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PSIO469 - Repro > Pregnancy > Flashcards

Pregnancy Flashcards

1
Q

How many sperm arrive at the distal end of the fallopian tube?

A

Less than 50

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2
Q

How long is an oocyte viable for once ovulated?

A

About 24 hours

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3
Q

How long are ejaculated sperm viable for?

A

2-3 days (up to 5)

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4
Q

Sperm capacitation

A

Final maturation of sperm that occurs in the female reproductive tract

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5
Q

39 hours after fertilization what stage does a embryo enter?

A

Two-cell stage

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6
Q

42 hours after fertilization what stage does a embryo enter?

A

Four-cell stage

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7
Q

49 hours after fertilization what stage does a embryo enter?

A

Eight-cell stage

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8
Q

3-4 days after fertilization what stage does a embryo enter?

A

Morula

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9
Q

5-6 days after fertilization what stage does a embryo enter?

A

Blastocyst

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10
Q

Stages of uterine preparation for implantation of an embryo

A
  1. Ciliary movement stimulated by estrogen draws oocyte into the tube.
  2. Progesterone secreted by corpus luteum primes endometrium while embryo develops in oviduct
  3. Endometrial secretions (glycogen) nourish arriving blastocyst
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11
Q

What cells comprise the embryo-derived portion of the placenta?

A

Trophoblasts / trophectoderm

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12
Q

Blastocyst hatching

A

Blastocyst breaking out of the thinning zona pellucida

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13
Q

When does implantation of an embryo occur?

A

About 6 days after ovulation

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14
Q

Decidua

A

Highly-vascularized, maternally-derived endometrium

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15
Q

Some trophoblasts of the embryo penetrate the decidua (endometrium) to form…

A

Syncytiotrophoblast

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16
Q

When trophoblasts contact the decidua (endometrium) they begin to release…

A

proteolytic enzymes

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17
Q

The endoderm gives rise to which tissues?

A

Lining of the respiratory tube and digestive tube

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18
Q

The mesoderm gives rise to which tissues?

A

Skeleton, muscles, circulatory system, and kidneys

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19
Q

The ectoderm gives rise to which tissues?

A

Nervous system, outer layer of skin, hair, nails, and tooth enamel

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20
Q

The yolk sac functions as…

A

Early extra-embryonic circulatory system before internal circulatory system forms

