Week 3 Flashcards
Humans are… (chromosomes)
diploid - each cell has 2 copies of each chromosome
How many chromosomes in the complete human genome?
complete genome has 23 pairs of chromosomes (46) - 23 from mom and 23 from dad
Why arent all children with same parents identical?
Meiosis - The process by which sex cells—eggs and sperm—are produced - that are unique - crossing over creates uniqueness
Which chromosome goes into which cell is random
Functions of meiosis
Shuffling of genetic content
Reducing genetic content
Mother produces 1 egg and father produces 4 sperm during meiosis
What happens in meiosis 1? What is the unique process
- 2 homologus pairs separate and migrate to two different cells
- Cell division when the original cell punches closed and splits in the middle - separating the cells
RESULT: two haploid daughter cells
Crossover - pair of homologous chromosomes pair up and exchange sections of DNA
Get a unique chromosome that has never existed before
Break at some random (but exactly the same point) and switch
What happens during meiosis II?
- Four daughter cells created from the two intermediate daughter cells
- Each cell splits in half resulting in a chromatid (one half of the symmetric chromosome) - Each of the four daughter cells has one chromatid which is ready to pair with the homologous chromatid that is introduced as a result of mating
RESULT: sex cell- egg or sperm with 23 chromosomes
Donor insemination
Donor semen is introduced into the female reproductive system
Intrauterine inesemination - semen injected into the uterus - does not have to travel through the mucus plug in the cervix
Use ultrasound imaging to place sperm in the best location to increase odds
IVF
Both sperm and eggs removed and introduced in the laboratory
Conception happens in the lab and the conceptus is placed in the uterus after a few days
8 mil babies born through IVF
Parents of children conceived via fertility methods were warmer, more responsive to their children and more emotionally involved, spent more time interacting - at 6 years
No difference at 12 years
zygote
Fertilized egg
beginning of prenatal period which typically lasts 38 weeks and is divided into 3 stages
Germinal Period
- Period of rapid cell division
1. Cells double every 12 hours - zygote travels from fallopian tube to the uterus
2. Zygote stage lasts for about 4 days until it develops into a hollow sphere of 100 cells - blastocyst - specialization begins (already has some structure and specialization - 3 layers - outer- hair skin, middle- skeleton, inner, internal organs) - Estimated that 40% of blastocysts do not proceed to the next stage
3. Germinal period ends when the blastocyst implants in the uterine wall - a week to 12 days after conception - Burys in uterine wall and opens up the mother’s blood vessels - access to blood supply - use nutrients in bloodstream and introduce hormones - end menstrual cycling
Pregnancy tests taken before implantation will read negative
End - blastocyst is less than a millimeter
blastocyst - specialization
3 layers -
outer- hair skin,
middle- skeleton,
inner, internal organs
The Embryonic Period - 2mm to 3cm
Begins once the blastocyst has completely implanted in the uterine wall - embryo - finds a blood vessel and opens the blood vessel - access to nutrients and o2 in bloodstream
3-8th week after conception -differentiation, specialization and growth
Embryo consists of 3 concentric layers
Ectoderm - will become hair, skin, sensory organs, eyes and ears, nervous system
Mesoderm - becomes muscles bones and circulatory system
Endoderm - digestive system and lungs
When does CNS start developing (embryonic period)
develops early from the end of the second week after conception - early in the 6th week
At what point in the embryonic period does the embryo have a basic body plan?
4 weeks after conception - embryo has a basic body plan - arm and leg buds - body is curved tightly like a shrimp
Face has 4 folds of tissue that will become facial features - primitive heart that beats and circulates blood
cephalocaudal - and when?
After 4th week - prenatal development is cephalocaudal - features near the head develop sooner than the rest of the body
When does facial development occur in the embryonic period
Facial development - 5 & 8th weeks
By the end of the 8th week -human like face with eyes, ears, mouth and nose
What is developed by the 8th week?
