Anatomy Final Pregnancy

pregnancy

events that occur from fertilization until the infant is born

gestation period

last menstruation period to birth

-typically about 270 days

conceptus

the pregnant woman’s developing offspring (embryo or fetus)

-”the product of conception at any point between fertilization and birth”

embryonic period

fertilization through the 8th week

fetal period

9th week through birth

fertilization

oocyte & sperm

sperm fuses with an egg & forms a zygote

coitus

sexual intercourse

oocyte viability duration

12-24 hours

sperm viability duration

24-72 hours

for fertilization to occur

coitus must occur no more than 3 days before to 24 hours after ovulation

ovulated oocyte is encapsulated by

-corona radiata

-zona pellucida

corona radiata

-made of granulosa cells (secrete estrogen and progesterone)

zona pellucida

-coats the oocyte

-sperm secretes enzyme to penetrate

monospermy

only one sperm is allowed to penetrate the oocyte

mechanisms to ensure monospermy

-fast block to polyspermy

-slow block to polyspermy

fast block to polyspermy

plasma membrane depolarization

-makes oocyte more positive inside which repels more sperm from penetrating

slow block to polyspermy

cortical granules (oocytes) release enzymes destroying sperm receptors

monozygotic

identical twins

dizygotic

fraternal twins

identical twins

-develop from one zygote, which splits to form 2 embryos

-since identical twins develop from one zygote, they will be the same sex

-each twin develops from a separate egg and each egg is fertilized by its own sperm cell

-in very rare cases twins can have the same mother and different fathers

blastocyte implants in

the uterus

teratogen

harmful factors to the embryo

functions of the placenta

-nutrient and gas exchange

-endocrine function

encocrine function of the placenta

including human chorionic gonadotropin (hCG), estrogen and progesterone

placenta is fully formed

by 3 months

formation of placenta

stimulated by implantation

extraembryonic tissues

-chorion

-amnion

-amnionic fluid

-yolk sac

-umbilical cord

chorion

-outermost membrane

-involved with implantation/attachment to endometrium

amnion

fluid-filled sac around embryo/fetus

amnionic fluid

-protection

-temperature regulation

-lung development

-nutrient and waste exchange

yolk sac

-contains very little yolk

-involved with blood cell production early on

-most of yolk sac gets incorporated into GI tract by 20 weeks

umbilical cord

-tube containing blood vessels (go in and out of fetus)

-connects fetus to placenta

human chorionic gonadotropin

hCG

hCG

-levels rise about 2 days after implantation and remain elevated for several months

-”saves” the corpus luteum

prosgesterone prevents

menstruation that would flush away the newly implanted embryo (blocks ovulation & decreases LH synthesis)

progesterone levels

high during pregnancy (except delivery)

progesterone

-prevents uterine shedding (as mentioned above)

-prevents uterine contractions

estrogen levels

stay high until birth happens

estrogen

-uterine/placental growth and development

-fetal development

uterine/placental growth and development with estrogen

promotes the enlargement of uterine muscles and blood vessels, ensuring adequate blood supply to the placenta and fetus

fetal developement with estrogen

estrogen influences the developement of various fetal organs and tissues

effects of pregnancy on the mother

-anatomical changes

-metabolic changes

anatomical changes

breasts enrlage, arola darkn, uterus expands, lordosis is likeley, pelivic ligaments & pubic symphysis relax, weight gain

avergae weight gain from pregnancy

about 30 poulnds

metabolic changes

placenta secretes hormones to stimulate breast maturation, increase maternal metabolism, (increase activation of vitamin D)

why is vitamin D important during pregnancy

helps formore calcium to provide growth of fetal skeleton

physiological changes effects of pregnancy

-GI tract

-urinary tract

-respiratory

-cardiovascular system

GI tract changes

morning sickness (increase estrogen & progesterone), constopation, gastroesophogeal reflux disease (GERD)

morning sickness cuased by

increase of estrogen and progesterone

Urinary tract changes

polyuria (increase urinary production) due to increase blood volume, increased metabolic wastes, bladder compression

respiratory changes

sometimes dyspnea (difficulty breathing: late term) due to enlarged uterus

cardiovascular system changes

increase blood volume (25-40%)

hormonal induction of labor

fetal CRH (hypothalamus) —> fetal cortisl (anteriror)—> increase estorgens (decrease progesterone)—>increase prostaglandins and ocytocin receptors—> increase prostaglandins—> stimulates contractions

pills for abortion

-mifepristone

-misoprostol

mifepristone

blocks progesterone receptors

misoprostol

synthetic prostaglandins

stages of labor

-dilation

-expulsion

-placental

dilation stage

– Time from labor’s onset until the cervix is fully dilated
by the baby’s head (about 10 cm in diameter).
– Typically lasts 6-12 hours

-eventually the ammonion ruptures, releasing ammniotic fluid, an event commonly referred to as the mother’s “water breaking”

early dilation

weak contractions

late dilation

contractions become more vigorous (oxytocin) and rapid

• infant’s head is forced against the cervix with each contraction, the cervix softens, effaces (thins), and dilates

• estrogen likely plays a role with this

expulsion

-vertex position

-breech position

expulsion

-lasts from full dilation to delivery of the infant

-typically lasts 50 minutes in a first birth and 20 minutes in subsequent births

-crowning occurs when the largest dimension of the baby’s head is visible through the vaginal opening

first birth expulsion is typically

50 min

crowning

occurs when the largest dimension of the baby’s head is visible through the vaginal opening

vertex position

head-first

-skull dilates cervix

breech position

buttock-first

-delivery more difficult; often forceps required, or C-section (delivery through abdominal and uterine wall incision)

placental stage

-delivery of placenta (aftebirth)

-usually accomplished within 30 minutes after birth of the infant

infant’s physical status is assessed within

1-5 minutes after birth

infant’s physical status is assessed based on

5 signs (0-2): heart rate, respiration, color, muscle tone, reflexes

-apgar score

apgar score

total score of above healthy scores (8-10 healthy)

umbilical arteries

carry deoxygenated blood from fetus to placenta

umbilical vein

carries oxygenated blood from placenta to fetus

ductus venous

carries blood from umbilical vein to inferior vencava

ductus arteriosus

carries blood from the pulmonary trunk to the aorta

-allows blood to bypass the lungs

foramen ovale

flap covered hole between right and left atria

lactation

-rising hormone levels toward end of pregnancy prepare mammary glands

-colostrum —> then true milk

colustrum

1st 2-3 days (vitamin A, protein, minerals, & igA antiboies

• no fat;little lactose

later turns to true milk

advantages of breast milk

-beneficial chemicals

-natural lacatives help cleanse bowels of meconium/feces

beneficial chemicals in breast milk

IgA (& other uimmunoglobins), other molecules involved with immunity (like complement)

meconium is composed of

materials ingested during the time the infant spends in the uterus (intestinal epithelial cells, lanugo, mucus, amniotic fluid, bile and water)

• sticky, think, dark green