There are the following ages:
1. Child aged from birth to the start of the period of puberty (12-13 years).
2. Adolescence (puberty) - from 12-13 to 16 years of age in girls, and from 13-14 to 17-18 years in boys. This age is characterized by a sharp increase in body length with annual increase of 5-6 see To 15 years (compared with a newborn) growth tripled and reaches an average of 158 cm boys and 156 cm in girls. Body weight respectively 48 and 49 kg To 14-15 years appear all permanent teeth, except for wisdom teeth. During this period, there comes one of the most important age crises - pubertal, based on the change in the functions of the endocrine system of the body, which leads to the appearance of secondary sexual characteristics, the onset of menstruation in girls, and the occurrence of wet dreams boys. General metabolism in the body becomes intense, but unsustainable, labile. The psychic life of a teenager is very complex and volatile and demands from teachers, doctors and parents great tact and perseverance.
3. Youth age is from 16 to 25 years for women and from 17 to 26 years for men. Characterized by slower growth, the average annual increase of 0.5, see In this age usually appear wisdom teeth.
4. Adult age is from 25 to 40 years for women and from 26 to 45 years for men. The period of relative stabilization morphological and metabolic processes.
5. Ripe age from 40 till 55 years for women and from 45 to 60 years for men. In this period comes the second most important age crisis - menopausal, especially clearly manifested in women. Menopause is associated with the extinction of the sex glands and reconstruction of a number of hormonal systems of the body. Mental sphere and metabolism characterized by significant lability.
6. Old age is between 55 and 75 years for women and from 60 to 75 years for men.
7. Senile age over 75 years for women and men. Begins to develop common involution of the body.
Sometimes offer to allocate a special age of centenarians for people 90 years and older.
An accurate determination of the age is important in the clinic and forensic practice. About age can be judged on the basis of data on height, weight, number of teeth, skin condition. With age, a person's face wrinkles. To 20 years - frontal and naso-lip, to 25 years at the outer edges of the eye behind the ears, a 30-year - infraorbital, by 40 - cervical, for 55 years - in the lobes of the ears, arms, chin. However, all these criteria are very relative.
A more accurate method of establishing age is determination (x-ray) of the so-called bone age. The basis for determining it are regularities in the ossification of the skeletonassociated with age periods. For example, the point of ossification in the distal epiphysis of the radial bone appear in 12-14 months. in girls, and in 16-18 months. in boys. Sinology in the distal epiphysis elbow bones respectively 19 and 20 years. As a rule, to determine bone age use the image brush and distal bones of the forearm. Knowing the time of appearance of the points of ossification and synostosis, with high degree of accuracy to establish the age of a person.
Ages of children. For the period of childhood characterized by constant development and growth of child organism. Between different stages of development no strict face.
Children age precedes the period of intrauterine development, which distinguish the stage of embryonic development (first 3 months). and the stage of placental development (from 3rd to 9th month).
Extrauterine period of development is divided into several periods: 1) a pregnancy, continuing to 4 weeks of life; 2) maternal age, lasting from 4 weeks up to 1 year; 3) predostavleny, or nursery,from 1 to 3 years; 4) pre-school (period kindergarten) - from 3 to 7 years; 5) early school - from 7 to 12 years; 6) the senior school (adolescent, or puberty) - from 12 to 18 years (see above).
The neonatal period is characterized by incomplete development of all organs and systems. During this period, an adaptation of a child's organism to the conditions of external environment. Insufficient functional capacity of the various agencies is the reason for the development of a number of disorders, where it is difficult to distinguish between physiological and pathological conditions (physiological jaundice and albuminuria, physiological weight loss and others). Newborn extremely susceptible to coccal infection that requires a maximum of asepsis in the care of the child of that age (see the Newborn).
Chest age. For infancy characterized by the intensity of the growth and development of the child's body, which results in relatively greater need for high-calorie foods and requires proper nutrition. In violation of the quality and quantity of food possible eating disorders and digestion. Because of the relative functional weakness of the digestive system, the child feeds mainly dairy foods. In this period, the child is helpless, and requires special care.

The infant is formed first signal system. Children begin to learn things and persons are guided in the environment.
The rapid exhaustion of the Central nervous system. requires a large amount of hours of sleep and correct alternation of sleep and wakefulness.
The weakness of immunobiological defense mechanisms makes the children of the first months of life are more prone septic processes. In 2-5 months. the child is most vulnerable to infection due to lower passive and lack of active development of acquired immunity. During infancy is typical manifestation of constitutional anomalies, often exudative catarrhal diathesis (see the baby).
Predostavleny age in their biological characteristics has common features with infants and preschool age. By the end of the first year, especially after two years of hard develops it. In this age requires appropriate institutional arrangements that ensure the correct mode, education, adequate rest and further development of the child. In predostawlena age , the incidence of acute infections on the rise is mainly due to insufficient production of active immunity. This requires timely immunization of the child, as well as events that protect the baby from infection.
Preschool age is characterized by high mobility of the child's activity. Children are much more widely included in sporting activities.
In this period of childhood is especially important to correctly organize outdoor games, manual labor, and so on, During the elaboration of the day, especially the organization of walking, we must remember that the child is tired very fast in a slow stop walking. At preschool age frequent household and street injury; significantly increases the incidence of acute infections.
Younger school age is characterized by increased development of muscles, but the child's growth somewhat slowed down. Child develops at school and lives of his interests. Physical education should be organized so that they child was not tired, and contributed to improving exchange processes and functions of all body systems.
When significant school stress, improper organization sleep and rest may develop neurotic reactions. For younger school age high incidence of acute infections appear diseases, rare in predostawlena age (rheumatism, functional cardiovascular disorders, etc.).
Senior school age. In the physiological relationship is characterized by the maturation of the sex glands. Hormones sexual glands dramatically change the course of all life processes and influence on the functional state of the nervous system. In adolescents undergo a number of changes in the autonomic nervous system (instability heartbeat, dizziness , and so on).
There are also roughness of mood, irritability, fatigue. In adolescence gradually smoothed out and disappear morphological and physiological characteristics that distinguish children from adults. The disease is clinically traits adults. Cm. also the weight of the body.