Pregnancy and Lactation

Question 1

Capacitation

Answer 1

Occurs prior to fertilization while the sperm is in the female tract

*Sperm can last two days here

Question 2

Acrosomal Reaction

Answer 2

Sperm binds w/ ZP3 receptor inducing a rise in intracellular Ca2+

=>Release of acrosomal cap contents that digest the zona pellucida and cause an increase in the oocyte Ca2+ leading to

1. Completion of meiosis
2. The cortical reaction

Question 3

Cortical Reaction

Answer 3

Electron dense granules fuse w/ the plasma membrane of the oocyte preventing another sperm from fertilizing the egg

-Soon, chromosomes will replicate and align before beginning the first mitotic division

Question 4

Blastocyst

Answer 4

Composed of an inner cell mass that differentiates into the fetus and an outer layer of trophoblasts that will form the placenta

Question 5

Syncytiotrophoblast

Answer 5

Formed after the trophoblast destroys the zona pellucida; secretes proteases to digest the endometrium and stroma facilitating implantation

*Invasion is limited by protease-inactivating enzymes deeper in the endometrium

Question 6

Decidua

Answer 6

Endometrium of the pregnant uterus; involves the transformation of stromal fibroblasts into secretory cells filled w/ glycogen and lipids

• Decidua is more edematous than the normal endometrium
• Formation mediated by maternal progesterone and implantation

Question 7

hCG

Answer 7

Secreted by cells of the syncytiotrophoblast to prevent luteolysis and secrete progesterone

*Actually reacts w/ the LH receptor due to similar structure

Question 8

Progesterone (pregnancy secretion)

Answer 8

Primarily made by the placenta after the 8th week; fnxns to:

Inhibit uterine contractions

Form a viscous, mucous plug @ the cervix

Prepare the endometrium for implantation

Question 9

Estrogens (during pregnancy)

Answer 9

Primarily synthesizes E3 @ the placenta from DHEA produced by the fetal zone of the adrenal gland

• Fnxn to increase uterine blood flow, increase LDL uptake by syncytiotrophoblast, and induce mammillary growth
• Syncytiotrophoblast converts DHEA to androgen and then to estrogen

Question 10

hCS

Answer 10

Chorionic somatomammotropin is also called hPL and stimulates lipolysis and antagonizes insulin

Question 11

Relaxin

Answer 11

Inhibits uterine contractions; relaxes the uterine tissue during delivery

Question 12

hGH-V

Answer 12

Placental form of GH; predominates during pregnancy and stimulates negative feedback of normal GH release thru IGF-1 production

Question 13

Breast Development during pregnancy

Answer 13

Requires: 1. Prolactin

2. hPL
3. Estrogen (will further promote PRL synthesis)
4. Progesterone

Permissive effects => GH, IGF-1, insulin, cortisol

Question 14

Mechanism of PRL receptor

Answer 14

JAK/STAT protein => synthesis of B-casein and secretion of milk into the alveolar ducts

*PRL released in response to suckling

Question 15

Initiation of lactation

Answer 15

Occurs due to falling levels of progesterone after pregnancy

Question 16

Oxytocin

Answer 16

Acts on myoepithelial cells to induce ejection of milk

• Occurs in response to suckling (physical) and infant cries (psychological); absence of these will lead to milk buildup and pain
• Works via a Gq pathway

Question 17

Oxytocin clinical uses

Answer 17

1. Induce labor
2. Enhance contractions
3. Decrease postpartum bleeding

Question 18

Lactational Amenorrhea

Answer 18

Suppression of the menstrual cycles from child feeding; could occur due to:

PRL inhibiting GnRH release

OR

Suckling inhibiting GnRH release

Question 19

Actions of E2 on the Female Reproductive Tract

Answer 19

Increase contraction of smooth muscle in the fallopian tubes, the ciliated epithelium of the fallopian tube, the smooth muscle of the uterus, and increases the glycogen content of the uterus

Decreases the pH