Post-embryonic development

The time allocated to a living organism for the realization of its genetic program is usually called postembryonic or postnatal (for a person) period of development. It begins with the moment of birth and ends with death, and duration depends on species characteristics, lifestyle, external circumstances and other factors.

In our smaller brothers and in humans, the period of postembryonic development consists of three stages:

1. The juvenile. This is the first stage - it is determined by the time from birth to puberty, accompanied by active growth, the final formation of all organs and systems, and can proceed in different ways. In particular, two types of postembryonic development are distinguished: direct and indirect. If a newborn individual is similar to an adult by the external signs and features of the organization of physiological processes, then this is a direct postembryonic development. In the case of indirect development, the organism is subject to metamorphosis.
2. A puberty, or a period of puberty. This is one of the longest stages of postembryonic development, when the body is able to reproduce.
3. Aging. The natural final stage of the life cycle, which ends with death or forced death.

Features of the postembryonic period of human development

The organs and systems of the little man are formed in the womb of the mother, here the child receives genetic material, which is the fundamental factor of its development. The intrauterine period has its own stages, each of which is characterized by a number of changes.

For example, in the second month of pregnancy the embryo becomes like an adult, although its size does not exceed 3 mm, and existence outside the mother's body is not possible. By the time of birth the weight of the baby reaches 3-4 kg, height is 45-55 cm, and the systems that ensure the vital activity of the body are already ready for independent functioning.

At the sight of a newborn baby, it becomes obvious that the path of his post-embryonic development will be direct. Since the adult differs from the adult only in the proportions of the body and the immaturity of some systems.

The postnatal period of the development of man, as a rational being, has been thoroughly studied, and is divided into:

1. The newborn period is ten days after birth. At this time, the baby spends most of the day in a dream, and for full growth and development he needs breast milk.
2. Breast period - from 10 days to a year. During this span, the crumb makes a huge leap in its mental and physical development. By the end of the first year of life, most of the children are already confidently standing on their feet, eating a variety of food, the first syllables utter.
3. Early childhood is 1-3 years. In children, coordination of movements improves, they are able to clearly and consistently set out thoughts and requirements, constantly replenish the vocabulary, are actively interested in the surrounding world.
4. The first childhood is 4-7 years. "Radio Kryuchochki" broadcasts around the clock - the child will not rest until he receives an answer to the question asked, and the latter arise a lot.
5. The second childhood is 8-12 years. Children at this age qualitatively changing the picture of the worldview, there is a final formation of motor activity.
6. The adolescent period is 13-16 years. Sex hormones begin to be produced, in connection with which, there are significant changes in the child's body, both physical and psycho-emotional.
7. The youth period is 17-21 years. The condition of a young organism is almost identical to that of an adult.
8. The mature period is 22-60 years. At this age, all systems are formed, growth stops, and the person finally enters the reproductive phase.
9. The elderly age is 61-74 years. Characterized by a number of external signs that indicate the wilting of the body.
10. The senile period is 75-90 years.
11. Long-livers - over 90 years.