Pregnancy and Fetal Development Flashcards
list the 4 functions of the placenta
- exchange
- endocrine
- chemical protection
- physical protection
describe the exchange function of the placenta (3)
- gas exchange: O2/CO2
- nutrients from mom to fetus
- waste products from fetus to mom for disposal
describe the endocrine function of the placenta (6)
- transient: based on gestation stage
- estrogen
- progesterone
- hCG in primates
- eCG in mares
- placental lactogen
describe the chemical protection function of the placenta (3)
- IMMUNOSUPPRESSION: mom immune system not anywhere near baby, this function is not localized to placenta so mom easily sick
- prevents infiltration by maternal defenses
- filters toxins: if mom exposed, baby protected
what do most embryos look like at 20-30d of gestation?
all look very similar
when are embryos referred to as fetuses?
when they become identifiable as their species
when do critical organ systems develop, relatively? give an example
early, like the heart
describe the growth in length of a fetus
linear
describe the growth in weight of a fetus and why
exponential, don’t want baby too heavy too soon= ouch for mom
give 3 estimate of fetal age
- crown to rump length
- length of femur, radius, or tibia
- circumference of head
what 3 main factors influence fetal growth?
- genetics
- environment
- fetal hormones
give the 4 aspects of genetics influencing fetal growth
- species
- breed
- litter size
- genotype: certain lines of animals may grow faster
give the 2 aspects of environment influencing fetal growth
- maternal: nutrition, size, parity
2. placenta: blood flow, size
describe how materal nutrition affects fetal growth
too much or too little of mom’s nutrition can cause growth restriction
describe maternal size affecting fetal growth
species dependent, not important for horses, but very important in cattle because of dystocia
describe maternal parity affecting fetal growth
number of previous offspring, first time mom makes smaller babies usually
give the 3 aspects of fetal hormones influencing fetal growth
- thyroid
- insulin
- growth hormone
describe thyroid hormone affecting fetal growth (2)
- skeletal and muscular development
2. metabolism
describe how insulin hormone affects fetal growth (2)
- increased energy substrate availability
2. stimulates placental growth
describe how growth hormone affects fetal growth
stimulates fetal growth
in what 3 ways does uterine size change during pregnancy and where do these changes take place?
- hyperplasia in endometrium: increase in number of cells
- hypertrophy in endometrium: increase in size of cells
- stretching in myometrium
how much does the myometrium stretch during pregnancy?
stretches so much it’s almost transparent, can see fetus on inside
why are there so mnay shunts in fetal circulation?
because the placenta accomplishes so much of the circulation between the umbilical arteries
list the 3 shunts that exist in fetal circulation
- ductus venosus
- foramen ovale
- ductus arteriosis
what does the ductus venosus bypass?
the liver
what does the foramen ovale do with fetal circulation?
shunts blood from right atrium to left atrium
what does the ductus arteriosis do for fetal circulation?
shunts blood directly to the aorta
what do the foramen ovale and ductus arteriosis do? why?
bypass the lungs, because the placenta already takes care of gas exchange
what happens to the ductus arteriosis as it closes up?
becomes a ligament in the heart
describe relative levels of P4 in ewes later in pregnancy
higher and increasing
describe relative levels of P4 in cows during pregnancy
higher in first trimester
describe relative levels of E2 in both ewes and cows during pregnancy
increases towards the end
describe relative levels of P4 in mares during pregnancy
P4 high at first, then drops, then increases again from endometrial cups, and then decreases towards the end
describe E2 levels in a mare during pregnancy
mares need higher levels of E2 in the second half of pregnancy
in terms of placental lactogen profile, which animals somatropic (GH) activity equal to lactogenic (prolactin) activity?
cows and goats
in terms of placental lactogen profile, which animals have lactogenic activity higher than somatotropic activity?
ewes, rats, WOMEN
what does progesterone do?
maintains pregnancy
what are the 2 sources of progesterone?
- corpus luteum
2. placenta
name the 7 species in which the placenta does NOT take over progesterone production
- bitch
- queen
- alpaca
- llama
- camel
- rabbit
- goat
