Endo - Pregnancy, Labor, & Lactation

Question 1

What are synchiotrophoblasic cells? What do they produce?

Answer 1

Cells of the growing placenta.

Produce hcG.

Question 2

Where does hcG bind?

Answer 2

Binds to LH receptors on corpus luteum.

Question 3

When hcG binds, what hormone is produced?

Answer 3

Progesterone.

Question 4

What does progesterone do in pregnancy?

Answer 4

Maintains quiescent, non-contractile environment.

Question 5

What 2 hormones are high in first half of pregnancy?

Answer 5

hcG and Progesterone.

Question 6

What hormone is high towards the end of pregnancy?

Answer 6

Estrogen.

Question 7

What does a high estrogen:progesterone ratio do at the end of pregnancy?

Answer 7

Causes myometrium in uterus to be more irritated and active – could aid in starting contractions.

Question 8

What hormone from the mother aids in contractions?

Answer 8

Oxytocin from the posterior pituitary.

Question 9

What hormone from the fetal adrenals aids in contractions?

Answer 9

Prostaglandins (PF2-a) and more Estrogen.

Placenta secretes CRH.
CRH binds to fetal pituitary to release ACTH.
ACTH binds fetal adrenal glands to release DHEA (precursor androgen).
DHEA gets converted to Estrogen by aromatase.
Estrogen causes increase in PF2-a which causes contractions.

Question 10

What else can cause a mother to have earlier-than-expected contractions?

Answer 10

Stress / catecholamines.

Question 11

What is the Ferguson reflex?

Answer 11

When the fetus moves through the cervix, it causes stretching and more release of oxytocin.

Question 12

What is the alveolus?

Answer 12

The functional unit of breast that excretes milk.

Question 13

What does prolactin do?

Answer 13

Milk synthesis.

Binds to alveoli in breasts for milk production.

Question 14

What hormone helps excrete breast milk?

Answer 14

Oxytocin.

Smooth muscle cells of breasts have oxytocin receptors causing squeezing of alveoli and excretion of milk.

Question 15

What is estrogen’s role in breast development?

Answer 15

Increases fat deposit (puberty & pregnancy), prolactropes growth.

Question 16

What is progesterone’s role in breast development?

Answer 16

Alveoli growth.

Question 17

What hormone regulates prolactin?

Answer 17

Dopamine. Tonic negative regulation of prolactropes from secreting prolactin.

Question 18

Where is Dopamine produced?

Answer 18

Arcuate Nucleus in the Hypothalamus.

Question 19

What stimulates breast milk production?

Answer 19

Suckling of breast by infant.

Breast –> spinal afferent –> hypothalamus –> temporary decrease in dopamine –> increase prolactin –> breast milk synthesis.

Question 20

What hormone regulates the short loop negative feedback for breast milk?

Answer 20

Prolactin.

High amounts of prolactin reach the Arcuate Nucleus in the Hypothalamus to trigger dopamine neurons to release dopamine. Breast milk cannot do long loop negative feedback.

Question 21

How does frequent breast feeding act as a birth control?

Answer 21

GnRH decreases with frequent breast feeding. Prevents ovulation.

Dopamine neuron has synaptic contact with GnRH neuron and causes decreased secretion when dopamine is activated.

Question 22

What is Sheehan’s syndrome?

Answer 22

Panhypopituitarism from massive blood loss in delivery of baby.

Can occur in males too.