Exam 1 Flashcards
Three Stages of Prenatal Development
I. Germinal
II. Embryonic
III. Fetal
Duration of prenatal development stages
I. Germinal (0-2 weeks)
II. Embryonic (3-8 weeks)
III. Fetal (9 weeks-birth)
What happens during the duration the germinal stage?
- Zygote is not susceptible to environmental factors
- Fertilization and formation of zygote
- Cell division as zygote falls fallopian tubes
- Stage ends with implantation in the uterine wall
What happens during the duration the embryonic stage?
- Cell migration
(newly formed cells move from the place division occurs to the final destination) - Cell differentiation
(sections of genes (DNA) create proteins that determine what cell type it will become) - Cell “death”
(genetically programmed death of cells (Apoptosis)
(necrosis - cell death caused by trauma)
What stage is the time of the most sensitive period?
Embryonic stage
- A sensitive period
- All major body structures and organ systems are forming, most sensitive to teratogens
What is the support system that develops along the embryo?
- Amniotic sac (protective buffer)
- Placenta (exchange center)
- Umbilical cord
Development occurs from?
From head down (Cephalocaudal)
From center out (Proximodistal)
What happens during the fetal stage?
- Swallowing
- Breathing movements
Fetal movement
5-10 weeks or so: constant movement
10-20 weeks or so: more periodic
20 weeks: 3/4 of time in quiet, active sleep states (REM sleep)
Teratogens
An agent that alters the growth or structure of the developing embryo or fetus; it can cause damage or death during prenatal development
Types of environmental agents
Presence: of an agent that is not typically part of normal development (e.g. drugs, lead, alcohol)
Absence or lack: of environmental input needed for typical development (e.g. folic acid, nutrition)
What are some of the factors that can influence the degree of harm a teratogen will cause?
- Timing of exposure
- Dose-response relation: the amount of exposure
- Individual differences in susceptibility
What are some methodological complications? (In relation to teratogens)
- Sleeper-effects
- Invisible pollutants
- Cumulative risk
What methods are used to examine teratogens on developmental trajectories?
- Observational studies: prospective and retrospective
- Experimental animal studies
What is the most sensitive period of a developing fetus? Why?
Embryonic stage
It is a critical period because it’s the formation of internal and external structures
Thalidomide and importance?
- Medicine used to treat nausea in pregnancy
- Infants were born with limb abnormalities and malformations of organs
- Sensitive period (24-36 after fertilization)
Fetal alcohol syndrome (FASD)
- Fetus is exposed to large amounts of alcohol over a long period of time
Criteria for FASD diagnosis
- Alcohol exposure
- Growth
- Facial characteristics
- Cognition
Birth canal vs cesarean section
- Being squeezed through birth canal reduces size of head which stimulates hormone production that helps breathing after birth
- Forces amniotic fluid from lungs
- C-section is critical to save lives
Preterm births (less than 37/8 months, low bw 5.5 lb)
- Maternal stress
- Diet
- Health
- Drug abuse
Why do so many babies die in the richest country in the world?
- Disparities due to inequality
- Poverty—no health insurance, limited access to good prenatal care
- Other developed countries (with better rankings) typically have
government-sponsored health care
Infant sleep?
- Babies sleep 2x more than adults
- Pattern of REM and non-REM sleep changes
Why is there so much REM in babies?
Auto-stimulation theory - high activity in visual areas of the brain during REM
- Their high level of brain activity during REM makes up for the lack of visual stimulation for typical newborns and helps develop visual stimuli while babies sleep
Sudden Infant Death Syndrome (SIDS)
- Infants stop breathing during sleep without any obvious cause
- Majority of cases are between 2-4 months
- Causes still unclear
To prevent sudden infant death
- Parents shouldn’t smoke around baby!
- On firm mattress, no pillow, bumpers,
excess blankets (use sleep sack, or tuck in
firmly) - Keep infants cool, not overly warm
- Share a room, not a bed
- Breastfeedyndrome
Crying characteristics
- Peak crying is the first 3 months
- Peak time is late afternoon/evening
- Early crying is an indicator of discomfort or attempt to communicate
How to soothe the crying?
- Moderately intense and continuous or repetitive stimulation
- Swaddling—wrap tightly, restrict limb
movement - Distracting—works temporarily
- Touch/carrying
- Ride in car or stroller or baby swing
- Taste of something sweet*
Colic babies
- Excessive crying for no apparent reason
- To diagnose 3hrs/a day, 3 days/week, 3 weeks in duration
- Peaks at 6 weeks and resolves between 12-16 weeks
Infant feeding benefits
- Carbohydrates, enzymes, and hormones that promote intestinal
health/biochemical balance– breast milk is an immune booster - Lower rates of SIDS, infections, asthma, childhood leukemia, high blood
pressure, obesity, and diabetes - Positive effects of cognitive development
- Bonding, attachment
- For mom: reduces risk of breast and ovarian cancer
The nueron
- Basic unit of information processing in the brain
- Cells specialized for sending and receiving messages between brain and body
Parts of the neuron
- Soma
- Dendrites
- Axon
Neurons make up the grey matter of the brain
Soma
- Also cell body, integrates incoming and outgoing signals
Dendrites
- Receive incoming signals and relays it to soma
Axon
- Carries outgoing information to other neurons, muscles, or glands
Arborization of dendrites
- Development of new dendrite branches
- Increases capacity to form connections with other neurons
- Continues to grow across first few years of life
Supporting cells (glial cells) functions
- Glue: hold the neurons in place
- Nourishment: convert glucose into lactate that feeds the
neurons - Development: guide newly created neurons to their
proper spot - Protection/Increase Speed: Glial cells that accomplish
this are made of a fatty substance known as myelin
Myelination
- Myelin formed by glial cells
- Neural signals = fast and efficient
- Myelin growth begins before birth but continues as late as age 25
Neurogenesis
- Production of neurons through cell division
- Rapid neurogenesis during 3rd and 4th week of prenatal life
“Use ir or lose it”
- Synapses that are used are strengthened
- Synapses that are not used are eliminated (pruning)
Synaptogenesis
- Formation of synapses between
neurons in early brain development
Pruning
- The number of synapse drop
significantly (up to 50%) between the
ages of 2 and 10
Why does the brain develop this way?
- Genes are setting the possibility for the specificity of connections
- Experience shows what connections are functional as they get used
Experience-expectant plasticity
- Brain expects input from the environment, receives after birth
- Like vision development, social/language development
- Involves synapse and pruning
Experience-dependant plasticity
- Happens throughout life
- Relates to all learning
- Individual experience
Genotype
- Genetic material an individual inherits
Phenotype
- Observable expression of the genotype (body characteristics and behavior)
Genetics and environment IQ
- Variations in IQ is more likely
due to genetics in high SES
contexts - Variations in IQ is more likely
due to shared environment in
low SES contexts - As family income increases,
the influence of the
environment decreases
and the influence of the
genes increase
