Chapter 3

Cephalocaudal Pattern

• the sequence in which the fastest growth in the human body occurs at the top, with the head

• Physical growth in size, weight, and feature differentiation gradually works its way down from the top to the bottom (for example, neck, shoulders, middle trunk, and so on). T

Proximodistal Pattern

• the growth sequence that starts at the center of the body and moves toward the extremities

• An example is the early maturation of muscular control of the trunk and arms, compared with that of the hands and fingers.

• Further, infants use the whole hand as a unit before they can control several fingers

Growth Patterns

• it often is not smooth and continuous but rather is episodic, occurring in spurts

• In infancy, growth spurts may occur in a single day and alternate with long time frames characterized by little or no growth for days and weeks

Growth Trends in Infancy

• 20 inches long and weighs 7.5 lbs

• the fastest rate of growth

Growth Trends in Early Childhood

• slimmer stature

• lengthening of trunk

• decline in body fat

• growth here may vary a lot bc of genetics

Growth Trends in Middle and Late Childhood

• slow, constant growth

• average 2-3 inch growth, 5-7 lbs weight gain a year

• the calm before you hit puberty

Puberty

a brain-neuroendocrine process occurring primarily in early adolescence that provides stimulation for the rapid physical changes that take place during this period of development (Nguyen, 2019)

Order of Puberty Changes in Men

1. increase in penis and testicle size

2. appearance of straight pubic hair

3. minor voice change

4. first ejaculation (which usually occurs through masturbation or a wet dream)

5. appearance of curly pubic hair, onset of maximum growth in height and weight, growth of hair in armpits,

6. more detectable voice changes

7. growth of facial hair

Order of Puberty Changes in Women

1. breasts enlarge or pubic hair appears

2. hair appears in the armpits

3. the female grows in height and her hips become wider than her shoulders

4. Menarche

Menarche

• a girl’s first menstruation

• comes rather late in the pubertal cycle

• cycles initially may be irregular

Horomones

powerful chemical substances secreted by the endocrine glands and carried through the body by the bloodstream

Endocrine System

role in puberty involves the interaction of the hypothalamus, the pituitary gland, and the gonads

Hypothalamus

a structure in the brain, is involved with eating and sexual behavior

Pituitary Gland

• controls growth and regulates other glands such as the gonads

• sends a signal via gonadotropins to the appropriate gland to manufacture hormones

• through interaction with the hypothalamus the pituitary gland also secretes hormones that either directly lead to growth and skeletal maturation or produce growth effects through interaction with the thyroid gland, located at the base of the throat

Gonads

• the testes in males, the ovaries in females

Gonadotropins

• hormones that stimulate the testes or ovaries (the gonads)

Testosterone

• a hormone associated in boys with the development of genitals, increased height, and deepening of the voice

• present in pubescent boys and girls, just more in boys

• Males – development of genitals, increase in
  height, facial hair

• Females – body hair, oil production, muscle
  development, sex drive

Estradiol

a type of estrogen associated in girls with breast, uterine, and skeletal development

Estrogen

• Females – development of breasts, uterus, and
  skeletal changes

• Males – bone growth, body fat, libido, voice
  change

Timing of Puberty

• affected by nutrition, health, family stress, and other environmental factors

• some studies say ppl w higher BMI’s start puberty earlier

• For most boys, the pubertal sequence may begin as early as age 10 or as late as 13½, and it may end as early as age 13 or as late as 17

• For girls, menarche is considered within the normal range if it appears between the ages of 9 and 15

Gender Differences in the Timing of Puberty

• Girls tend to mature faster

• Girls who mature early suffer negative
  social/psychological effects

• Boys who mature early tend to benefit socially, while
  “late bloomers” suffer

Growth Trends in Early Adulthood

• age 18-39

• height remains mostly constant

• peak functioning of the body is the twenties (19-26)

• can begin to see signs of aging

  • wrinkles

  • joint pain

  • weight gain in abdomen

  • sagging chin and skin

Growth Trends in Middle Adulthood

• increased, but still gradual decline

• Physical Appearance:

  • start to lose height and many start to gain weight

  • skin loses plasticity (from loss of fat and collagen in underlying tissues)

Middle Adulthood Change in Strength, Joints, and Bones

• sarcopenia - age-related loss of lean muscle mass and strength

• sarcopenic obesity - reference to individuals who have sarcopenia and are obese

Middle Adulthood Change in Cardiovascular System

• Cardiovascular disease increases considerably in middle age

• Cholesterol comes in two forms: LDL (low-density lipoprotein) and HDL (high-density lipoprotein)

  • LDL is often referred to as “bad” cholesterol because when the level of LDL is too high, it sticks to the lining of blood vessels, a condition that can lead to arteriosclerosis

  • HDL is often referred to as “good” cholesterol because when it is high and LDL is low, the risk of cardiovascular disease decreases

Middle Adulthood Change in Lungs

• at about the age of 55, the proteins in lung tissue become less elastic

• This change, combined with a gradual stiffening of the chest wall, decreases the lungs’ capacity to shuttle oxygen from the air people breathe to the blood in their veins

Middle Adulthood Change in Sexuality

• Climacteric - the midlife transition when fertility declines

  • Menopause - the time in middle age, usually in the late forties or early fifties, when a woman has not had a menstrual period for a full year

  • Testosterone production begins to decline about 1 percent a year during middle adulthood, and this decline can reduce sexual drive (Hyde & others, 2012). Sperm count usually shows a slow decline, but men do not lose their fertility altogether.

Late Adulthood Change in Physical Appearance

• Increased changes

• Weight drops after 60 due to muscle
  loss

• Healthy lifestyle can prevent this

Late Adulthood Change in Circulatory Appearance

• increase in hypertension rates

  • heart attack

  • stroke

  • kidney disease

Frontal Lobe

voluntary movement, thinking, personality, emotion, memory, sustained attention, intentionality or purpose, self-control

Occipital Lobe

Vision

Temporal Lobe

hearing, language processing and production, and memory

Parietal Lobes

registering spatial location, special ability, focusing attention, and maintaining motor control

Neurons

nerve cells
that transmit and
process information

How Neurons Process Infromation

Basically, an axon sends electrical signals away from the central part of the neuron. At tiny gaps called synapses, the axon communicates with the dendrites of other neurons, which then pass the signals on. The communication in the synapse occurs through the release of chemical substances known as neurotransmitters

Myelination

• encasing a neuron in fat to increase
  speed and efficiency with which information travels

• important for brain functioning

Myelin Sheath

• the fatty substance that insulates the axon of the neuron

• controls how fast a neuron communicates

Synapse

gap between a sending and receiving neuron

Lateralization

• left

  • Speech and grammar

  • controls right side of the body, analytic reasoning, and language

• Right

  • humor and the use of metaphors depend

  • attention and emotion

  • ontrols left side of the
    body, special reasoning, emotional reasoning

This is called lateralization - specialization of function in one hemisphere of the cerebral cortex or the other

The Infant Brain

• Sensitive Period

• Synaptogenesis: growth of synapses in the
  brain

• Synaptic Pruning: removal of unnecessary
  synapses

  • Promote efficient processing

  • Environmentally influenced

• Plasticity: the brain can is changes by our
  experiences

  • Trauma and plasticity

  • Greatest plasticity during early development

Brain Development in Infancy and Childhood

• Brain triples in weight first two years of life

• Large degree of myelination

• Development of neural pathways

  • As we experience and learn

• Stimulating environment

  • Growth depends on what is being learned

The Brain and Neglect

• causes depressed brain activity

• some damage can be reversed if caught early

Brain Development in Adolescence

• Growth focused on efficiency

  • corpus callosum thickens

    • connects hemisphere

• Some areas have reached maturity

  • limbic system - emotions and rewards

    • amygdala

  • Dopamine

    • increased levels contribute to ward seeking

• Brain isn’t done yet:

