Postembryonic development. Puberty

The postembryonic stage of a child’s development includes the following periods:

• newborns – the first 4 weeks after birth;
• chest – from the 4th week to 1 year;
• nursery – from 1 to 3 years;
• preschool – from 3 to 6 years old;
• school – from 6-7 to 16-17 years old.

From the moment of birth to maturity, the growth and development of the body is uneven. The periods of accelerated growth and development alternate with their slowdown. Growth and development are most intense in the first year of life and during puberty. Before puberty, body length increases mainly due to the growth of the legs, and after puberty, due to the trunk. In the process of growth and development, the proportions of the human body also change, which is clearly visible in the ratio of the size of the head and body.

Puberty boys

The first signs of puberty in a boy are an increase in the size of the testes and external genital organs. In the testes, sperm cells begin to mature and the male sex hormone is produced, under the influence of which male secondary sexual characteristics are formed:

• hairiness appears in the lower abdomen (on the pubis), in the armpits and on the face;
• the skeleton is growing rapidly (the annual increase in the growth of boys can reach 10 cm) and muscles; the shoulders expand, and the pelvis remains narrow (the figure takes on a male silhouette);
• the voice becomes lower – “breaks” (this is due to the fact that the cartilage of the larynx and the length of the vocal cords increase and change);
• under the influence of the sex hormone, the secretion of the skin glands increases, especially on the face and back (acne may appear, which usually disappears by the age of 25-30);
• about 14 years old, sperm begins to be released, the involuntary release of which most often occurs during sleep and is called wet dreams (wet dreams indicate that the testes are developing normally and the boy becomes a young man).

The production of sperm and sex hormones in the male body lasts up to 50–55 years, then gradually stops.

Puberty girls

In girls, by the age of 10, the release of pituitary hormones increases, which cause ovarian growth. In the ovaries, female sex hormones begin to be produced, under the influence of which female secondary sexual characteristics develop:

• mammary gland;
• pubic and armpit hair;
• under the influence of the sex hormone, the secretion of the skin glands increases, especially on the face and back (acne may appear, which usually disappears by the age of 25-30);
• the skeleton grows and develops intensively: the bones of the pelvis expand, the shoulders remain narrow (the figure acquires a female silhouette);
• at the age of 12-14, menstruation appears – a sign of the maturation of eggs in the ovarian follicles. At first, menstrual cycles are irregular, and a regular menstrual cycle is usually established after 2–3 years.

At the age of 45–55 years, a woman’s menstrual cycles stop – menopause occurs.

Characteristics of adolescence

Teenagers are not children, but they are not adults either. During adolescence (girls from 12 to 15 years old, boys – from 13 to 16 years old), changes occur in the body that prepare a person’s sexual, physical and mental maturity.

Adolescents at this time need good nutrition, with a sufficient content of proteins, fats, carbohydrates, mineral salts, vitamins.

During puberty, there is a mutual interest of the sexes, the desire to please each other. At the same time, the increased secretion of sex hormones causes increased emotionality, unexplained anxiety, confusion. The teenager becomes conflicted and cocky. At this age, self-education is of great importance.

Physical and mental work, sports, social work contribute to the harmonious development of a teenager, the upbringing of healthy, strong and spiritually rich people.

In adolescence, smoking and drinking alcohol are especially dangerous, which delay mental and physical development.

Smoking disrupts the activity of the nervous system, heart, blood vessels, liver, reproductive system; the skin turns yellow or turns pale, loses its elasticity and freshness, teeth turn yellow, bad breath appears.

Drinking alcohol weakens a person’s control over their behavior, dulls shame, a sense of disgust and self-safety.

Since the reproductive system is actively developing in adolescence, smoking, alcohol and drug use can affect the ability to have healthy offspring in the future.