 1-6 cm 3 of sperm is released. Semen is ejected through the external opening of the urethra, which opens at the head of the penis.
The skin of the penis at the base of the glans forms a fold - the foreskin. On its inner surface there are sebaceous glands of various sizes, the secretion of which is involved in the formation of a whitish lubricant.
, pregnancy, childbirth
most often occurs in the expansion of the female oviduct. Spermatozoa, ejaculated with sperm into the vagina, due to their exceptional activity and mobility, move into the uterine cavity and pass it to the oviductsand in one of them they meet with a mature egg. Here the sperm (one of many) penetrates the egg and fertilizes it.
The fertilized egg, with a flow of liquid, moves through the oviduct to the uterus, turning into a lump of cells surrounded by a membrane equipped with villi.
As the fertilized egg develops, it continues its movement to the uterus, where it reaches approximately 3-6 days after fertilization. In the uterus, already prepared by ovarian hormones, the villi of the fertilized egg penetrate into the swollen mucous membrane, which grows greatly and soon closes over the fertilized egg. If the egg is fertilized rena and the embryo develops normally in the uterus and stops. The corpus luteum will not disappear within 5-6 months. It grows and, with its increasing hormonal influence, promotes the growth and further attachment of the egg, and also prevents the maturation of eggs in the ovary.
Rice.134. Position of the baby in the womb:
1-bladder; 2 - placenta, or baby's place; 3 - rectum; 4 - vagina.
At the site of attachment of the fertilized egg to the wall of the uterus, a placenta, or a children's place (Fig. 134).
The formation of the placenta ends by the end of the third month of pregnancy, and in the future it only increases in size.
Placenta- an organ through which the fetus is connected to the mother’s body. Through it, the fetus is nourished, its respiratory and excretory functions are carried out. Many protective bodies (antibodies) pass through the placenta from mother to fetus.
Nutrients are supplied through the umbilical cord, which connects the fetus to the mother's body. It looks like a cord 50-60 cm long, 1.5-2 cm thick. The umbilical cord begins in the fetal navel and ends in the placenta.
The fetus developing in the uterus is located in special membranes that form a kind of bag filled with amniotic fluid. These waters enable the fetus to move freely in the sac, develop, and protect it from accidental injuries.
The membranes that contain the developing fetus are called the afterbirth.
A normal pregnancy lasts 9 months. During this time, a child weighing about 3 kg or more and 50-52 cm tall develops from a fertilized egg of microscopic size.
Pregnancy ends with childbirth. As a result of intense work of the muscles of the uterus, the child is pushed into the pelvis, then the abdominal muscles contract, and the child is born.
Mother and child are still connected by a pulsating umbilical cord. The doctor or midwife first ties the umbilical cord near the newborn's abdomen and then cuts it. In a child, the placental is replaced by the pulmonary, and pulmonary disease occurs. Soon after the baby is born, the placenta comes out of the uterus.
Now the child will feed on mother's milk for almost a year. Breast milk contains proteins, fats, sugars and everything necessary for the growth and development of a child, including vitamins, enzymes, and protective against diseases (antibodies).
A few weeks (and sometimes months) after childbirth, the maturation of eggs in the ovary resumes, as indicated by the onset of menstruation. The woman again becomes capable of conceiving a child.
Post-embryonic human development
Age periodization. According to a number of signs, the entire life path of a person from conception to the natural end can be divided into periods, or stages. There are no clearly defined boundaries between these periods; they are largely arbitrary.
Several factors have been proposed as criteria for age periodization. Some researchers take the maturation of the gonads and the intensity of body growth as the basis for periodization, others - the time of appearance and change of teeth, and still others - the degree of development of the central nervous system. The most common is the periodization of children, distinguishing the period of newborn, nursery, preschool and school age. This division reflects the existing system of child care institutions.