What is the status of movement
arms legs and fingers, toes developed, heart and circulatory system circulate the nutrients via the placenta and umbilical cord, digestive system developed, lungs and respiratory formed , kidneys-
baby is moving but movements are uncoordinated and jerky - not felt by mother
What does the amniotic sac do
Embryo rests in an environment designed to provide it with nutrients, remove waste and protect it from injury - lives inside the amniotic sac which is filled with amniotic fluid - protect from impact and temperature changes
What is the purpose of the umbilical cord
umbilical cord brings in fresh blood with oxygen and nutrients and removes blood high in co2 and waste.
Placenta
a highly vascularized spongy organ through which oxygen and nutrients are delivered to the fetus and carbon dioxide and waste are removed
Placenta - mother or baby?
Classic view - structure that the mother and fetus build together - original site of maternal nurturance
Reality - placenta develops with the embryo - embryo’s DNA
Structure designed to be parasitic - invades the uterine wall, bores into blood vessels and reconfigures them so they cannot constrict - mother cannot resist sharing nutrients with the fetus without reducing her own nutrients
Fetus raises mother’s blood pressure and blood sugar
Parental Investment based on relationship
Mother would like to invest in developing fetus - opportunity for genetic representation but only to an extent. Also wants to recover from the pregnancy with enough health and resources to support future pregnancies
Father - if long term partner - interests aligned but if pregnancy is short-term - all investment into child none into mother
- Blood pressure and blood glucose is higher - baby takes as much as they can get - may not be related to siblings
- Epigenome may be different from father - creating a placenta thats more invested in - status of relationship has a physiological impact on the sperm can epigenetically modify their DNA
The fetal period
Weeks nine - end (38) - growth and development
Fetus starts weighing an ounce
9 Weeks milestones
IOS DEGN
All internal organs are present but still developing
Sexual differentiation has started
External genitalia - weeks 7-12
Fingers toes and nails by the 4th month
12 WEEKS -
FT ESM
Fetus can form a fist, wiggle toes, suck thumb
Will respond to external stimulation - touch and noise
Fourth month - still enough room to swim, kick and turnabout
- Movement increases in the second half of pregnancy
16 WEEKS
S 2 M
Fetus will swallow amniotic fluid - kidneys working and the kidneys begin to produce urine - excreted into the amniotic sac
fetus may weigh 200g
mother can feel movement- Fluttering
20 WEEKS
I 8 MH
Inhales amniotic fluid as practice breathing - lungs start working - can smell it
From week 20 on fetus will gain 8 pounds
Maturation of the nervous, respiratory and digestive systems take place at this point
20-28 - hair eyebrows and eyelashes develop and skin thickens
28 WEEKs
EAST
Fetus may be well-developed enough to survive on its own - potentially viable
- Critical factors to survival - lungs ability to exchange co2 for oxygen, stomach digest food, brain’s ability to control
breathing,swallowing, body temp
Born this early - need to be protected against temp changes - lack layer of fat that develops in the 8th month
Eyes open and auditory system functions - brain development is similar to a newborn
Antibodies
Mother contributes disease fighting antibodies - tailored to diseases that mother has encountered - protect new born until they can produce their own antibodies at 6m
Last Month
Quiet sleep periods or rem slee
Monozygotic twins
What makes twinning more likely?
When does zygote divide?
How often?
Is it heritable?
one zygote - identical genomes - identical twins
Single zygote divides within the first few days of conception identical genomes
research with animals has found factors in embryonic development that make such twinning more likely (e.g., temperature, oxygen levels, and the age of the ovum when fertilized).
1 in 285 births.
Not heritable, does not vary across ethinic groups, no known variables that predict
Sharing placenta (chorion) and sacs
If the membrane that forms the placenta (the chorion) has already developed when they split- share a placenta
If not separate
Earlier split after conception means different sacs, few days later is shared
Placenta and similarities
This can affect development: Monozygotic twins who shared a placenta are more similar than those who did not share a placenta on measures such as IQ, on 20 different personality measures, on birth weight, and congenital anomalies
Why and how do monozygotic twins become different?
