This document summarizes biological and health changes that occur throughout the human lifespan from infancy to late adulthood. It discusses physical, brain, hormonal, and sleep changes in each life stage including infancy, childhood, puberty, early adulthood, middle adulthood and late adulthood. Major changes include rapid growth and brain development in infancy, puberty bringing sexual maturation in adolescence, peak physical performance in early adulthood followed by gradual physical and cognitive decline in later life stages.

1. Biological and Health Changes
Across Lifespan
By Andrea Romo, Joslynn Silvers, Farrah Shattuck, and Steven Pauley

2.  Human beings go through many changes throughout their lifespan. Including
physical changes, development of the brain, hormonal changes, and even
changes in sleep patterns.

3. Major Changes Through Lifespan
 Infancy
 Childhood
 Puberty
 Early Adulthood
 Middle Adulthood
 Late adulthood

4. Infancy
 This is the stage were we grow more rapidly
 Infants double their newborn weight approximately by 4 months of age and
triple it by their first year.
 By age 2, they reach 1/5 of their adult weight

5. The Brain in Infancy
 Brain development occurs extensively during prenatal period. Brain
development is substantial during infancy and later.
 At birth, the newborn’s brain is 25% of its adult brain. 75% by their second
birthday
 Two key developments during the first two years involve the myelin sheath
and dendrite connections.
 Visual myelination is completed in the first six months
 Auditory myelination is completed until 4-5 years of age
 During their first year of life, infants develop an ability to regulate their
physiological states (sleep) and gain more control over their reflexes
 Children who grow in a deprived environment may have depresses brain
activity

6. Sleep in Infancy
 A study shows that children who did most of their sleeping at night, engaged
in higher level of executive function at age 4 (Bernier others, 2013).
 The link between sleep and cognitive functioning likely occurs because of
sleep’s role I brain maturation and memory consolidation, which may improve
daytime alertness and learning.
 Poor sleep is associated with language delays

7. Early childhood
 As preschoolers grow older, the percentage in height and weight decreases
with each additional year
 Typically, girls have more fatty tissue while boys have more muscle tissue
 The main factors that contribute to children's height and weight are genetic
influences, ethnic origin, and nutrition.

8. Middle and Late childhood
 Slow, consistent growth
 Children grown an average of 2 to 3 inches per year
 Gain 5-7 pounds a year
 Muscle mass and strength increase as “baby fat” decreases
 Changes in proportions are the most pronounced during this stage. Head and
waist circumference and leg length decrease in relation to body height

9. The Brain in Childhood
 The brain and their nervous system continue developing through childhood.
These changes enable children to plan their actions, attend stimuli more
effective, and make considerably strides in language development
 During childhood, the brain and the head grow more rapidly than any other
body part.
 Myelination is important in the maturation of a number of abilities in
children. ei. Hand-eye coordination, and focusing attention
 The anatomical changes between 3-15 are dramatic.
 The prefrontal cortex continues to increase- cognitive control. Controlling
attention, reducing interfering thoughts, inhibiting motor actions, and
cognitive flexibility

10. Puberty
 Puberty is a brain-neuroendocrine process occurring primarily in early
adolescence that provides stimulation for rapid physical changes that occur
during this period of development

11. Male Pubertal Characteristics
 Increase in penis and testicle size
 Appearance of straight pubic hair
 Minor voice change
 First ejaculation
 Appeareance of curly pubic hair
 Onset of maximum weight and height
 Growth of hair in armpits
 More detectable voice changes
 Growth of facial hair
 Peak pubertal average age is at 13 ½ years old

12. Female Pubertal Characteristics
 Breast enlargement
 Appearance of pubic hair
 Armpit hair growth
 Grows in height and hips get wider than shoulders
 Girls get their first menstruation, or, menarche
 Peak pubertal average age is at 11 ½ years old