It must be assumed that a truly scientific classification cannot be based on any one characteristic. In each individual period of life, a set of characteristics (type of nutrition, motor activity, puberty, etc.) comes to the fore. The most appropriate way to organize work on teaching and raising children is considered to be such a division of a child’s development into periods in which the complex of his anatomical and physiological characteristics and living conditions, upbringing and training is taken as a basis.
In modern science there is still no unified classification of periods of growth and development and their age boundaries. The Symposium on the Problem of Age Periodization in Moscow (1965) recommended the following age periodization, which is not accepted by all researchers:
1) newborn - 1 - 10 days;
2) breast age - 10 days - 1 year;
3) early childhood -1-3 years;
4) first childhood - 4 - 7 years;
5) second childhood -8-12 years old boys,
8-11 years old girls;
6) adolescence - 13-16 years old boys,
12-15 years old girls;
7) adolescence - 17-21 years old boys,
16-20 years old girls;
8) mature age, period I - 22-35 years old men,
22-35 years old women; mature age, II period - 36-60 years old men,
36-55 years old women;
9) old age - 61 -74 years old men,
56-74 years old women;
10) old age - 75-90 years;
11) long-livers - 90 years and above.
From the moment of birth to death, the human body exhibits specific structural features, biochemical processes, functions of the body as a whole and its individual systems, which change during different periods of its life. These changes are caused by hereditary factors, which to a certain extent determine the stages of growth and development. However, training and upbringing, nutrition and hygienic living conditions, the child’s communication with people around him through speech, sports and work activity and other factors that make up the essence of a person’s social life are of decisive importance for the manifestation of these hereditary factors and the formation of age-related characteristics.
Human lifecontinuous development process. The beginning of walking and the further development of motor function, the child’s first words and the development of speech function, the transformation of a child into a teenager during puberty, the continuous development of the central nervous system, the complication of reflex activity - these are just examples of a huge number of continuous changes in the body.
Rice. 135. Changes in body proportions with age
The growth and development of the body and its individual organs occurs unevenly, heterochronically. Uneven growth of the body in length, individual organs and tissues, and weight of the child is accompanied by a number of age-related changes. There is also a change inportions of the child’s body (Fig. 135). A newborn differs from an adult in having relatively short limbs, a large body and a large head. The height of a newborn's head is 1/4 body length, in a child of two years - 1/5, of six years - 1/6, 12 years - 1/7 and in adults - 1/8. With age, head growth slows down and limb growth increases. Before the onset of puberty, there are no gender differences in body proportions, but during puberty (puberty), boys' limbs become longer, their torso shorter, and their pelvis narrower than girls'.
Three periods of different proportions between body length and width can be seen: from 4 to 6 years, from 6 to 15 years, and from 15 years to adulthood. If in the prepubertal period general height increases due to the growth of the legs, in the pubertal period - due to the growth of the torso.
The unevenness of body growth in length is manifested as follows: in the first year of life, height increases by 25 cm and reaches 75 cm. In the second year, the growth rate slows down - it increases only by 10 cm. In subsequent years, up to 6-7 years, the growth rate are decreasing even more. By the beginning of primary school age, growth increases by 7-10 cm per year, and at the age of 8-10 years up to 3-5 cm. During puberty, growth rates increase again, the annual increase is 5-10 cm. Girls have the greatest increase in growth Due to puberty, it is observed at 12 years of age, in boys - at 15 years of age. By this period, boys catch up and then surpass girls in height.
Growth is generally completed by the age of 19 for girls and by the age of 20 for boys.
From the neonatal period to adulthood, body length increases by 3.5 times, body length by 3 times, arm length by 4 times, and leg length by 5 times.
Uneven growth is an adaptation developed by evolution. The rapid growth of the body in length in the first year of life is associated with an increase in body weight, and the slowdown in growth in subsequent years is due to the manifestation of active processes of differentiation of organs, tissues, cells, and functional systems.
It should be borne in mind that development leads to morphological and functional changes, and growth leads to an increase in the mass of tissues, organs and the entire body. During the normal development of a child, both of these processes are closely interrelated. However, periods of intense growth may not coincide with periods of intense differentiation.
