Growth:
The process of physical, physiological, and behavioural changes that result in an increase in the size, complexity, and capability of an organism.
Phases of Human Development:
- Infancy: It extends from birth to 10 months of age. At birth, the head is about one-fourth of the whole body. After birth, the arms grow faster than the legs. The infant is a vibrant and seemingly unlimited source of energy.
- Childhood: It extends from 10 months to about 13 years of age. The legs attain their proportionate sUe only after 10 years. The growth rate increases gradually.
- Adolescence: It extends from 13 years to 18 years of age. There is enhanced activity of growth hormones. The growth rate is high and attains a maximum. Due to the increase in sex hormones secondary sex characters are established in males and females.
- Adulthood: It extends from 18 years to 25 years of age. After the age of 18 years, the growth rate gets reduced and stops altogether after the age of 22 – 22 years. Secretion of sex hormones is diminished and the function of STH is almost closed.
- Senescence or late adulthood: It extends from 25 years of age onwards. After 25 years of age, many organs show a gradual decline in their functional activities. Many organs may even regress in size. As the organism grows older the power of metabolism gradually declines.