Intrauterine environment
——– some monozygotic twins have non-identical prenatal environments, perhaps having different
placentas (and thus different avenues of access to maternal resources) and perhaps having their own amniotic
fluid- differences in cognitive and personality development
Developmental Noise
——–stochasticity in the process
of development
- describes developmental differences that cannot be accounted for by differences in genes or by differences in the environment -Have you ever seen a dog (or a person) with two different colored eyes? This is not because different genes contributed differently to the development of each eye - developmental noise
Epigenetics
—–Epigenetic modification can occur during development and throughout the lifespan, and these modifications may not be identical in two twins
Specialized niches -
——-one person really good at something - Siblings, including twins, may have psychological adaptations designed to steer them toward different specializations, or niches, in order to reduce direct competition between them in their
local environment.
Dizygotic twins and heritability
two different zygotes and thus have different genomes - fraternal twins
Mother releases more than one egg into fallopian tubes during ovulation - 2 eggs and each get fertilized
Somewhat heritable but must be in the mother’s family - skips a generation - if one is a male - not relevant - but daughters might - only skips if there is males
Father - may pass this on to his daughters
Teratogens - what effects?
A toxin that if ingested during pregnancy can adversely effect fetal development
Can be illegal drugs, legal drugs, medications, viruses, environmental pollutants
The type and severity of the effects of teratogens depends on the timing of the exposure: they will interfere most with the development of whatever organs or systems are currently developing.
Highest levels of vulnerability occur during the embryonic period, because this is when most organs and many systems develop.
Not vulnerable to drugs prior to implantation because no connection to mothers blood system
Morning sickness adaptive function
designed to protect a fetus from teraogens - adaptation that protects the developing fetus from toxins in the diet when the fetus is most vulnerable
First trimester - aversion to foods with plant toxins
Repulsed by smell of coffee - aversions to animal products which may be contaminated by pathogens and toxins
Women who experience morning sickness are less likely to have a miscarriage - women who vomit are even less likely to miscarry - severe nausea and vomiting in preg - fewer preterm births
Screens some teratogens that might have been toxic during the EEA - modern toxins may be undetectable
Cognitive Adaptations During Pregnancy
Male Faces
Dangers
Healthy
Nesting
Commonly held belief that women who are pregnant lose cognitive function (especially short-term memory) - women who are pregnant have a better memory for male faces than non-pregnant women
pressing adaptive needs - avoiding dangers, protecting their developing fetuses, social threat that unknown males might pose, show increased negativity toward unknown people compared to non-pregnant women - become more socially selective - drive to protect the fetus - unfamiliar people have pathogens
Prefer to look at healthy over unhealthy faces - more true of pregnant women
Nesting instinct - in 3rd trimester - organize their household in preparation for the baby and become more of a home-body
Labor is intiated when…
baby’s brain and adrenal glands produce hormonal signals - the mother’s brain produces oxytocin in response - rhythmic contractions of the uterus - typically starts about 38 weeks after conception
3 stages of labor
DAAB
Dilation
—–Dialation of the cervix 10 cm
—–Rhythmic contractions distend the cervix and push the amniotic sac towards the cervix - will usually burst during this stage
—–Lasts 12 to 24 hrs the first time a woman gives birth and 3 to 8 in later births
—–Contractions are gentle infrequent and irregular
—–Contractions intensify and become more frequent - intense by the end of this stage - contraction becomes continuous
Active delivery
—An hour for first time mothers - baby moves through the birth canal
—Urge to push by contracting abdominal muscles and pushing expels the baby
—Crowning - appearance of the head at the opening of the birth canal
—-Stage over when baby expelled
Afterbirth delivery
—The placenta actually disengages from the uterine wall and is expelled through the birth canal
10 to 20 min
India birth
birthing women are isolated
from the family in order to avoid contamination
Malay women
modest and prefer to be attended by female health-care providers and to be protected by a screen or curtain
Samoan women
prefer to go to their own mothers’ home the first time they deliver
Birth Medicalization
Throughout the world and throughout history, the most common birth experience took place in the mother’s home, with the help of other women such as midwives or doulas.
The North American practice of giving birth in a medical institution such as a hospital and under the direction of a male medical expert is unusual in historical terms.
