Section 2.1 Physical development theories

a. Growth

Growth refers to the quantitative increase in size, height, weight, or volume of an individual or part of the body over time. It is a biological process that can be measured objectively and is most noticeable during childhood and adolescence. It is more rapid during infancy and adolescence and slows in middle childhood.

b. Motor Skill Development

•    Gross motor skills: involve large muscles (e.g., walking, running, jumping).

•    Fine motor skills: involve small muscles (e.g., grasping, writing, buttoning).

•    Development follows predictable patterns:

− Cephalocaudal: growth from head to toe.

− Proximodistal: growth from the center outward to extremities.

c. Brain and Nervous System Maturation

Maturation of the brain and nervous system refers to the gradual and orderly development of the brain, spinal cord, and nerves that control physical and cognitive functions (Paus, 2022). This process starts before birth and continues into early adulthood, supporting the development of motor skills, emotional regulation, learning, and behavior. The nervous system begins forming in the embryonic stage (about 3 weeks after conception). By birth, the baby has most of the neurons they will ever have, but many are not yet connected.

Authors such as Benes, Turtle, Khan, and Farol (1994) explain that myelination which begins before birth continues into the early 20s, especially in the brain’s frontal lobes (responsible for decision-making and planning). Myelin is a fatty substance that covers nerve fibers, helping messages travel quickly. The brain grows rapidly in the first few years of life by age 5, it’s about 95% of adult size (Giedd,1999). Adolescence brings another wave of growth and reorganization, especially in areas involved in impulse control and judgment.

d. Puberty and Hormonal Changes

Puberty is the period of rapid physical, hormonal, and emotional changes during which a child’s body matures into an adult body capable of reproduction. It usually occurs between the ages of 8–13 for girls and 9–14 for boys, but the timing can vary (Rogol, Roemmich, & Clark, 2002). Puberty is triggered by the activation of the endocrine system, particularly the hypothalamic pituitary gonadal (HPG) axis. The hypothalamus signals the pituitary gland to release LH (Luteinizing hormone) and FSH (Follicle Stimulating Hormone). These hormones stimulate the gonads (ovaries in girls, testes in boys) to produce sex hormones: (1) estrogen in girls and (2) testosterone in boys. These hormones drive the physical and reproductive changes of puberty (Abreu, & Kaiser, 2016).