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Development After Birth

Psych 125 Human Development Christopher Gade Office: 1031-G Office hours: Tu 12-1:30 and by apt. Email: gadecj@gmail.com Class: T 1:30-4:20 Room 2210. Development After Birth. When newborns enter the world, they differ from their adult counterparts in a number of ways. Small size

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Development After Birth

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  1. Psych 125Human DevelopmentChristopher GadeOffice: 1031-GOffice hours: Tu 12-1:30 and by apt.Email: gadecj@gmail.comClass: T 1:30-4:20 Room 2210

  2. Development After Birth • When newborns enter the world, they differ from their adult counterparts in a number of ways. • Small size • Imbalanced dimensions (head size, extremities) • Underdevelopment (brain, muscle, bone) • Different chemistry (hormones, neurotransmitters) • Little ability to interact with their environment

  3. Biology-Based Growth in Life • Each of us grows in slightly different ways, but all of us follow a fairly similar path. Moreover, we develop biologically in a number of ways. • Physical development (size, proportion, content) • Brain and nervous system development (size, structure, and function)

  4. Basics at Birth • Most newborns (95% of them born in the US) are born between 18-22 inches long and 5 ½ to 10 pounds. • Most exceptions to this are due to external factors • Mother’s diet • video • Mother’s smoking • Genetic problems • Prenatal problems • Premature births

  5. Tracking Physical Growth • Infancy (0-2 years) – weight rapidly increases (2.5 – 5x), height increases (1.5 – 2x), and muscle mass begins to increase • Early childhood (2-6) – weight and height increase, but slowly. Differentiation between individuals becomes very noticeable (fat, muscle, height, weight) • Exceptional differences in size are related to experience • Diet (malnourishment and overeating) • Growth hormone deficiency – the absence of deficiency of a growth hormone produced in the pituitary gland • Genetic, structural, stress related • Prenatal experience (smoking, stress, other teratogens) • Physical ailment (sickness, injury)

  6. More on GHD

  7. Tracking Physical Growth • Middle and late childhood (6-11) – “dormancy” in physical growth (1-2 inches and 5-7 pounds per year). Muscle mass, bone development, coordination, and better proportions mark this stage of physical development.

  8. Tracking Physical Growth • Puberty (9/11 – 15/17) – massive amounts of physical change occur due to a rush of hormones – chemical substances secreted by the hypothalamus and the pituitary gland. • Reproductive growth (physical and capability growth) • Height and weight growth (men = muscle, women = fat) • Physical changes in voice (men), breast size, hair, skin, and skeletal system • Women = earlier and slower; estradiol (more overall increase) and testosterone (2x) • Men = later; testosterone (8x) and extradiol (small increase) • Note: the onset of puberty has been linked to social and nutritional factors (diet, stress, etc.)

  9. The Social Impact of Early Maturation • Precocious puberty – the very early onset and rapid progression of puberty • Occurs much more often in girls than boys (10x) • Early development impact girls negatively at the time • Riskier behaviors, more emotional and social problems • And impacts girls negatively in the future • Poorer school performance, life choices that are similar to older peers, more time with older peers, more emotional problems, more drug and alcohol problems • These same impacts don’t appear to occur for boys

  10. Tracking Physical Growth • Post-puberty to adulthood to elderly age • We grow until our early to mid twenties • At around thirty our bodies begin to slowly decline • More fat collects in specific areas • We begin to shrink (men = 1 inch from 25 to 75, women 2 inches from 25 to 75) • We lose fat under our skin (wrinkles) • Our skin loses its elasticity and becomes colored from experience • Our muscle mass (sarcopenia) and elasticity also decline • Out bone strength and density decrease

  11. The Later Years of Change • From the age of 50 on, the decline of the physical body becomes much more rapid • Females experience menopause • Biological change – reproductive abilities, bone density, muscle density • Chemical change – estrogen (causes hot flashes, fatigue, nausea, and other side effects) • Physical appearance changes more rapidly • Physical ailments become much more common (cholesterol, circulatory, muscular, skeletal, lung related) • Note: Many of these changes can be offset to an extent with both cognitive and physical exercise

  12. Now onto another type of change • Now that we’ve discussed how we progress throughout life physically… • In this next section, we’ll discuss how we progress in our brain and nervous system.

  13. Brain and Nervous System Development • At birth, our brains have several important characteristics to them. • Structure – areas of the brain that are associated with specific functions • Lateralization – halves of the brain that are associate with specific functions • Neural plasticity – the ability for the brain to adjust to physical and environmental changes

  14. More on Neural Plasticity • At birth, our brain has nearly as many neurons (60-100 billion) as we have in adulthood. • The difference is, very few synapses between the neurons are formed yet.

  15. What causes this growth in connections? • Experience based formations • Language example (more activity in specific areas) • Deprivation example (less activity) • Problem and growth related rerouting • Early damage example (right hemisphere took over control of language)

  16. Other Growth-Related Changes in Our Nervous System • Myelination – the covering of the dendrites of neuron cells with fat cells that speeds up the communication process between neurons • In class example

  17. Growth During Childhood • Synaptic “pruning” – the reduction in synapses that begins at about 1 year of age • Lobe development • 3-5 frontal lobe growth (planning and organization) • 5-15 parietal and temporal lobe (speech/language, coordination, and spatial abilities)

  18. Growth During Adolescence • Development of the amydala and limbic system occur rapidly at this stage • Greater range of emotions • Stronger emotions • Development of the prefrontal lobe is very slow (doesn’t complete until around 25) • Control of planning and though • Self-regulation and self-preservation

  19. The Decline in Adulthood • As we age, our brains slowly begin to lose weight (5-10% from ages 20 to 90) • Loss of synapses through continued “pruning” • Loss of myelination • Possible loss of neurons • Basic cell death • Neurogenesis alternative • Early findings of neurogenesis in the hippocampus and olfactory bulb • New attempts to prove that with exercise and challenge, neurogenesis can occur throughout the brain

  20. A Note on Brain Development and Experience/Exercise • Numerous studies have shown that exercise and experience both play a role in the successful function of the brain • Video • Greater synapse density • Greater blood flow to cells • Possible increase in neurogenesis

  21. That’s it for today… • Reviewing: • In this class we addressed how our bodies develop physically • We also discussed how our brains developed physically • Foreshadowing: • In the next class, we look at the development of health and health related problems

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