Lecture 2-Physical Development and Biological change Flashcards
2 causes of development
- nature (gessell): Maturation-natural growth that unfolds in a fixed sequence independently of the environment.
- nurture (watson): Behaviourism-all behaviour is learned.
3 stages of pre natal development
germinal stage-fertilisation to 2 weeks:placenta
embryonic stage-2 weeks to 2 months:development of organs
foetal stage- 2 months to 9 months: 6 mos-eyelids open/foetus breathe / 8 mod-respond to light and touch learning occurs - HABITUATION
teratogens
- external substances that can penetrate placenta, resulting in spontaneous abortion or birth defects
- most likely to affect development when ingested during the period of rapid organ development known as CRITICAL PERIOD
FASD Foetal Alcohol Spectrum Disorders
- congenital problems associated with excessive alcohol use.
- infants-microcephaly, heart defects, irritability, hyperactivity, delayed cognitive and motor development
- common cause of intellectual disability
Examples of teratogens
- FASD (small eyes, philtrum, upper thin lips)
- Thalidomide
Newborn vision
-blurry (20/300)
-able to see large objects at close range
-stare longest at objects that have qualities and contours like human face
DEPTH PERCEPTION-develops at 7 months of age
Newborn hearing
- hearing is poor
- soft tones
- turn head towards sounds
- notice difference between tones one note apart on musical scale
- hearing attuned to SOUNDS OF SPEECH-preference for rising tones (women/children), high pitched, exaggerated, expressive speech
- does not develop adult like acuity until childhood.
Newborn smell
- similar to adults although less acute
- preferences: flower smells, smell of own mother or other mothers
- dislike ammonia smells
2 Principles guide for motor development
Cephalocaudal trend-head to foot direction
Proximodistal trend-centre outward direction of motor development (gain control over trunk before extremities)
Reflexes
- involuntary, unlearned motor behaviours that occur in response to external stimuli
- disappears at approximately 3 months of age, when neurological development is sufficiently mature to allow voluntary control of muscles.
examples of reflexes
palmar grasp
rooting
moro (startle reflex)
Development of motor norms
lifts head- 2 weeks rolls over-2.5 months sits-5.5 months stands alone-11.5 months walks alone-12.5 months
physical development in childhood
- girls and boys grow at similar rates during childhood
- growth trajectory for girls and boys then SHIFTS with PRE-PUBERTAL GROWTH SPURT in girls
Growth trends in middle childhood: Brain
- approaches full adult size early in middle childhood.
- age 6: brain has 90% adult volume.
- 10% occurs in middle childhood: contribute to PLASCTICITY
Obesity
-has significant social and psychological consequences
-50% of children who are obese at age of 6 are obese in adolescence and early childhood
FAT PREJUDICE: slimmer children more desirable as playmates
OVERWEIGHT CHILDREN: fewer invitations, less popular in classrooms, less happy with lives,less confident
Physical growth at adolescence
- biological event of puberty elicits neurological, cognitive and social changes of adolescence
- pubertal changes: only universal changes of adolescence
Puberty
- growth of the reproductive organs
- changes in body fat/muscle distribution
- onset of menstruation in women -MENARCHE
- first ejaculation of sperm in males-SPERMARCHE
- pubertal changes take from 2 years to 4 years to complete
Secular trend: Tanner (1968)-puberty to begin at earlier ages than in previous generations
- decrease in the age of menarche
- age at menarche has dropped by 3 to 4 months every ten years
- increase in growth rate
- increase in height and weight
Reasons for the secular trend
- improved nutrition
- better childcare and knowledge of childhood illnesses
- improved sanitation
Body image
- self evaluation that the individual makes his own body
- multidimensional construct comprising evaluation of: weight, muscularity, body strength and condition, shape and size of various bodily parts
2 components of self evaluation
perceptual
affective
Female body image
female body image: based on the amount of body fat/consistently worse than males body image
male body image: based on the amount of body fat and muscularity/previously more positive, but rates of eating disorders rising.
middle adulthood
-loss of sensory sharpness: hearing loss/less sensitive to light/increased farsightedness
Changes in middle adulthood in women
- menopause: hot flashes, dizziness, headache, weight gain
- increased risk for heart disease
- decreases in bone mass
- osteoporotic changes
5 theories on physical changes of old age
- evolutionary theory
- cellular clock theory
- free-radical theory
- mitochondrial theory
- hormonal stress theory
cellular clock theory (hayflick, 1977)
- cells divide max of 75 to 80 times
- as humans age, cells become less capable of dividing
- limit to human lifespan 120 to 125 years, depends on TELOMERES
Telomeres
- DNA sequences that cap chromosomes
- each time a cell divides, telomeres become shorter
- after 70 to 80 replications, telomeres are so reduced, cell can no longer reproduced:CELL DEATH
Free radical theory
- free radical increase associated with over eating
- low calorie diet that maintains nutrients reduces oxidative damage caused by free radicals
mitochondrial theory
- minute bodies within cells that supply energy for cell function, growth and repair
- decay in mitochondria-ageing
- decay in mitochondria caused by: oxidative damage by free radicals
- loss of critical micronutrients supplied by cell.