Increased differentiation causes growth retardation. The increase in the mass of the brain and spinal cord generally ends by the age of 8-10, almost reaching the mass of an adult, while the functional improvement of the nervous system continues for a long time.
The maturation of the motor analyzer and the innervation apparatus of muscles occurs at 13-14 years of age, going through a number of stages of improving motor function. At the same time, at 15-18 years of age, further intensive growth and differentiation of muscle tissue occurs. The uneven development of the cardiovascular system is manifested as follows: from birth to two years it grows rapidly, but histological differentiation changes slightly; from 2 to 6 years, growth changes and differentiation are slowed down, both processes proceed moderately; from 7 to 10 years, the size and volume of the heart increases, but significant structural changes in the muscle do not occur; from 11-13 years old it begins to grow rapidly again, and the finest differentiation occurs in the cellular elements. Uneven development is accompanied by growth retardation.
Weight. The greatest increase in body weight occurs in the first year of life. By the end of the first year of life, body weight triples and reaches 9-10 kg. By the end of the second year it reaches 12-13 kg. Subsequently, the weight increases by 2 kg per year. With the onset of puberty, weight gain in girls reaches 4-5 kg, and by the age of 14-15 - 5-8 kg, then the annual weight gain again amounts to 2 kg. In boys, from the age of 13-14 years, weight gain is 7-8 kg per year. Subsequently, in boys, as in girls, the rate of weight gain slows down. The weight of boys and girls under 10 years of age is almost the same. From the age of 15, the mass of boys begins to exceed the mass of girls, and this lead continues throughout the rest of their lives.
Tasks
Physical education, 6th grade
In all matters only one correct answer.
Physical education teacher Musin A.N.
The formation of the human body ends by:
14-15 years old
17-18 years old
19-20 years old
22-25 years old
Athletics - including:
running, walking, jumping, throwing
running, swimming, jumping
rhythmic gymnastics, football
volleyball basketball
Alina Kabaeva is famous:
figure skater
gymnast
swimmer
tennis player
Sprinting refers to:
sprint
sports games
weightlifting
bobsleigh
What game is a volleyball used in?
football
pioneerball
basketball
handball
Name the winter Olympic sport, which is a high-speed descent from the mountains along specially equipped ice tracks on a controlled sleigh.
bobsled
luge
short track
curling
What is the name of the game of football on motorcycles?
motorfoot
motorball
bikefoot
footmotoball
In 2006, he became the best football player according to the most authoritative sports publications in the country - the weekly Football, the newspapers Sport Express and Soviet Sport. Who is this?
Evgeni Plushenko
Andrey Arshavin
Marat Safin
Alexander Ovechkin
In 2014, the World Hockey Championship was held in Minsk. The following team became the world champion:
Sweden
Canada
Russia
Finland
It is believed that this man founded the Olympic Games after defeating King Augeias.
Hades
Poseidon
Hercules
Hermes
What is the name of the residential complex for athletes participating in the Olympic Games?
Olimpic village
Sports town
Champions village
Glade of record holders
13. What color is the Olympic flag?
White
Yellow
Red
Blue
14. At the Olympic Games in Sochi there were representatives from:
88 countries
50 countries
106 countries
37 countries
15. The total number of medals won by Russian athletes at the Olympic Games in Sochi was:
ANSWERS:
1. Answer: The formation of the human body ends by the age of 22 - 25 years. During periods of growth and development of the body, the mass and surface of the body increases, which is due to the development of tissues, organs and individual parts of the body. At the same time, the functions of organs and systems develop.
2. Answer: Athletics - including running, walking, jumping and throwing. Combines the following disciplines: , (road running) and (cross-country running). One of the main and most popular sports.
3. Answer: Alina Kabaeva is a gymnast, Honored Master of Sports. She is the only gymnast in the world included in the Guinness Book of Records, since at the age of 15 she became the absolute European champion among adults.
