1. Chapter 5 The Physical Self

2. The neuron
Dendrites
Cell Body
Axon
Synapse
Neurotransmitters

3. Figure 5-2 Parts of a neuron
Figure 5-2 Parts of a neuron. (a) Although neurons differ in size and function, they all contain three main parts: the dendrites, which receive messages from adjacent neurons; the cell body; and the axon, which sends messages across the synapse to other neurons. (b) The formation of dendrites leading to new connections among existing neurons, as well as the myelination of neural pathways, accounts for much of the increase in brain weight during a baby’s first two years.
Figure 5-2

4. Plasticity
Responsiveness to experiences
Can be negative
Vulnerable to damage
Environmental deprivation
Can be positive
Aids in recovery from from injury
Can compensate for each other
Can benefit from stimulation
Allows for adaptability

5. Brain Development
Critical period: late prenatal & early infancy
Lateralization (at birth)
Left hemisphere
Analytic reasoning, language
Right hemisphere
Understanding spatial information
Visual-motor information
Corpus callosum connects the two

6. Brain Development
Never truly complete
Changes occur across lifespan
Growth spurts in infancy, childhood and adolescence
Full adult weight by about age 16
Processing speed increases in adolescence
Myelination continues into adulthood

7. Brain Development
The Aging Brain
Gradual and mild degeneration
Elderly adults
5-30% fewer neurons than younger adult
Greater loss in sensory-motor areas
Plasticity still possible
Main result of age is slower processing

8. Principles of Growth
Procession of growth is orderly
Cephalocaudal: from head, downward
Proximodistal: from the center, outwards
Orthogenic: from global, undifferentiated to specialized

9. Infant Physical Behavior
Developmental norms (see Table 5.5 )
Average age of mastery
Gross before fine motor skills
Crawling at 7–10 months
Walking at about 1 year
Study of “walkers” (Siegel & Burton, 1999)
Infants not using walkers sat up, crawled, and walked earlier
Need sensory feedback I.e.,to see feet

10. Physical Behavior
Manipulating Objects
Grasping reflex disappears: 2-4 mo
Pincer grasp by 6 months
Motor Skills
Rhythmic Stereotypies
Rocking, bouncing, mouthing objects, banging arms and legs
Precede a skill then disappear

12. Adolescence Growth spurt triggered by hormones
Peak in height: age 12/girls, 14/boys
Menarche: average age 12 1/2
Earlier in countries with good nutrition, longer life, and higher literacy rates
Maturation different by ethnicity
AA and MA girls earlier than White
Semenarche: average age 13
emission of seminal fluid

13. Rates of Development
Genes set the process in motion
Hormones responsible for changes
Environment also
Secular trend: better nutrition
Earlier maturation,larger body size
Poorly nourished/mature later
Heavy & tall/mature earlier
Regular strenuous exercise/later

14. Psychological Implications
Girls become concerned w/appearance
Individual reactions vary widely
Negative views about menstruation
May contribute to poor body images
Boys likely to welcome the changes
Family relations remain important
Distance & conflict with parents
Usually about only minor issues

15. Early vs. Late Development
Early/males: advantage
More positive reactions from others
Late/males: disadvantage
More behavior & adjustment problems
Early/females: disadvantage
Subject of ridicule,lower self esteem
Older peer group = problems
Late/ females: academic advantages
Differences tend to fade with time

16. Physical Behavior
Dramatic physical growth overall
Boys continue to improve
Girls tend to level off or decline
Not totally explained by biology
Gender role socialization important
Gender performance gap has narrowed
E.g., track, swimming, cycling records

17. The Adult
Minor changes in the 20s & 30s
Noticeable by the 40s
Wrinkles, gray hair, weight gain
In the 60s: Weight, muscle, bone loss
Osteoporosis in older women
Fair, light frame, smokers
Calcium, exercise, HRT
Osteoarthritis: joint deterioration

18. Functioning and Health
Most systems show decline with age
Heart & lung capacity
Temperature control
Immune system and strength
Reserve capacity
On average, older people are less fit than younger BUT not all
Physically active remain fit

19. Slowing Down
Balance difficulty affects the ability to walk, stand, sit, and turn
Older people with strong muscles and good cardiovascular capacity can walk briskly
Central change is slowing in the CNS
Increased RT
Novel/complex tasks more difficult
*physically fit older people have quicker RT

20. Disease, Disuse, and Abuse
Birren (1963) study of men aged 65-91
Healthy older same as younger
Conclusion: Aging itself has little effect on physical and psychological functioning
Disuse: “Use it or loose it!”
Includes mental exercise
Abuse contributes to decline
Alcohol, high-fat diet, smoking