Ch. 2
Friday, August 22, 2008
10:03 AM
Changing ideas over time
Preformationism-
Life starts with the new individual already preformed, compsed of a full set of tiny parts
Epigenesis- (aristotle)
An emergence of new structures and functions during development
Embryology-
Study of prenatal development
Conception (just know general overview)
Gametes (germ cells)
Reproductive cells that only have half of the genetic material compared to other cells in the body
23 chromosomes in each
Reduction allows for reproduction (need 23 pairs)
Egg (mother) and sperm (father)
Egg moves from the ovaries through the fallopian tube to the uterus
If sperm are present, conception can take place
Union of egg and sperm (gametes) results in 23 pairs of chromosomes
Sex differennces begin at conception
Approximately 120 to 150 males are conceived for every 100 females
The sperm bearing the y chromosome are lighter and swim faster to the egg than those bearing an x chromosome
However, male embryos are miscarried at higher rates than female
Boys are more vulnerable to developmental disorders
Males are also more vulnerable to illness through out life
The zygote
Def: fertilized egg
Contains a full complemet of human material, half from each parent
3 periods of prenatal dev
Germinal
Conception to 2 weeks
Lasts until the zygote becomes implanted in the uterine wall
Rapid cell division takes place
Embryonic
3 to 8 weeks after conception
Major development occurs in all the organs and systems of the body
Fetal
9 weeks after conception to birth
Continued development of physical structures and rapid growth of the body
Inc levels of behavior, sensory exp, and learning
The cells
4 major developmental processes transform a zygote in an ambryo and then a fetus
Cell division
Rapidly
Cell migrations
Occurs during embryonic period,
Cells move to another part of fetus
Move from inside brain out
Cell differentiation
Any cells can form into any other type of cells
Selective death of certain cells (apoptosis)
Could be born with webbed feet if does not occur
Hormones
Testosterone = male genetalia
Twins
Identical twins
Splitting in half of the cell mass, same genes
Fraternal
Two eggs are released into the fallopian tube
Not genetically same
Embryo
After implantations, inner cell mass becomes embryo and rest of cells develop into support system
Neural becomes brain and spinal cord
Support system includes:
Placenta: permits exchange of materials between bloodstream of fetus and that of mother
Umbilical cord: tube that contains the blood vessels that travel from the placenta to the developing organism and back again
Protecting the fetus
The placental membrane is a barrier against some, but not all toxins and infectious agents
The amniotic sac: a membrane filled with fluid in which the fetus floats, which provides a protective buffer for fetus
**Just need a basic understanding of development**
Embryo at 4 weeks
Prenatal development from the 4th week on is cephalocaudal
Inside out development - cells go from the inside towards outside
Development towards head happens earlier than development towards the extermities
Face development from 5.5 and 8 weeks
Cleft pallet can occur at this time
Fetus at 9 weeks
Head is half of the body length
Internal organs are beginning to be present
Sexual differentiation starts
Starts to make small movements
Fetus at 11 weeks
Lobes of brain differentiate
Heart is visible
Fetus at 16 weeks
Body starts to catch up to head
Makes movements mom can feel
Sex of baby can be determined
Fetus at 18 weeks
Thumb sucking
Rapid growth
Fetus at 20 weeks
Raises eyebrows and makes facial expressions
Fetus at 28 weeks
Can give birth and have a chance to survive
The fetus: an active contributor to its own development
Swallowing amniotic fluid
Promotes the normal development of the palate
Aids in the maturation of the digestive system
Movement of the chest wall and pulling in and expelling small amounts of amniotic fluid
Helps the respiratory system become functional
Fetal rest activity cycles
Become stable during the second half of pregnancy
Circadian rhythms are also present
Near the end of pregnancy, fetus's sleep and wake states are similar to newborns
Sensation
Sensory structures are present relatively early in prenatal development
Play a vital role in fetal development and learning
Tactile stimulation
Sounds
Moms voice most prevelant
Picks up info about mother voice
Visual experience is negligible
Least developed when baby is born
Tastes and smells the amniotic fluid
Fetal Learning
At 32 weeks gestation, the fetus dec responses to repeated or continued stimulations, a simple form of learning called habituation
Newborn infants have been shown to recognize rhymes and stories presented before birth
Newborns also prefer smells, tastes, and sound patterns that are familiar because of prenatal exposure
Hazards to prenatal development
Miscarriage
Spontaneous abortion
45% or more of conceptions result in very early miscarriages
15-50% of pregnancies of which women are aware are miscarried
Usually have severe defects
Teratogens
Def: environmental agents that have the potential to cause harm during prenatal development
Timing is a crucial factor
Sensitive period
Thalidomide- moms took it to ease morning sickness. Didn’t know it caused birth defects
Dose response relations
The more used, the more harm it causes
Individual differences influence the effects of teratogens
Sleeper Effects
Don’t see anything thing wrong with baby, but could effect 20 years down the road
Include legal as well as illegal substances
Fetal alcohol syndrome (FAS)
Associated with mental retardation, facial deformity, and other problems
Cigarettes smoking during pregnancy is linked to retarded growth and low birth weight
Has been linked to sudden infant death syndrome (SIDS), although the ultimate causes of SIDS are still unknown
Happens between 2-6 months
Higher risk with multiple births
Higher in winter months
Various things to help prevent
Get prenatal care
See doctor
Eat well
No drugs, alcohol
Wait till older to have baby
Wait at least one year to have next child
Breast feed
Maternal factors
Age - young or older mothers have more of a risk
Nutrition - need good nutrition
Disease - disease may have an effect on the fetus
Emotional state - mothers who are more depressed and higher anxiety tend to have kids with more problems
Birth Experience
Oxytocin
Released and helps facilitates birth milk
Three stages
Contractions and dilation
Birth of baby
Delivery of placenta
Cultural variations exist in the birthing experience
Neonatal assessment: APGAR
Take tests 1 and 5 minutes after born
7 or above: good
Below 3: not good
Can get score between 0 and 2 on each part
Appearance - skin color
Pulse - heart rate
Want it to be above 100
Grimace - reflex irritability
Screams when you poke it with things, want your baby to be upset
Activity - muscle tone
Wants your baby to be moving around when it is born
Respiration - breathing
Needs to be breathing on its own
The Newborn infant
State of Arousal
Interacting with environment
State: infants level of arousal and engagement in the environment
Deep sleep to intense activity
Important for newborn to explore
Crying
Why do babies cry?
Very early on, it’s the way they tell you something is wrong
Later on, can display frustration
Type of cry babies exhibit change over time
Effective soothing techniques?
Burp, change diaper, feed, swaddling (only with very wrong babies)
Colic
Crying for no apparent reason
Infant Mortality
Death during the first year after birth
African american infants are more than twice as likely to die before their first birthday as euro american babies
Poverty and lack of health insurance
Low birth weight infants
Infants weighing less than 5.5 lbs are considered to be of Low birth weight (LBW)
Premature
LBW infants bron at or before 35 weeks after conception
Small for gestation age (SGA)
Birth weight is substantially less than the norm for their gestational age
Risk factors
Tend to occur together in the world
A negative outcome is more likely when there are multiple risk factors
Developmental resilience
Successful development in the face of multiple developmental hazards