Summary of Growth Across Life Span
Studies how humans learn, mature, and adapt from infancy to adulthood to the elderly phases of life. Some areas of focus include physical, cognitive, social, intellectual, perceptual, personality, and emotional growth.
Prenatal
Rate of growth: More rapid than any other stage of the life span.
Brain and Nervous system: Increase in number and size of nerve cells to attain 25% adult brain weight and size at birth.
Height: From one cell to an average of 50cm at birth.
Weight: Increases from one cell to an average of 3kg of body tissue at birth. Especially large weight gain in the 2-3 months before birth as a result of fat deposit
Muscle: Most cells present at birth but they have high water and connective tissue content.
Infancy
Rate of growth: Very rapid in the first year and then slower in the second.
Brain and Nervous system: Extensive and rapid growth.
Height: Rapid gain in first 3 months, which can be equal to the total gain from 2-3 years. May reach 25% of adult height.
Weight: Birth weight doubled by 6 months and then trebled by 21 months. The gain in the second year is slower, often half that of the first year. Weight gain is mostly from fat tissue.
Muscle: Accounts for 25% of the weight. Size is increasing through growth in length, breadth, and thickness.
Childhood
Rate of growth: Slows down markedly in preparation for adolescence.
Brain and Nervous system: Slows down, 75% of an adult brain at 3, and the brain reaches maximum size by 10.
Height: Slows down but shows a greater increase than weight.
Weight: Slows down. Increases are now mainly due to bone and muscle tissue.
Muscle: Develop extensively and water content increases. There is no difference between the strength of males and females.
Adolescence
Rate of growth: Very rapid, but not quite as rapid as infancy.
Brain and Nervous system: Nerve connections and associations continue to build up. Myelination continues.
Height: Rapid skeletal growth leads to an average gain of 20cm in males and 16cm in females.
Weight: Increase is the result of bone and muscle tissue.
Muscle: Differences in strength and muscle/fat ratio of males and females become evident.
Adulthood
Rate of growth: Only growth in cell replacement for maintenance of existing tissues.
Brain and Nervous system: No likely change to capacity.
Height: Maybe an increase of 1-2cm but generally finished.
Weight: Refer to man and woman and Healthy Weight Range. Increases generally due to fat deposits.
Muscle: Represents 40% total weight and maximum strength at 25-30.
Late adulthood
Rate of growth: Negative because cell loss is greater than cell reproduction. Functions are slowed but not lost.
Brain and Nervous system: 65-70% have lost 20% of nerve cells that were present at birth. This leads to less acuity but not capacity.
Height: May appear to decrease due to change in posture through loss of strength of postural muscles.
Weight: Energy balance determines weight although some weight loss can occur through the loss of lean tissue.
Muscle: Reduce in size through loss of fibers as protein is replaced with fat. This leads to some loss of strength.
December 23, 2022
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