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21
Q

The embryonic disc, amnion, connecting stalk, and yolk sac are derived from…

A

Inner cell mass

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22
Q

Embryonic disc gives rise to…

A

embryo proper

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23
Q

The chorion is derived from…

A

Trophoblasts

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24
Q

Chorion

A

Outermost fetal membrane around the embryo and amnion

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25
The connecting stalk becomes...
The umbilical cord connecting the embryo to the chorion
26
What does the chorion eventually fuse with?
Amnion
27
Amnion
Inner membrane surrounding embryo
28
When is an embryo called a fetus?
> 8 weeks post-fertilization
29
Common name for dizygotic twins
Fraternal
30
Common name for monozygotic twins
Identical
31
Placental functions
1. Respiratory organ 2. Excretory organ 3. Nutrient delivery 4. Endocrine organ
32
Protein hormones of the placenta
- Human chorionic gonadotropin (hCG) - Corticotropin releasing hormone (CRH)
33
Steroid hormones of the placenta
- Progesterone - Estrogen
34
Site of production of hCG
Syncytiotrophoblast
35
What hormone is hCG structurally similar to?
LH (glycoprotein family)
36
When is hCG detectable?
6 days after implantation
37
When does hCG peak?
9-12 weeks
38
Functions of hCG
- Signals implantation of the embryo - Prevents luteolysis (maintaining corpus luteum) - Stimulates luteal production of progesterone
39
hCG can be used to clinically mimic...
an LH surge in infertile women triggering ovulation
40
When does hormone production shift from the corpus luteum to the placenta?
10-12 weeks
41
Role of progesterone in early pregnancy
1. Inhibits uterine contraction 2. Promotes formation of mucus plug
42
Role of estrogen in early pregnancy
1. Stimulates myometrial growth 2. Stimulates gap junction and oxytocin receptors in the myometrium
43
Parturition
Process of labor and delivery
44
Pitocin
Synthetic oxytocin
44
If it only takes one sperm to fertilize an egg, explain why less than 20 million/mL can lead to infertility
Small probability they will reach the distal end of the fallopian tube. If less sperm are ejaculated, the chances are even smaller.
45
Describe the stage of oogenesis at which the oocyte is ovulated
Meiosis II at metaphase; 23 chromosomes and 2 sister chromatids
46
Describe the sequence of events involved in gamete transport, capacitation and fertilization
- Sperm penetrates to cumulus cells - Binds to zona pellucida - Rise in ca in sperm causes an acrosomal reaction - Acrosomal hydrolytic enzymes dissolve zona pellucida for fusion of oocyte and sperm. - Sperm DNA and nucleus enter egg - Rise in Ca within the oocyte causes a cortical reaction and the zona pellucida to harden and prevent additional sperm from binding
47
ZP3
ZP protein that binds to sperm and stimulates acrosome reaction
48
Describe the events that take place during the first week after ovulation and fertilization
- Ciliary movement stimulated by estrogen moves embryo towards uterus as progesterone prepares endometrium for fertilization. - Within 5-6 days the zygote develops into a blastocyst.
49
Describe the structure of the blastocyst and the need for hatching
Trophoblasts surrounding an inner mast cell hatch out of the hardened zona pellucida
50
Describe the sequence of events that occurs during implantation
- Embryo hatches out of degenerating ZP - Trophoblasts contact endometrium and release proteolytic enzymes - Some trophoblasts fuse/penetrate the endometrium to form synctiotrophoblasts - Layer of endometrium surrounds the embryo by day 12
51
The placenta is derived from...
both embryonic (trophoblast) and maternal (decidua) syncytiotrophoblast tissues
52
Differences between fraternal (dizygotic) and identical (monozygotic) twins
- Fraternal: two zygotes - Identical: split of early embryo
53
DC/DA twins
Two zygotes implant separately 2 chorion 2 amnions
54
MC/DA twins
Twins implant close together and have fused placenta or single placenta "1 chorion"
55
MC/MA twins
1 chorion and 1 amnion
56
Explain why MC/MA (and especially conjoined) twins have the lowest survival rates
Umbilical cords get tangled cutting of nutrients to fetus. Combined twins end up sharing organs as well.
57
Describe basic fetal and maternal blood flow to the placenta
1. Maternal arteriole 2. Pool of maternal blood in placenta 3. Chorionic villus 4. Chorionic tissue 5. Fetal vessels 6. Umbilical cord artery 7. Fetus 8. Umbilical vein 9. Maternal venule
58
Components that CAN cross the placenta (anything with a MW less than 500)
- Oxygen - Carbon dioxide - Glucose - Amino acids - Thyroid hormone - Alcohol - Cocaine
59
Can protein hormones and insulin cross the placenta
No, their molecular weight is too big.
60
Where is CRH produced?
Placenta
61
Which hormone is CRH similar to?
Hypothalamic CRH
62
Function of CRH
- Placental clock - Leads to parturition
63
Explain how the production of progesterone, estrone, estradiol, and estriol during pregnancy requires cooperation between the mother, placenta, and two fetal organs
- Fetus converts progesterone to androgens - Placenta converts androgens to estrogens - Cholesterol comes from the maternal blood 1. Fetal adrenal cortex = cholesterol + progesterone --> DHEA 2. Fetal Liver = DHEA --> 16-OH DHEA-S 3. Placenta = 16-OH DHEA-S --> estriol - estriol and progesterone enters the maternal blood
64
Describe uterine involution and identify the hormones involved
Uterine involution is the process of the uterus shrinking back to its normal size (takes 4-6 weeks for endometrial tissue to disintegrate). Hormones involved: stimulated by rapid decrease in estrogen and progesterone and oxytocin release in lactating mothers.

PSIO469 - Repro (18 decks)

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