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Chapter 2-3

PSYC 251 Chapter Notes - Chapter 2-3: Saccharin, Pitch Contour, Sedative

Course Code
PSYC 251
Elizabeth Kelley

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Chapter 2:
---While in womb, fetuses can detect a range of stimuli coming from the outside world, they can learn from these
experiences and be affected by them after birth.
Prenatal development:
-4th B.C.E: Aristotle  does prenatal life start with the individual preformed, composed of a full set of tiny parts,
or do the parts of the body develop in succession?. He believed in epigenesist: emergence of new structures
and functions during development. *now: epigenetics.
Box 2.1: Beng Beginnings. West Africa tribe: newborn =reincarnation of ancestor (life begins well before birth).
Ancestor’s spirit wru goes back and forth to the spirit village wrugbe until umbilical stump dropped off,
then bb is considered a person (life begins after birth). Encourage the spirit to stay by decorating bb’s face and
body to elicit + attention from others, consult diviners, herbal med to hasten dry-out of umbilical cord.
-Gametes/germ cells (sperm and egg) contain ½ genetic material found in other cells. *Meiosis.
Women gets all eggs during her own prenatal deve; men produce new sperm continuously.
-Process of reproduction:
. An egg launched from woman’s ovaries into fallopian tube.
2. Egg move through the tube toward uterus, emitting chemical substance that act as beacon (come-hither)
signal that attracts sperm to it.
3. Sex near the time the egg is released Conception: sperm+ egg union.
4. Sperm moves 6 hours, 15-17cm from vagina up through uterus to egg-bearing fallopian tube. Only 200
makes it. (fail by: tangled up with other sperm; get in tube with no egg; genetic defects.) **Survival of fittest.
5. Sperm’s head penetrates outer membrane of egg: chem rxn seals the membrane, prevent other entering.
6. Sperm tail falls, gushes content into egg, nuclei of the two merge within hours fertilized Zygote full dna.
Now it’s the three periods of prenatal development:
Germinal: conception and last till zygote becomes implanted in uterine wall.
Rapid cell division.
3-8 wks
Embryonic: after implantation, major deve occurs in all organs and systems of the body. Deve takes place
through the processes of cell division, cell migration, cell differentiation, cell death
as well as hormonal influences
9 wks- birth
Fetal: Cont. deve physical structures, rapid growth body. Increase levels of beh, sensory exp; learning.
Box 2.2: Individual differencesThe first and lastsex differences.
-Y chrom = lighter, swim faster so boys won the race: 120-150 boy/100 girls conceived.
-Girls won survival: 105-boy/100 girl born. Less miscarried, less complications, C-section, deve disorders
(language, learning, dyslexia, attention deficit, intellectual disorders, autism. *This greater fragility of males
continues throughout life. *So far all nature.
-Nurture as in societies, many prefers male leading to death of girls. Sociocultural models of development…
Developmental Processes (4 processes from zygote to embryo then fetus).
1. Cell division/ Mitosis: within 12 hours after fertilization, zygotes divides into 2 equal parts each with full
DNA. It then keep on dividing through the course of 38 weeks newborn with trillions of cells.
2. Embryonic period cell migration: movement of newly formed cells away from their point of origin. Ex.
Neurons that originate deep inside embryonic brain and then travel to outer reaches of the deve. Brain.
3. Cell differentiation: Embryonic stem cells (equal and interchangeable, no fixed fate or function) after a few
division become specialized in structure and functions350 different types with spec. functions. Currently
styding ESC to use in regenerative medicine. What determines this specialization is the genes that gets turned
on/expressed and the cell’s location future deve. )nfluenced by what is going on in neighboring cells.
-- Expt with frog embryos: graft eye region of embryo into belly.
-----if done early in fetal deve: transplanted region still deve normal belly
------if done late: grow an eye in the belly.
4. Apoptosis/programmed cell death: Ex. Cells programmed to die from the hand plates or you get webbed.
Also important is the influence of hormones on prenatal development. sexual differentiation.
All human fetuses can develop either male or female genitalia, this is all based on presence or no of androgen
(class of hormones that includes: testosterone). If present get male sex organ, vice versa. Source of this
androgen is the male fetus itself: 8wks old, testes begin to produce these androgen **Active child.
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Box 2.3: Phylogenetic continuity.
-Common evolutionary history, humans share many characteristics + developmental processes with other living
things. Ex we used mice to found fetal alcohol consumption lead to spectrum disorders. Found also in rat that
fetal learning. *Amniotic fluid, nipple, milk sucking, odor.