  • prefrontal cortex - controls decision making and emotion

Corpus Callosum

where fibers connect the brain’s left and right hemispheres, thickens in adolescence, which improves adolescents’ ability to process information

Limbic System

which is the seat of emotions and where rewards are experienced, matures much earlier than the prefrontal cortex and is almost completely developed by early adolescence

Amygdala

A part of the brain’s limbic system that is the seat of emotions such as anger

Aging in the Adult Brain

• On average, the brain loses 5 to 10 percent of its weight between the ages of 20 and 90

  • number of synapses decreases, neurons shrink

  • increased decline in late adulthood

  • slower processing speed and memory

• decline

  • prefrontal cortex - working memory

  • acetycholine - memory, alzheimer’s

  • dopamine - parkinsons

• exercise, diet, and continued stimulation through challenging the brain can slow this

Free-Radical Theory

• build up of toxins and chemicals over time

  • metabolic processes produce unstable oxygen

  • oxygens pair inefficiently in the body

Cellular Clock Theory

Leonard Hayflick’s theory that the number of times human cells can divide is about 75 to 80. As we age, our cells become less able to divide

Mitochondrial Theory

The theory that aging is caused by the decay of the mitochondria, which are tiny cellular bodies that supply energy for cell function, growth, and repair.

Telomerase-Injection Theory

• the ends of DNA unravel as cells reproduce

  • eventually, new cells are unstable

  • cells cannot replicate and die

Sirtuins

A family of proteins that have been proposed as having important influences on longevity, mitochondrial functioning in energy, calorie restriction benefits, stress resistance, and cardiovascular functioning

mTOR Pathway

A cellular pathway that involves the regulation of growth and metabolism and has been proposed as a key aspect of longevity

Hormonal Stress Theory

The theory that aging in the body’s hormonal system can lower resistance to stress and increase the likelihood of disease.

Life Span maximum numbers of years an individual can live

about 120-125 years

Why do We Sleep?

• evolutionary - needed to protect themselves at night

• replenishes and rebuilds the brain and body, increases the production of proteins

• clears out waste in neural tissues

• essential to waste plasticity

Stages of Sleep

Sleep in Infancy

• ages 0-2 sleep 12.8 hours a day

  • newborns sleep 16-17 hours

REM Sleep

• rapid eye movement

• take up more time in infancy than any other point in the life span

• for adults, (and maybe babies, we don’t know) this is when they dream

SIDS (Sudden Infant Death Syndrome)

• a condition that occurs when infants stop breathing, usually during the night, and die suddenly without an apparent cause

• remains the highest cause of infant death in the United States

  • highest around 2-4 months

Causes of SIDS

• Many causes: Arrhythmias, low birth weight, temporary sleep
  apnea, abnormal brain stem functioning, exposure to
  cigarette smoke

• Biggest risk: sleeping on stomach and sleeping with parents

Sleep During Childhood

• 2-6: 11-13 hrs w a daytime nap

• 7-12: 10-11

• routine w good sleep hygiene probes brain to wind down and fall asleep quicker

Childhood Sleep Habits

• Good habits:

  • better attention, language abilities, social skills, peer acceptance, school performance

• Bad habits:

  • can contribute to ADHD

Sleep in Adolescence and Emerging Adulthood

• Most need 7-8 hours, but very few get this

• Poor sleep can lead to:

  • obesity

  • poor school performance

  • attention problems

  • caffeine use

  • anxiety

  • depression

Sleep in Adulthood

• 7 to 8 hours

  • Chronic sleep deprivation

    • Cardiovascular disease

    • Shortened life span

    • Impaired cognitive abilities

      
      

• Can be counted by:

  • Less caffeine, sleep aids

  • healthy weight

  • healthy diet

  • stay active!

The Effect of Marijuana on the Brain

• Impact on teenagers

  • Drug dependency (marijuana and other!)

  • Schizophrenia

  • Self-control

  • Decision making

  • Neurotransmitter disruption

• Impact on developing fetus

  • Emotional regulation

  • Susceptibility to addiction