4. Answer: Golf is a sports game in which individual participants or teams compete by hitting a small ball into special holes with clubs, trying to cover the allotted distance in the minimum number of strokes.
5. Answer: Sprint is a type of running performed at a very fast pace and only over short distances (up to 400 meters).
6. Answer: Pioneerball is a sports game with a ball, similar in rules to. The game is played from to.
7. Answer: Winter Olympic sport, which is a high-speed descent from the mountains along specially equipped ice tracks on a controlled bob sleigh. The birthplace of bobsleigh is Switzerland.
8. Answer: Motoball is one of the types of motorsports, it is a game of racing. The game is played on a field the size of a football field, but with slight differences in markings: there is no central circle, the goal area is shaped like a semicircle. The surface of the field is usually not dirt, but asphalt. They play with a ball that is much larger than a football. Each team has 5 people - a goalkeeper and 4 field players on motorcycles., second. In 2006, he became the best football player according to the most authoritative sports publications in the country - the weekly Football, the newspapers Sport Express and Soviet Sport.
10. Answer: In 2014, the World Hockey Championship was held in Minsk. The Russian team became the world champion, beating the Finnish team in the final match with a score of 5:2.
11. Answer: It is believed that the Olympic Games were founded by Hercules after completing his sixth labor - cleansing the barnyard of Augeas, king of Elis. Augeas possessed innumerable wealth. His herds were especially numerous. Hercules agreed to cleanse the entire huge courtyard of Augeas in one day if he gave him a tenth of his herds. Augeas accepted the offer of help, believing that it was simply impossible to complete such work in one day. When Hercules completed the task and came to Augeas to demand a reward, the king did not give him anything, and even kicked him out. Hercules took terrible revenge on the king of Elis. With a large army, he invaded Elis, defeated Augeas in a bloody battle and killed him with a deadly arrow. After the victory, Hercules gathered the army and all the booty, made sacrifices to the Olympic gods and established the Olympic Games, which were held from then on every four years on the sacred plain, planted by Hercules himself with olive trees dedicated to the goddess Pallas Athena.
12. Answer: The Olympic Village is a complex of buildings in which members of the delegations of the countries participating in the Olympic Games are located.
13. Answer: The Olympic flag is a white silk cloth with five interlocking rings of blue, black, red (top row), yellow and green (bottom row) embroidered on it.
14. Answer: At the Olympic Games in Sochi there were representatives from 88 countries.
15. Answer: The Russian team completed its performance at the Olympic Games in Sochi, having won a total of 33 medals: 13 gold, 11 silver and 9 bronze; this result allowed the hosts of the Games to win the team competition both in the number of gold and in the total number of medals.
How old does a person grow? The development and growth of our body - both the whole body and internal organs - is inconsistent and, one might say, spasmodic. The fastest increase in body weight and size occurs during the period of nine months, a small egg reaches a weight of three kilograms. But even after birth, growth does not stop, although it slows down. In the first year of life, a healthy baby grows an average of 23 centimeters, but in the second year he gains only ten centimeters. Then, up to 11 years of age in girls and 13 years of age in girls, it slows down, although it does not stop completely, so that during puberty it rapidly increases, by ten or even more centimeters at once. Then, as they say, the child “stretched out” and turned into a tall and angular teenager.
But even later, the body continues to develop in height, albeit imperceptibly - by a couple of millimeters or a centimeter per year. Previously, there was no consensus on how old a person grows. It was believed that up to twenty, although this figure is very generalized and conditional. At the age of 25, the formation of the body, all organs and vital functions is completely completed. From adolescence to twenty years, intensive work is carried out to strengthen internal organs - the heart, lungs. Sexual development occurs rapidly - a surge of hormones literally reshapes the female body, in one or two years transforming an awkward, pimply teenager with protruding collarbones and sharp knees into a seductive beauty with soft feminine features. Typically, body lengthening in girls stops at the age of sixteen to nineteen, since all development resources are used to prepare the body for procreation.