Early development:
-Zygote (double in cell# 2x/day) move through fallopian tube to womb…-- day 4: cells arrange into hollow
sphere with a bulge of cells: inner cell mass, on one side. *identical twice form if this inner cell mass split in half
(same genetic makeup).
-1st week: implantation zygote embed in uterine lining + dependent on mom for sustenance. Before end of 2nd
week it will be completely embedded in uterine wall.
-Differentiation on the embedded ball of cells. Inner cell mass embryo, rest of the cells support system:
amniotic sacz + placenta.
-Inner cell mass start as1 layer, in 2nd week folds into 3 each with different deve. Destiny.
Top: Nervous system, nails, teeth, inner ear, lens of eye, outer surface of skin.
Mid: Muscles, bones, circulatory system.
Bottom: digestive, lung, urinary tract, glands.
-Few days after the above differentiation, U-shaped groove forms down center of top layer. Folds at top of groove
joins and fuse neural tube. At the end of neural tube it will swell and brain. Rest = spinal cord.
-Support system:
--Amniotic sac: membrane filled with clear watery fluid where fetus floats. Operates as a protective buffer for
deve. Fetus, provide even temp, cushion. Keeps fetus afloat so it can exercise its weak muscles w/ no gravity.
--Placenta: blood system of mom and fetus come close, prevents it from mixing. However the membrane is
semi-permeable, some elements can pass. Permits exchange of materials carried in bloodstreams of fetus and
mom (O2, nutrients, minerals, antibodies from mom; waste, CO2, urea from fetus). Rich network of blood
vessels including minute ones extending into the tissue of mom’s uterus, total SA = 8square m. B.vessels go from
placenta to embryo and back again are contained in umbilical cord.
-Also act like defensive barrier against host of dangerous toxins and infectious agents in mom’s body. But since
it’s semi-perm, not perfect.
-3rd function: production of hormones: estrogen (increase flow of mom blood to uterus); progesterone
(suppresses uterine contraction that could lead to premature birth).
An illustrated summary of Prenatal Development
-Earlier deve more rapidly than later ones. cephalocaudal development. (head before body, hands before feet).
-4 weeks: embryo curved tightly, head + tail almost touches. Facial features=4 folds- streth and move, fuse and
separate -> face. Round on top =eye, near back of neck =primordial inner ear. Primitive heart visible, beating
and circulating blood. Arm and leg bud.
-5.5 wk: nose, mouth, palates start to differentiate into separate structures.
-8.5 wk: nose mouth almost fully formed. Cleft palate (one of most common defect).
-9 wk: head large +bulging forehead (rapid brain growth). Rudimentary eyes and ears form. Internal organs
present (most need more deve). Sexual differentiation started. Ribs visible, fingers toes emerged, nails
growing. Spontaneous movement small, mom can’t feel.
-11 week: heart achieved basic adult structure. Spine and ribs, major division of brain.
-16 week: growth of lower body accelerates. Movement increased: chest breath movement, reflexes (grasping,
swallow, suck). Intense kick. Genitalia deve, can tell sex.
-18 week: suck thumb like newborn. Fine hair and greasy coating protecting skin from immersion in liquid.
-20th week: head down position. Facial expression: raise eyebrow, wrinkle forehead, move mouth. Gain weight,
amniotic sac = more cramped, leading to decrease fetus movement.
-29th week: brain and lungs sufficiently developed. Can survive if born. Eye can open, move most in REM.
Auditory system functioning and hear, react to diff sounds. Neural activity like newborn.
Fetal behavior: active child. Normal formation of organs and muscles depends on fetal activity; fetus rehearse
behavioral repertoire it will need at birth.
Movement: spontaneously from 5-6wks, bend head and spine. 7 wk= Hiccups (burp reflex prepare for nursing:
remove air from stomach +make room for milk). Move limbs, wiggles finger, grasp umbilical cord, head eyes,
yawn. Backward somersault changes of position. *Prenatal continuity extends into post-natal period: regular
sleep and wake; movement (active fetus= active bb) Swallowing: fetus drink amniotic fluid, pass GI system out.
tongue movement promote deve of palate. Passage of fluid through digestive system helps it mature.
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*Fetal breathing: chest wall in and out. No air taken in/ instead a small amount of amniotic fluid. lung and rest
of resp system (muscles that move diaphragm) need to mature and function: 10weeks- promote its resp
readiness by exercising its lung. Irregular and infrequent first then stabilize.
Behavioural cycles: 5-6 week, constant motion for the next months. Then periods of inactivity gradually start.