By comparison, a third of babies born in The Netherlands are born at home, usually attended by a midwife
Consequence of medicalization
BRACI
- Women is more likely to be required to labor and deliver on back - traditional births more likely to involve a squatting position or position based on babys position
- Rules about who may be present
3.Women hospitalized are more likely to be given anesthesia or sedatives during labor - medications passed onto baby
- More likely to have a cesarean delivery
- isolation of the childbearing mother from the rest of the family means that a young
woman has less opportunity to witness birth: Her own first labor and delivery may be her first experience with the process.
Birth Complications - Cephalopelvic disproportion
Babys head is too large to pass through the mother’s pelvis - sizes are mismatched - scalp plates can move
Conflict between gestational period and mother’s pelvis size based on babys maturity
Birth Complications - Irregular position
Feet or ass first - can be delivered but cesearan may be preferred
Birth Complications - Pre-eclampsia
Extremely high blood pressure that results form pregnancy - occurs after 32 weeks - infant increases mothers blood pressure in order to increase nutrients - increase even more if father is not a long term partner
Can threaten kidney and liver function - endanger mother’s health
Medication can bring bp down
Immediate delivery can resolve this and may be recommended in the most severe cases
Birth Complications- Umbilical Prolapse
Umbilical cord exits the birth canal before the fetus - occurs in fewer than 1% of deliveries but can be a serious complication
Fetus will compress cord - restricting its oxygen - can result in brain damage or death
Modern birth environment - death less than 3 %
Calls for immediate delivery - so infant can access oxygen
Prematurity
What week considered?
Low birth weights
Complications?
Born prior to the 37th week of gestation
Low birth weight - less than 5.5 pounds
Very low birth weight - less than 3.3 pounds
Less than 2.2 - extremely low birth rate
difficulty breathing - lungs mature in the final month of pregnancy
—If premature birth anticipated - mother can be injected with steroids that spur the maturation of the lungs
Cerebral palsy - 3 and 9% - have visual impairments at a rate of up to 38% and cognitive impairments at a rate of 27%
minor troubles with motor development, behavioral disorders and learning delays - hide the face that most preterm infants are developing normally by age 3
Why are babies born prematurely
Born early because… multiple births - no more room, poor nutrition, smoking, physical stress - younger than 19 or older than 35
Fetus in distress or not growing -early delivery
NICU Survival Rates
NICU survival rates are high - 90% weighing less than 2llbs survive - 50 % weighing less than 1 pound
SIDS
Risk Factors?
PLSFP
SIDS - death of an apparently healthy baby for no identifiable reason - rare but incidence peaks between 2-4 months
No clear cause - infant reflexes that would startle the child who ceased to breath are disappearing but volitional mechanisms that ensure continuous breathing have not yet matured
Infants born preterm
Babies born with low birth weights
Parents who smoke
Infant sleeps face down
Bed with lots of pillows and plush covers
Neurons -
A nerve cell. A cell specialized for conducting information between the brain and other body parts or within the brain. - 100 billion
Dendrite
One of the fibers extending from the cell body of a neuron, designed to receive a signal from a nearby neuron
Axon
The long fiber that runs the length of a neuron, conducting the electric signal from the cell body to the terminals.
Synapse
The gap between two neurons, across which a chemical signal is transmitted.
the fetus’s brain is the fastest growing organ, by weight,
Neurogenesis
When?
What happens
When does differentiation start?
First 20 weeks after conception
Mostly 3rd to 18th week
Most neurons until you die were created in the first 20 weeks after conception
250 000 new neurons per minute
Differentiation - begins around 20 weeks after conception
Neuronal production is almost
complete by 18 weeks after conception, although some areas of the brain are capable of neuron production in adulthood
Neuron Migration
How do they get to their targets?
When is it complete?
Neurons are produced near the center of the brain, then move toward their destination in a process called neuron migration
Chemical attraction to its destination and target
Different types of cells migrate at different times during development, and cell migration is complete by 7 months of gestation
Differentiation
When and what?
begins at around 20 weeks after conception
cells increase in size and become more elaborate
neuron first grows an axon, which in some cases can be quite long, and then grows a dendrite, which forms an elaborate bush-like structure
This arborization, as it is called, increases the neuron’s capacity to form connections with other cells.
myelination
encases the long axon of neurons in a myelin sheath, which serves as insulation and allows the transmission of an electrical impulse with greater efficiency.