Its upward growth continues on average until twenty, and for some young men it continues further - up to 25 or even thirty years of age. At the age of 20-25, the last period of rapid growth occurs, when a person can add half a centimeter per year. This means that the internal organs have finished forming, have strengthened, become denser, and the remainder of the resources for increasing the body have been devoted to lengthening the skeleton. After this “golden age,” when a man is said to be in his prime, and a woman is said to be “in her prime,” the body’s development in this regard stops.
In the question of how old a person grows, race and genetic inheritance play a key role. and the general formation of the body in Negroid people who live in southern Asia takes place somewhat earlier. If European boys (especially in northern countries) at the age of 14 are still mere children, then in India and on the African continent they are already fully formed young men. This applies even more to girls, which is why the tradition of early marriage is connected. On the European continent, an earlier cessation of growth was also noted among southern peoples and a more extended period of maturation among northern peoples.
Heredity is also a decisive factor in how long a person grows. If both parents are tall and slim, there is a 90% chance that their children will also be taller than average. And, conversely, short people also have small children. Of course, there is still 10% left. What are these factors? Can we somehow influence them and, therefore, adjust our growth? Yes, because if you eat right and lead an appropriate lifestyle, then this, although slightly, can affect your body length.
Knowing how old a person grows, you can add an extra centimeter or two not allotted by nature. By consuming certain foods that help strengthen the bones of the spine and increase the elasticity of the intervertebral discs (cottage cheese, fatty fish, aspic or jellied meat), you can increase body growth. Special physical exercises that stretch the spine also help to increase metric characteristics. But the influence of carrots on the upward movement of our body turned out to be too exaggerated. Carrots only have a strengthening effect, like other fruits and vegetables.
Lesson type- combined
Methods: partially search, problem presentation, reproductive, explanatory and illustrative.
Goals:
Awareness of life as the highest value, the ability to build one’s relationships with nature and society on the basis of respect for life, for all living things as a unique and priceless part of the biosphere;
Diversified development of students’ personality: observation, sustainable cognitive interest, desire for self-education and application of acquired knowledge in practice;
Formation of sanitary and hygienic culture, their environmental thinking and morality.
Tasks:
Educational: to have certain environmental knowledge and hygienic knowledge is an important component of the culture of every person;
Developmental: develop cognitive and practical orientation, freedom and creative thought, general educational skills in working with popular science literature and Internet sources
Educational: educate students using this lesson for the development of a physically and morally healthy human society.
Regulatory: organize your workplace under the guidance of a teacher; determine a plan for completing tasks in the lesson, evaluate the results of your activities.
Communicative: participate in dialogue in class; answer questions from the teacher and classmates; listen and understand the speech of others; work in a small group.
Cognitive: navigate the textbook; find the necessary information in the text of an educational article.
Planned results
Subject
human influence on individual components of nature and the influence of nature on all aspects of human activity;
preparing schoolchildren for practical activities in the field of biology, ecology and medicine;
Establishing harmonious relationships with nature, with all living things, as the main value on Earth.
basic bioecological terminology and symbolism
Personal:
the formation of interest in a global problem called “ecological problem”, which is associated with the deterioration of the quality characteristics of the human environment.
Interdisciplinary: connections with such academic disciplines as biology, chemistry, physics, geography - will contribute to a higher level of skills in this course and the implementation of the tasks of pre-professional training of schoolchildren.
Lesson form- traditional
Technology - problem-based learning
Basic concepts: zygote, blastula, gastrula, fetus, newborn, infancy and toddlerhood, placenta, uterus, oviduct, ovary, umbilical cord, egg, ovum, sperm.
Learning new material
Development of the human body
The process of fertilization in higher vertebrates, including humans, occurs in the genitals. This is due to the fact that one or more sperm of a man introduced into the female body merges with an egg formed in the ovary (reproductive gland). Fertilization occurs in the oviduct, where the sperm and egg penetrate. The oviduct connects the ovary to the uterus, in which further development of the embryo occurs.