*Rest-activity cycles: burst of high activity with no/little at 10 weeks and stabilize. Daily (circadian) rhythms
show (less activity in early morning, more in late evening). Near end, fetus spend >3/4 in quiet and active sleep
like newborn (REM).
Fetal experience: fetus experiences abundance of sensory stimulation.
Sight and Touch: min visual + tactile stimulation from fetus’ own activity. When moving, its hand come into
contact with other parts of its body: grasp umbilical cord, rub face suck thumbs. *Most contact between their
hand and mouth. Bump against walls of uterus. Later respond to maternal movement (rocking, swaying) so their
vestibular systemssensory apparatus in inner ear (movement and balance) are also functioning before birth.
Taste: amniotic fluid contains many flavours. Fetus detects and prefers some *sweet tooth. Injected saccharin to
use fetus to remove excess amniotic fluid in mom. *Taste sensitivity and flavor preferences exist before birth.
Smell: Amniotic fluid takes odours from mom’s diet- Curry, coffee. Comes in contact with fetus’s odour
receptors through fetal breathing, providing olfactory experience. Rat preferring nipple with amniotic fluid.
Hearing: External sounds audible to fetus—voice of ppl to mom. Maternal sounds mom’s heartbeat, b.pump,
breathing, swallow, rude noise from G). Mom’s voice- pitch, rhythm patterns. Fetus change HR showing they
can distinguish music and speech near mom’s belly. (eart rate decelerate when mom talks = shows interest.
Fetal learning:
-Habituation: provided direct evidence for human fetal learning. Decrease in response to repeated or continued
stimulation. (HR slow = interest. Repeated exposure HR change decrease and then stop =bored). When new
stimuli present HR slow again. Shown at 30 weeks CNS sufficiently developed for learning + ST memory.
- Bb prefer pads saturated with own amniotic fluid (keep head oriented longer toward that scent). Extend to spe.
Flavor ingested by mom: ate anise while pregnant = bb like anise). *Long-lasting taste preference… carrot juice.
*Persistent effect of prenatal food preference. chili peppers, ginger, cumin…
-Rmb sounds they heard in womb: prefer + recognize familiar story heard during pregnancy (sucking pattern).
-Additional auditory preferences: based on prenatal experience. prefer mom’s voice, esp the version that has
been filtered to sound the way it did in womb. Prefer language they heard in womb (French by mom/ Russian).
-Fetal brain likely not deve enough to process language meanings and liquid environment filters out detailed
speech sound leaving only pitch contour and rhythmic patterns…
Hazards to prenatal development
-Most common= spontaneous abortion: miscarriage. / fetus don’t get born, / miscarriage occurred before
detected pregnancy, 15% recognized pregnancy miscarriage.
-25-50% women experience at least 1; 1% couple recurrent miscarriage. *Genetic factor most common.
Environmental influences: Minamata disease --- large amounts of mercury. *Methylmercury poisoning. Child
born with cerebral palsy, intellectual disabilities, host of other neuro disorders.
*Teratogens: environ. Agents with potential to harm fetus. Result in damage from mild to fetal death. Factor
affecting severity of effect of potential teratogen is TIMING. *Sensitive period- major organs more vulnerable
as their basic structures are being formed. Ex. Thalidomide- morning sicknesslimb deformities.
-Another factor is AMOUNT + LENGTH OF EXPOSURE—dose-response relation: greater exposure more
harm. But risk factors often occur in combinationmultiple risk factors can have cumulative impact.
-Fetal programming: belated emergence of effect of prenatal experience fetus metabolism adjusts to level of
nutritional deficiency in womb. If after birth eat a lot, metabolism still lowobesity.
-Sleeper effect: impact of agent not apparent for many years. Ex. Hormone DES adult and adolescence later
have elevated rates of cervical and testicular cancers.
-Legal drugs: 2009 H1N1 swine flue vaccine and Tylenol (acetaminophen) physician unsure appropriateness.
Acne medication Accutane (isotretinoin) are human teratogens that can cause severe birth defects/ fetal death.
Thus women need to use contraceptive and pregnancy test before they can be prescribed. However 2 most
havoc legal drugs: nicotine (cigarettes) and alcohol *lifestyle choice rather than med remedy for a condition.
1. Cigarette smoking 8% mom: Smokingless O2 in momless also in fetus. Fetus makes less breathing
movements while mom smoke. Fetus also metabolize some cancer-causing agents in tobacco. Mom also inhale
gases from other smoker second hand smoke indirectly affected fetal oxygen. These mom less sensitive and
warm w/ bb.
*CON: slowed fetal growth, low birth weight. Smoking also may be linked to increased risk of SIDS.
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