Description of Physical Development
- Before a human is born, an embryo is created when a male sperm cell fertilizes a woman's egg. The two fuse together and form a zygote, which develops into an embryo after a period of three weeks, and becomes a fetus in the eighth week of the gestational phase. During the prenatal state of development, the embryo begins to develop limbs and major organs.
- When a human is born, he will go through several developmental stages before becoming adolescents. During the neonate, infant and toddler stages, a baby will learn motor skills that will allow him to hold his head up by himself, crawl, pull himself up and eventually walk. The brain development of a young child will enable him to communicate with sounds and then words.
A play-age child will have developed endocrine systems that secrete hormones and enable him to quickly grow. As a result, his head is no longer one of the most predominate body parts, and his limbs can now extend past the head when the arms are lifted. - When a child reaches adolescence, or puberty, his primary reproductive organs have begun to mature. Other physical developments during adolescence include the growth of body hair on males and females, facial hair on males, and changes in the shape of a female's breasts and hips. Teens will also experience growth spurts and weight gain.
- Adulthood begins when a person is in their early 20s. During this time, new muscles are still developing. When a person is almost 30 years old, new muscle formation ceases and the metabolism slows, causing potential weight gain.
When an adult reaches 30 to 40 years of age, differences in physical and mental status become noticeable. Due to changes in the eyes, an adult may find the need to use glasses. The lung's capacity will begin to decrease and, as a result, breathing rates will increase. The skin will lose elasticity throughout adulthood and cause the formation of wrinkles.
When a woman is in her 40s or 50s she will go through menopause, which concludes her capacity to reproduce. As result of the lost estrogen in her body, a woman will have higher testosterone levels that will cause unwanted facial hair to grow. - An adults is considered a "senior" once he is 55 to 60 years old. During this time, the bones in the body begin to lose mass and strength, and vision and hearing loss becomes more pronounced. As neurons in the brain begin die to at a faster rate, mental functions also decrease. As overall body functions begin to slow down and deteriorate, a human will have undergone all stages of physical development by the time they die.