The initial stage of development of the human body is characterized by the formation of a zygote of a fertilized egg, which carries a diploid (double) set of chromosomes: one from the egg and the other from the sperm. Each pair of chromosomes is homological.
I stage of embryo development - the blastula is a single-layer multicellular vesicle, which is formed in the oviduct as a result of fragmentation of the zygote.
The 2nd stage of development of the embryo - gastrula - is characterized by the fact that the fertilized egg moves into the uterus and penetrates its wall, after which a two-layer embryo is formed from it, which already has two germ layers (layers cells) - endoderm (inner layer) and ectoderm (outer layer). Then the mesoderm (a layer of cells between the ectoderm and endoderm) appears. From these three leaves all organ systems are formed. On the side where the dividing egg contacts the wall of the uterus, embryonic membranes (placenta, bladder) are formed, and on the opposite side - the embryo itself.
During the development of the fetus, the bladder is filled with watery liquid, the placenta is embedded in the walls of the uterus with its villi. The umbilical cord connects the placenta to the fetus. The fetus develops one circle of blood circulation. “Gill slits, tail, as well as hair in the early stages of fetal development indicate the common origin of all chordates and confirm the position of the biogenetic law, which states that the individual development of an organism is a brief repetition of the development of a given species; by 9 months the fetus has fully acquired -melts all the features of the human body. Developing in an aquatic environment, it is protected from shock and moves freely. Through the placenta, the embryo receives oxygen and nutrients from the mother and returns decay products to her. This ends the embryonic stage of development of the human body.
Postpartum period characterized by two stages: newborn and infant
The physiological characteristics of the newborn stage of fetal development are characterized by the presence of unfused bones, which overlap each other, reducing the volume of the head and pelvis, which helps during the birth of a child. When the umbilical cord is ligated, an excess of carbon dioxide is created in the blood, which has a humoral effect on the respiratory center of the medulla oblongata, and as a result, the first reflex movement occurs - inhalation and screaming, and then the next innate reflex appears - sucking.
A newborn baby has a disproportionate body structure - a very large head and short limbs. The bones of the skull are not fused, there are skin films between them - fontanelles, the pelvic bones are also not fused, the spine has no bends.
The postpartum period of development lasts up to 12 months and is called the infancy period. During this period, the child masters movements, raises his head, lies on his stomach, stands on his feet, this contributes to the formation of bends in the spine: cervical, thoracic, lumbar. Baby teeth appear. The physiological characteristics of this period are associated in the child with the formation of muscles. Movements become varied, the skeleton strengthens, and the need to walk arises. During the first period of an infant, the mother feeds breast milk and feeds the baby with food containing vitamins. At this time, the child undergoes intensive development of higher nervous activity and begins to pronounce his first words.
Nursery period Child development covers the period from 1 to 3 years. At this time, his body proportions change: the volume of his head decreases, his limbs lengthen. During the development of the brain, grooves and convolutions are formed. The physiological characteristics of this period are characterized by the child’s need for independence. He switches to eating regular food. The fontanelles in the skull are overgrown, and articulate speech develops.
Preschool period lasts from 3 to 6 years. At this time, baby teeth are replaced by permanent teeth, and brain development continues. The physiological characteristics of this period are associated with the coordination of the child’s movement; speech is meaningful and associated with the development of thinking. Conditioned reflex centers of speech and writing are formed.
School period from 6 to 16 years. At this time, there is an intensive development of the musculoskeletal system, body growth, and character formation, which ends by the age of 20-25 years. After 10 years of life, the pelvic bones fuse together in a child. In accordance with the structural features of the body, children's, adolescent and youth stages of development are distinguished. The physiological characteristics of the teenage stage (13-15 years) are associated with the presence of restructuring of the body in connection with puberty. The activity of the endocrine and exocrine glands changes. This causes psychological changes (the predominance of excitation over inhibition) and physiological changes in the body (secondary sexual characteristics appear: in girls the body shape, timbre of the voice changes, and in boys - body proportions, physical development increases, the voice breaks, hair appears on the face). However, sexual formation ends only at 20-25 years of age.
