Physical Development in Humans
i. The Newly Born Child
The weight of a newborn depends on its genetic factors as well as on the nourishment provided during pregnancy. The average normal weight of newborn babies can range from 5 to 8 pounds. After birth the nutrition source of the baby changes but it is still dependent on its mother for its food, the baby learns to feed in absence of the placenta. Food is extremely important for supporting growth and other metabolic functions.
A newborn’s gastrointestinal tract or the digestive system as a whole has not been developed enough to process complex solid food items so it derives its nutrition from its mother’s milk. The milk of the mother is sufficient for the baby, being enriched with nutrients and antibodies required for continual growth.
As a newborn is still in the developing phase it is vulnerable to external factors in the environment like electromagnetic radiation, exposure to which can detrimentally affect its growth. Exposure to babies to electromagnetic radiation in recent times has increased due to scientific technologies in the field of wireless communications like EMF.
Even the baby monitors possess a threat as when they are on “standby” or “on” mode emit high-frequency radiations. Research indicates that exposure to even low-frequency magnetic fields may lead to the development of leukemia in children and the growth of tumors that are not detectable until adolescence.
A newborn’s nervous system is still developing and is thus, vulnerable to radio frequencies (RF) that can implicit adverse effects. Penetration of these frequencies occurs more in the babies than in an adult’s case. They will experience greater effects due to a longer lifetime exposure that will act cumulatively.
ii. The Toddler
The toddler can now feed on solid food, can crawl and walk and perform other basic functions, they observe and start to learn and develop. The child is less dependent on the mother for procuring its food at this the endocrine system is developing and starts to secrete hormones.
They show developmental patterns of accelerated growth which will progress till early childhood. The hormones synthesized will be in accordance with the genetics of the toddler and will determine the growth and height of the developing child. According to the rule of the thumb, the height seen in the toddler at 2 is proportional to its final height excluding unusual environmental factors.
iii. Puberty and Adolescence
Steady growth patterns can be seen from early childhood to adolescence after puberty starts. During the period of puberty, sexual characteristics like secondary sexual characters and maturation of gametes occur that allow them to become sexually active for reproduction.
a) Puberty in Females
Girls on average reach puberty earlier and the estrogen levels increase as they are synthesized and released by the ovaries. This hormone acts on the mammary gland tissues to enlarge them. At this point, there is an inclination of the growth phase and this acceleration continues in the teenage years due to the growth hormone. Approximately there is an increase of 20 centimeters in height during this phase.
The endometrial wall or lining of the uterus thickens as the menstrual cycle is initiated due and periodical monthly changes are triggered due to estrogen. This lining sloughs off along with some blood causing bleeding and is called periods, this happens every 28 days. Menarche signifies female fertility and the ability to reproduce.
b) Puberty in Males
Boys attain puberty later than girls but their puberty phase lasts longer and growth spurts occur during this period as in girls. This growth spurt occurs due to the release of the hormone testosterone by the testes in males. Males are taller than females on average as this hormone is more effective in initiating growth spurts.
They also exhibit secondary sex traits due to prolonged testosterone secretion. These characters include deepening of their voice, increased body hair, and development of muscularity. Sperm production is initiated initially by the secretion of testosterone making the males fertile for reproduction.
When puberty stops at the end of adolescence the person has attained maturity. True growth is seen as an increase in the number of cells ceases and further only regenerative growth is seen. Menopause occurs around the 50s in women as no more eggs are released by the ovaries. At the time of birth, a female baby may have around 1,00,000 follicles, which degenerate and decline to only 100,000 by puberty.
With the advance in medical science, technology, and better living conditions people age and live longer. Research studies are focusing on the degenerative aspect of aging to understand the concepts behind this process and how they can slow them and increase longevity. As people age, our systems become less efficient to maintain homeostasis leading to degeneration and ultimately death.
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