Pregnancy and Fetal Development

Question 1

list the 4 functions of the placenta

Answer 1

1. exchange
2. endocrine
3. chemical protection
4. physical protection

Question 2

describe the exchange function of the placenta (3)

Answer 2

1. gas exchange: O2/CO2
2. nutrients from mom to fetus
3. waste products from fetus to mom for disposal

Question 3

describe the endocrine function of the placenta (6)

Answer 3

1. transient: based on gestation stage
2. estrogen
3. progesterone
4. hCG in primates
5. eCG in mares
6. placental lactogen

Question 4

describe the chemical protection function of the placenta (3)

Answer 4

1. IMMUNOSUPPRESSION: mom immune system not anywhere near baby, this function is not localized to placenta so mom easily sick
2. prevents infiltration by maternal defenses
3. filters toxins: if mom exposed, baby protected

Question 5

what do most embryos look like at 20-30d of gestation?

Answer 5

all look very similar

Question 6

when are embryos referred to as fetuses?

Answer 6

when they become identifiable as their species

Question 7

when do critical organ systems develop, relatively? give an example

Answer 7

early, like the heart

Question 8

describe the growth in length of a fetus

Answer 8

linear

Question 9

describe the growth in weight of a fetus and why

Answer 9

exponential, don’t want baby too heavy too soon= ouch for mom

Question 10

give 3 estimate of fetal age

Answer 10

1. crown to rump length
2. length of femur, radius, or tibia
3. circumference of head

Question 11

what 3 main factors influence fetal growth?

Answer 11

1. genetics
2. environment
3. fetal hormones

Question 12

give the 4 aspects of genetics influencing fetal growth

Answer 12

1. species
2. breed
3. litter size
4. genotype: certain lines of animals may grow faster

Question 13

give the 2 aspects of environment influencing fetal growth

Answer 13

1. maternal: nutrition, size, parity

2. placenta: blood flow, size

Question 14

describe how materal nutrition affects fetal growth

Answer 14

too much or too little of mom’s nutrition can cause growth restriction

Question 15

describe maternal size affecting fetal growth

Answer 15

species dependent, not important for horses, but very important in cattle because of dystocia

Question 16

describe maternal parity affecting fetal growth

Answer 16

number of previous offspring, first time mom makes smaller babies usually

Question 17

give the 3 aspects of fetal hormones influencing fetal growth

Answer 17

1. thyroid
2. insulin
3. growth hormone

Question 18

describe thyroid hormone affecting fetal growth (2)

Answer 18

1. skeletal and muscular development

2. metabolism

Question 19

describe how insulin hormone affects fetal growth (2)

Answer 19

1. increased energy substrate availability

2. stimulates placental growth

Question 20

describe how growth hormone affects fetal growth

Answer 20

stimulates fetal growth

Question 21

in what 3 ways does uterine size change during pregnancy and where do these changes take place?

Answer 21

1. hyperplasia in endometrium: increase in number of cells
2. hypertrophy in endometrium: increase in size of cells
3. stretching in myometrium

Question 22

how much does the myometrium stretch during pregnancy?

Answer 22

stretches so much it’s almost transparent, can see fetus on inside

Question 23

why are there so mnay shunts in fetal circulation?

Answer 23

because the placenta accomplishes so much of the circulation between the umbilical arteries

Question 24

list the 3 shunts that exist in fetal circulation

Answer 24

1. ductus venosus
2. foramen ovale
3. ductus arteriosis

Question 25

what does the ductus venosus bypass?

Answer 25

the liver

Question 26

what does the foramen ovale do with fetal circulation?

Answer 26

shunts blood from right atrium to left atrium

Question 27

what does the ductus arteriosis do for fetal circulation?

Answer 27

shunts blood directly to the aorta

Question 28

what do the foramen ovale and ductus arteriosis do? why?

Answer 28

bypass the lungs, because the placenta already takes care of gas exchange

Question 29

what happens to the ductus arteriosis as it closes up?

Answer 29

becomes a ligament in the heart

Question 30

describe relative levels of P4 in ewes later in pregnancy

Answer 30

higher and increasing

Question 31

describe relative levels of P4 in cows during pregnancy

Answer 31

higher in first trimester

Question 32

describe relative levels of E2 in both ewes and cows during pregnancy

Answer 32

increases towards the end

Question 33

describe relative levels of P4 in mares during pregnancy

Answer 33

P4 high at first, then drops, then increases again from endometrial cups, and then decreases towards the end

Question 34

describe E2 levels in a mare during pregnancy

Answer 34

mares need higher levels of E2 in the second half of pregnancy

Question 35

in terms of placental lactogen profile, which animals somatropic (GH) activity equal to lactogenic (prolactin) activity?

Answer 35

cows and goats

Question 36

in terms of placental lactogen profile, which animals have lactogenic activity higher than somatotropic activity?

Answer 36

ewes, rats, WOMEN

Question 37

what does progesterone do?

Answer 37

maintains pregnancy

Question 38

what are the 2 sources of progesterone?

Answer 38

1. corpus luteum | 2. placenta

Question 39

name the 7 species in which the placenta does NOT take over progesterone production

Answer 39

1. bitch 2. queen 3. alpaca 4. llama 5. camel 6. rabbit 7. goat