Think and answer. 1. Which method of reproduction appeared later in living organisms (vegetative, sexual, asexual)? 2. How does reproduction of an organism differ from reproduction? 3. What stages of development does the embryo go through and what are their features? 4. What is the role of the placenta and umbilical cord? 5. What characterizes the structure and formation of a child at different periods of its development? 6. What role does labor education, physical development, and spiritual growth play in the formation of a young person?
Explain the meaning of the terms: zygote, blastula, gastrula, fetus, newborn, infancy and nursery period, placenta, uterus, oviduct, ovary, umbilical cord, egg, ovum, sperm.
Embryogenesis: Developmentembryo
Preschoolperioddevelopmentbaby
Agepeculiaritiesschoolage
How do children change from 11 to 16 years old?
Resources:
Anastasova L.P. and others. Man and the environment. Textbook for differentiated instruction 9th grade. Moscow "Enlightenment" 1997.320s
Presentation hosting
In humans, germ cells are formed in special organs - gonads (in the ovaries in women and in the testes in men).
The female reproductive cell - the egg - is haploid, large, round, immobile.
During the process of embryogenesis, about 400 thousand primary germ cells are formed in the female body; their reproduction stops at the time of birth and they turn into first-order oocytes. Each oocyte is surrounded by epithelial cells and forms an egg vesicle (follicle). Only a small portion of the oocytes in a woman's ovary mature and give rise to eggs. This process begins at the age of 12-13 and ends at the age of 50-53. As the oocyte grows, the follicular epithelium expands, a cavity with liquid appears in it - a Graaffian bubble. The rupture of a mature follicle and the release of an egg from the ovary is called ovulation. It occurs on average once every 29 days. Usually one egg cell matures alternately in one or the other ovary. The formation of a second-order oocyte occurs in the fallopian tube. Here the egg is fertilized by a sperm.
The male reproductive cell - sperm - is formed in the testes during the process of spermatogenesis. The nucleus with a haploid set of chromosomes is located in the head of the sperm. The formation of germ cells is influenced by the secretions of the pituitary gland, ovaries, testes and other endocrine glands.
During fertilization, the egg and sperm fuse to form a diploid zygote.
The process of fragmentation of the zygote occurs within 3-4 days, when the zygote moves along the fallopian tube to the uterus. The resulting blastomeres form morulu, and then a single-layer embryo - blastula; a cavity is distinguished in it - blastocoel and the wall - blastoderm. As a result of fragmentation of superficially located blastomeres, a membrane is formed that is involved in the nutrition of the embryo - trophoblast, and the central blastomeres form embryoblast, an embryo develops from it. Consequently, the resulting germinal vesicle includes a trophoblast surrounding the cavity with fluid, and an embryoblast - a germinal nodule lying in the cavity.
In the second week, gastrulation occurs and the trophoblast plunges into the uterine wall: in a seven-day embryo, the ectoderm forms the amniotic sac. From the embryo, which has the shape of a shield, cells move into the cavity of the blastula and fill it. Together with the trophoblast, these cells form chorion Subsequently, the embryonic membranes develop - amnion And yolk sac. The yolk sac functions as a hematopoietic organ. The primary urinary bladder is a derivative of the yolk sac. allantois. Subsequently, the amnion grows over the embryo and forms a watery membrane of the fetus, protecting it from damage and creating a homogeneous liquid environment here. The part of the chorion facing the wall of the uterus has villi, grows into its tissue and forms the baby's place, or placenta, through which the fetus is nourished. The blood vessels of the fetus and mother intertwine in the placenta. Nutrients and oxygen are absorbed from the blood of the mother's body and waste products are released.
