Part 6: Labor

Question 1

What enzyme is present in the placenta that ensures fetus cortisol levels are not in excess?

Answer 1

• Type 2 11-beta HSD.
  
  • Converts cortisol to cortisone.

Question 2

Defects in placental type 2 11-beta HSD are associated with what birth defects?

Answer 2

low birth weight.

Question 3

What placental hormone targets the maternal adrenal cortex to secrete cortisol + DHEAS?

Answer 3

placental CRH.

Question 4

Effect of cortisol on placental CRH levels:

Answer 4

• increased placental CRH.
• positive-feedback system.

Question 5

What two hormones lead to surfactant production in the fetal lungs and maturation of the fetal lungs?

Answer 5

Cortisol + placental CRH.

Question 6

What molecule is responsible for the increase in E3 levels at the end of the third trimester?

Answer 6

Fetal and maternal DHEA.

Question 7

What occurs when E3 > E2 levels at the end of the third trimester?

Answer 7

• E3 activates endometrial estrogen receptor.
• Increased contractile protein expression in myometrium.
• Myometrium contraction promoted.

Question 8

What enzyme is expressed by the placenta that converts maternal DHEAS to DHEA?

Answer 8

steroid sulfatase

Question 9

What causes contraction of the myometrium during labor (4)?

Answer 9

1. cortisol.
2. oxytocin.
3. prostaglandins.
4. decreased progesterone levels.

Question 10

Around the time of labor, the corpus luteum begins to secrete which hormone?

Answer 10

relaxin.

Question 11

Relaxin hormone causes (2):

Answer 11

1. cervix relaxation (cervical ripening).
2. pelvic ligament softening.

Question 12

A full-term pregnancy is roughly how many weeks?

Answer 12

39-42 weeks

Question 13

When do CRH levels peak during pregnancy?

Answer 13

birth

Question 14

When does the myometrium stop growing, and what effect does this have?

Answer 14

• late mid-third trimester.
• fetal growth continues; uterine wall stretches.
• stretch-induced contraction promoted.

Question 15

Preterm labor: what three drugs can be given and why?

Answer 15

1. corticosteroids: ensures proper fetal organ development.
2. tocolytic agents: inhibit calcium; halts muscle contractions.
3. 17α-OHP4 (progestin): progesterone prevents muscle contractions.

Question 16

5 common reasons for infertility:

Answer 16

1. Ovulatory dysfunction (obesity; BBT).
2. Uterine disorder (fibroids).
3. Tubal disorder (STD).
4. Peritoneal factor.
5. Male factor.

Question 17

What hormone is upregulated during pregnancy to promote lactation (milk production)?

Answer 17

prolactin.

Question 18

What hormone is an inhibitor of prolactin?

Answer 18

dopamine.

Question 19

What hormones block milk letdown (secretion) from occurring during pregnancy?

Answer 19

estrogen and progesterone.

Question 20

Estrogen and progesterone promote the growth of what two components of breast tissue for milk production?

Answer 20

• Estrogen: breast ductal epithelium.
• Progesterone: breast alveoli.

Question 21

What hormone stimulates the proliferation of mammary ductal epithelial cells during pregnancy?

Answer 21

estrogen.

Question 22

What hormone promotes the growth of mammary alveoli during pregnancy?

Answer 22

progesterone.

Question 23

What reflex develops in mothers after giving birth?

Answer 23

suckling reflex.

Question 24

The suckling reflex is dependent on what two hormones, and for what?

Answer 24

• Prolactin: lactation (milk production).
• Oxytocin: milk letdown.

Question 25

Prolactin is secreted from:

Answer 25

anterior pituitary lactotrophs.

Question 26

Oxytocin is secreted from:

Answer 26

posterior pituitary.

Question 27

How does the suckling reflex decrease gonadotropin (LH/FSH) secretion (2)?

Answer 27

1. blocks preoptic nucleus activity; GnRH not secreted.
2. promotes PRL secretion; PRL suppresses gonadotropin secretion.

Question 28

The lack of menstrual cycling in a nursing mother is due to (2):

Answer 28

1. increased prolactin.
2. suckling reflex.