Myelination is known to continue into adolescence.
Synaptogenesis
Synaptic density peak?
The growth of synapses between neurons.
Most neurons have connections with thousands of other neurons, resulting in trillions of connections in the brain.
starts prenatally and proceeds rapidly before and after birth.
Synaptic density peaks at about 1 year of age, and the average number of connections for each neuron is about 16,000 at the peak.
peaks in the visual cortex at around 1 year of age, it does not peak in the prefrontal cortex until a child is just less than 4 years of age.
Synaptic Pruning
When?
What does the process provide?
Synaptic pruning, a process during which synaptic density decreases as synaptic connections are lost, is an important part of the developmental process.
Synapses that are used are preserved, and synapses that are not used disappear.
synaptic pruning peaks at different times in different parts of the brain. In the
visual cortex, synaptic pruning takes place between 1 and 10 years of age. It occurs later in the prefrontal cortex, continuing into young adulthood. At its peak, as many as 100,000 synapses disappear per second
provide a great deal of plasticity. The human brain is surprisingly
good at recovering from injury, provided the injury happens early in life when there is a surplus of synaptic
connections.
Hemispheric Specialization
The left side of the brain is involved in processing sensory information and sending motor commands to the right side of the body, while the right side of the brain processes sensory information and sends motor commands to the left side of the body
left side of the brain processes language information, whereas the right side of the brain is thought to underlie spatial thinking and visual imagery
differences between the size and shape of the two hemispheres that are already evident at birth. Even infants use the left hemisphere to process speech related information
Henry Ziegland Story
Bullet in tree - who killed him
single unique cause of an event is not always identifiable. Cause of an event is something that our minds are designed to perceive not something the world is obliged to supply
Understanding Causality
Relationship between causality and heritability?
Fallacy of exclusive determinism
not usually a single cause- many things you could manipulate to change the outcome
Factors which may make an event possible but which we do not consider to be the cause because we take them for granted - house burns down bc of oxygen
Fallacy of exclusive determinism - tendency to identify a single cause of an event
Cake Analogy
Baked a cake - what caused the cake the recipe or the ingredients - change the genetics, development changes, change environment - development changes
Heritability - What does it NOT tell you?
Snowflake Analogy
Not the relative contribution of genetic info
Not an estimate of malleable
Does not tell you whether something is inherited
Moore - snowflake analogy - what causes a snowflake?
—-2 groups of scientists - one believes humidity causes and the other believes that temperature causes
Both determined a statistical relationship in variance but their study sample mattered - two different environments
—-if you wanted to fully describe the formation of snowflakes - have to know all about the characteristics of a water molecule and the factors affecting freezing - know the circumstances - no one factor is ever the cause of an outcome
Asking if a trait is a result of genes or the environment is like asking if a snowflake is a result of temperature or humidity - need both genetic info and species typical environment
The Heritability Statistic - Galton
LTEV
measure extent to which traits “breed true” meaning the extent to which traits that are seen in parents will develop in offspring and subsequent generations
How much of the variance in the entire population is (statistically) accounted for by the variance in genes.
- Applies to a large pop- never to an individual
- Applies only to a particular group living at a particular time
- Can differ markedly for groups of people who grow up in very different environments
- Can’t be measured if there is no variance - don’t talk about heritability of number of fingers or toes - if theres not meaningful variance -
Galton
first person to use the terms nature and nurture
Eminence - combination btw SES and professional status - people who had reached eminence were likely to be related to each other - nature a greater contributor - not a good conclusion
He made no effort to control for environmental factors - everyone was of high social status
Statistical innovations - created the regression analysis - allowed him to estimate relationship btw various measures
More special case of correlation coefficient statistic - measure of the relationship between any two sets of numbers
Define Heritability
An estimate of the proportion of the measured variance of a trait among individuals in a given population that is attributable to genetic differences among those individuals.