After the birth of a child, his body grows and develops until he is 20-23 years old. The development process is divided into four periods: 1) chest, during which the child eats a highly valuable product - mother's milk, containing all the necessary substances for development; 2) nursery - from one year to three years; 3) preschool - from three to seven years; 4) school - from seven to 17 years is the period of formation of the basic physical, mental and moral qualities of a person.
| Periods of development | Structural features | Physiological features | |
| Embryonic | Zygote | Fertilized egg. Carries a diploid set of chromosomes: one set is from the egg, the other is from the sperm. Each chromium pair is homologous | Fertilization occurs in the oviduct, where the sperm penetrates as a result of sexual intercourse. The oviduct connects the ovary (female reproductive gland) to the uterus, where further development of the embryo occurs |
| Blastula | The first stage of embryo development. Represents a single-layer multicellular vesicle | Formed in the oviduct as a result of fragmentation (mitotic division without subsequent cell growth) of the zygote | |
| Gastrula | The second stage of embryo development. having two germ layers: ectoderm and endoderm; then the mesoderm appears. All organ systems are formed from these three leaves. | The blastula moves into the uterus and penetrates its wall, after which a gastrula is formed from it. On the side of the gastrula where it is in contact with the wall of the uterus, embryonic membranes (placenta, bladder) are formed, on the opposite side - the embryo | |
| Fetus | Goes through all stages of embryonic development, similar to the stages of development of vertebrates; the bladder is filled with watery liquid, the placenta is embedded in the walls of the uterus with its villi; The umbilical cord connects the placenta to the fetus. The fetus has one circulation | Features of embryonic development (gill slits, tail), as well as hair, indicate the common origin of all chordates and confirm the position of the biogenetic law. By 9 months, the fetus completely acquires all the features of the human body. Developing in an aquatic environment, it is protected from shock and moves freely. He receives oxygen through the placenta via the umbilical vein. and nutrients, venous blood returns to the mother’s body through the umbilical artery |
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| Postpartum | Newborn | A newborn has a disproportionate body structure - a very large head and short legs and arms. The bones of the skull are not fused, between them there are skin films - fontanelles; pelvic bones unfused, spine without bends | Unfused bones overlap each other, reducing the volume of the head and body, which helps the birth of a child. When the umbilical cord is ligated, an excess of CO2 is created in the blood, which has a humoral effect on the respiratory center of the medulla oblongata and as a result the first reflex movement occurs - a cry and a breath. Then the next innate reflex appears - sucking |
| Infant (up to 12 months) | The child masters movements - raises his head, lies on his stomach, stands up - this contributes to the formation of curves of the spine: cervical, thoracic, lumbar. Baby teeth appear | The child’s muscles are formed, movements become varied, the skeleton is strengthened, and the need to walk appears. In the first period - feeding with breast milk, containing all the necessary nutrients, then supplementing with food containing vitamins. Higher nervous activity develops - the first words are spoken | |
| Nursery (1-3 years) | The child's body proportions change: the head becomes relatively smaller, the limbs lengthen. The brain develops more pronounced sulci and convolutions | An independent organism, it switches to eating regular food. The fontanelles in the skull are overgrown. Expressed emotions, articulate speech. Constant medical supervision and care for a fragile body is required | |
| Preschool (3-7 years old) | Baby teeth are replaced by permanent ones. Differences in the cells of the cerebral cortex are clearly revealed | Concerted movements. Speech associated with thinking. Conditioned reflex centers of speech and writing are formed | |
| School (7-17 years old) | Enhanced development of the musculoskeletal system, enhanced growth of the body, which ends by the age of 20-25. After 10 years, the pelvic bones fuse. In accordance with the structural features of the body, childhood, adolescence and youth periods of development are distinguished | At the age of 13-15 years, restructuring of the body begins in connection with puberty, the activity and structure of the cerebral cortex, and the functions of the endocrine glands change. This causes psychological (predominance of excitation over inhibition), physiological (menstrual cycle) and physical changes in the body. Secondary sexual characteristics appear: in girls, the body shape and timbre of the voice changes; in boys - body proportions, physical development increases, the voice breaks, facial hair appears. However, full formation ends by the age of 20-25. | |