13. Hormonal Changes in Puberty
 Behind the changes in characteristics mentioned in the past two slides, is a
flood of hormones, powerful chemical substances secreted by the endocrine
glands and carried through the body by the bloodstream
 Males: produce testosterone, hormone associated with the development of
genitals, increased height and deepening of the voice
 Females: produce, estradiol, type of estrogen associated with breast, uterine,
and skeletal development

14. The Brain in Adolescence
 The corpus collosum which connects the brain’s left and right hemispheres
thickens, which improves the ability to process information
 The limbic system, which is the seat of emotions and where rewards are
experienced, is almost completely matured by early adolescence
 The prefrontal cortex is not completely developed, to the point where
sometimes they cannot control their strong emotions, which can be shown
through rebelliousness or behaviors

15. Adolescents’ Health
 Adolescence is a critical juncture for adopting behaviors that affect health
 Social contexts, family, peers, schools, neighborhoods, and culture influence
adolescents’ health
 Smoking cigarettes, using marihuana, getting into fights, substance abuse,
and engaging in sexual activity are risk factors in adolescence
 Peer pressure can initiate the above mentioned.

16. Early Adulthood
 Physical changes during these years may be subtle, but they do continue
 Height remains constant
 Peak functioning of body’s joints
 Reach a peak of muscle tone and strength in their late teens and twenties
 Reach peak levels of physical performance before the age of thirty
 These attributes mentioned above start to decline at age thirty

17. Middle Adulthood
 Physical appearance:
 individuals lose height and some gain weight. Decrease in height is due to bone
loss in the vertebrae
 Skin begins to wrinkle and sag because of fat and collagen loss in underlaying
tissues
 Aging spots appear because of production of pigmentation
 Hair thins and grays because of slower replacement rate and decline of melanin
production
 Strength, joints, and bones:
 Sarcopenia or, age related loss of lean muscle mass and strength
 Muscle loss occurs at 1-2 % loss a year
 Maximum bone density occurs late to mid thirties and declines from there. It
begins slowly but accelerates in the fifties

18.  Cardiovascular system: cardiovascular disease increases in middle age
 Cholesterol levels in the blood increase
 Blood pressure rises in forties and fifties. High blood pressure is linked with a
increased rate of mortality
 Women go through menopause. Their blood pressure rises sharply and stays
above men’s
 Lungs: at about age 55, the the proteins in lung tissue become less elastic,
this combined with gradual stiffening of the chest wall, decreases the lungs’
capacity of oxygen inhalation
 Sexuality: fertility declines
 Women go through menopause usually in their late forties or early fifties. This
is when women do not get a menstrual period for over a year.
 In menopause, production of estrogen by the ovaries declines dramatically
and produces uncomfortable symptoms. Such as hot flashes, fatigue, nausea,
and rapid heart beat.
 Men go through a modest decline in their sexual hormone level and activity

19. Late Adulthood
 Late adulthood brings an increased risk of physical disability and variable
rates in decline in functioning
 Physical appearance: the changes in middle adulthood are more noticeable.
More wrinkles, sagging, aging spots.
 By age 60, weight drops
 Circulatory system: hypertension becomes more problematic and likelihood
of stroke increases
 Rise in blood pressure with age can be linked to illness, obesity, and kidney
disease

20. The Adapting Brain
 The human brain has a remarkable repair capacity
 Humans can go through neurogenesis, or the generation of new neurons
 Changes in lateralization, or specialization of function in one hemisphere of
the brain, may provide one type of adaptation in aging adults
 Using both hemispheres may improve the cognitive function of older adults

21. Health and Aging
 Chronic Disorders are characterized by a slow onset and long duration. They
become more common in late adulthood
 Common chronic disorders for women are: arthritis, hypertension, hearing
impairments, and heart disease
 Common chronic disorders for males are: higher incidence of fatal chronic
conditions
 These can be prevented or reduced by living a healthy, active, stress reduced
lifestyle

22. References
 Santrock, J. W. (2016) A topical approach to life-span development (8th ed.).
New York, NY: McGraw-Hill Education