Non-shared environment
Different influences based on gender, financials at birth, age at war or environmental crisis, birth order
Anything that’s different with the kids across the family
First born children - more likely to conform to the parent’s values and expectations
Intelligence
Cognitive capacities such as general knowledge, memory, and problem solving as measured by standardized intelligence tests
Binet and Simon
employed to create a method to measure intelligence as a way to identify school children who needed special education
Binet Simon Intelligence test - successful in predicting school success - correlated with grades at the time of testing and for years to come
Used in military afterward
Current IQ tests
Standford Binet intelligence scale - derived from their original test and preserves some key features
—-Assesses quantitative reasoning, fluid reasoning, visual-spatial processing, general knowledge and working memory
—-Designed for school age children but can be used to measure adult intelligence
Weschler tests - 2yr 6m to 7y 3m- can be assessed using the preschool and primary scale
Focus on skills that are relevant to school performance - 4 categories
1. Verbal comprehension
2 - Perceptual reasoning
3 - Working memory
4 - Processing Speed
WPPSI - preschool
WISC - for children 6-16
WAIS - 16yrs+
Flynn Effect
Why does this happen?
The rise in uncorrected raw scores on intelligence tests seen in each successive generation
Average IQ is 100 - normed so the average stays at 100 - IQ would be increasing if scores were not updated -
Without updating scores have increased 10 points over a 25 yr period
–Could be: better nutrition, more familiar with test-taking, better schooling, higher literacy rates
—Most of the improvement takes place in the lowest range of scores - stressors experienced by the least advantaged are being relieved over the decades
Infant IQ Testing
Bayley Scales of Infant Intelligence
Measure intelligence in infants aged 1m to 42m
Motor Scale - Records how well the infant reaches for and grasps things, and throwing
Mental Scale - how well infant follows directions, searches for things and reaches for a preferred object
Behavior rating scale - emotional responsivity and emotional regulation
Effective in identifying children developing with exceptional intelligence or deficits
Marginally successful at predicting later intelligence
Better at identifying delayed infants
NOt a strong predictor of later IQ or academic success
Single Intelligence
Spearman - Early evidence for g - predicts performance on all measures of intelligence probed by standardized intelligence tests
seven distinct underlying constructs: perceptual speed, word comprehension, word fluency, space competence, number competence, memory, and induction
Multiple Intelligences
Gardner is a more contemporary theorist who has proposed that there are an even greater number of intelligences.
linguistic, logical-mathematical, and spatial, he suggests that there is a musical intelligence and a bodily-kinesthetic intelligence. Also unique to Gardner’s model are interpersonal intelligence, intrapersonal intelligence, naturalistic intelligence (understanding the natural world), and existential intelligence, emotional intelligence
Is intelligence singular or multiple?
No right or wrong all correlated - “factor analysis” can give you any number of underlying factors, depending entirely on how many you want
All are correlated together so it makes sense that there is one and it makes sense that there are multiple
Stability of IQ
IQ is reasonably stable over time, meaning that knowing someone’s IQ at one age allows for a reasonably accurate prediction of IQ at a later age.
The stability of IQ seems to start at around 5 years of age. Infant IQ tests tend to have much lower correlations with later IQ measures. In fact, the correlation between IQ at one year of age and in adult IQ is close to zero
the speed at which a child habituates during the habituation paradigm and their preference for the novel stimulus in the habituation paradigm, is reliably related to adult IQ - taps developing working memory, processing speed, and executive function
IQ Percentage predictions of success
they predict academic success quite well - 58% with achievement in elementary, 24% hs and 19 in grad school
Predicts professional performance
. Higher IQ is associated with higher prestige careers, such as medicine, law and engineering , and correlates with occupational success more broadly as well, more published articles
Home Influences on IQ
emotional and verbal responsivity of the mother,
lack of excessive restriction and punishment, the organization of the environment,
availability of play materials,
mother’s involvement with the child
variety of stimulation
parents who encouraged their children to excel intellectually and who were neither too severe nor too permissive in their discipline had children with higher IQ scores
School Influences and IQ
attendance affects IQ.
small drop in IQ from the beginning to the end of summer vacation, when children are not in school
attending higher-quality schools have higher IQs,even when time spent in school is taken into account
Schools that have clear academic goals and a strategy
Schools supporting student involvement
