2.4.1 Physiology of the Placenta

Question 1

What is the functional role of invasive cytotrophoblasts?

Answer 1

Tap into the maternal vasculature (spiral arteries) after week 12 of gestation

Decidua assists in controlling the depth of invasion

Prior to this the placenta and developing fetus is somewhat hypoxic

Nutrient and waste exchange can then occur across the syntial layer of the placenta.

Question 2

Describe how these hormones (estrogen, progesterone, insulin, GCs, Prl GH PL, and oxytocin) affect mammary gland development

Answer 2

Question 3

Identify the components of implantation

Answer 3

Question 4

What allows the placenta to produce estradiol?

Answer 4

DHEA from the fetal adrenal

Question 5

Describe the production of CG (CG levels) throughout pregnancy

Answer 5

Question 6

What type of blood?

Answer 6

Maternal blood

Question 7

What are the three steps of cytotrophblast remodeling?

Answer 7

1. Cytotrophoblast invasion of spiral arteries
2. Maternal blood bathes placental villi
3. Nutrient exchange across villi

Question 8

(Blastocyst) Invasion and remodeling of the hypoxic environment occur during what time period of the pregnancy?

Answer 8

The first 12 wks

Question 9

What are the four roles of decidualization?

Answer 9

controls invasion, nutrition, prevents immune rejection, Prl secretion

Question 10

What hormones are produced by the syncytial layer (Syncytiocytotrophoblasts)?

Answer 10

Chorionic Gonadotrophin (CG)

Placental Lactogen (PL)

Progesterone

Estrogens

Question 11

What cellular connection aids in myometrial contractions?

Answer 11

Gap Junctions

Question 12

Which hormone is responsible for preparing the uterus for implantation?

Answer 12

Progesterone

Question 13

Describe how maternal circulating levels of pituitary GH (GH1), placental GH (GH2), and IGF during pregnancy change.

Answer 13

Question 14

What are the roles of PL?

Answer 14

Regulates metabolism, stimulating the conversion of glucose into FA’s and ketones, stored as fuels, promotes maternal mammary gland development

Question 15

What is a major stimulator of oxytocin in milk propulsion?

Answer 15

Suckling

Question 16

What is this an image of? What are the two roles of syncytiotrophoblasts?

Answer 16

Placental villi (floating)

Roles: Transport, endocrine

Question 17

What is the role of CG?

Answer 17

Binds to LH receptors and stimulates progesterone production by Corpus Luteum

Question 18

How does the production of PL change during the course of a pregnancy? (red)

Answer 18

Question 19

CG regulates the synthesis and secretion of __ from the corpus luteum

Answer 19

P4

Question 20

What changes occur in the functional and structural phase of luteolysis? (4)

Answer 20

Changes in: sensitivity to LH, blood supply, P4 and E2, leads to apoptosis

Question 21

What two hormones play a role in lactation?

Answer 21

Prolactin - milk secretion

Oxytocin - propels milk

Question 22

Describe placental steriodogenesis as it relates to the fetus and producing products for maternal circulation

Answer 22

Question 23

What are the roles of relaxin, estrogens, prostaglandins, and oxytocin in parturition?

Answer 23

Question 24

What hormones can be produced by the fetus?

Answer 24

DHEA

Question 25

Describe the phases of menses, follicular, ovulation, and luteal

Answer 25

Question 26

How long does the gamete reside in the Fallopian tube? In the uterus prior to implantation?

Answer 26

* Resides within the oviduct/fallopian tube for approximately 3 days * Resides within the uterus approximately 3 days prior to attachment of the blastocyst to the uterine wall and subsequent invasion. * Therefore, implantation occurs 6-7 days following ovulation.

Question 27

Identify the maturity of the placenta

Answer 27

Left: 1st trimester placenta Right: Full term placenta

Question 28

What is the predominating hormone in the follicular phase? luteal phase?

Answer 28

Follicular: Estrogen Luteal: Progesterone

Question 29

Describe the blood flow to the placenta

Answer 29

High volume and low resistance

Question 30

What are the two goals of the cyclicity of the HPG axis?

Answer 30

1. Prepare a fertilizable oocyte 2. Establish a uterine environment that promotes: * Gamete movement (primarily via Estrogen) * Implantation (Progesterone) * The oocyte is viable/fertile for approximately 18 hr (6-24 hr range) following ovulation

Question 31

What hormones can be produced from cholesterol in the placenta?

Answer 31

P4 NO Androgen synthesis b/c the lack of CYP17 (no estradiol)

Question 33

What is the importance of the early rise of CG?

Answer 33

Rescues the corpus luteum and progesterone production

Question 34

Compare CG and LH (secreted from, acts upon, composition, MW, t_1/2, receptor)

Answer 34

Question 35

What inhibits myometrial contraction? Stimulates it?

Answer 35

Inhibitor: P4 Stimulators: Estrogens

Question 36

What hormones can be produced in the ovary?

Answer 36

P4 and Estradiol

Question 37

Parturition relies on the positive feedback of what?

Answer 37

Oxytocin (leading to greater and greater contractions

Question 38

Increase in secretion of CRH from the placenta stimulates what? (2)

Answer 38

Fetal adrenal DHEA production Prostaglandin production

Question 39

What are the roles of the 4 functional components of the placenta?

Answer 39

Cytotrophoblasts (placental **stem cell** characterisitics) Anchoring villous – Attachment Invasive cytotrophoblasts – Invasion Syncytiocytotrophoblasts – Barrier, Endocrine, Transport

Question 40

What allows the placenta to produce estriol?

Answer 40

16OH-DHEA from fetal adrenal/liver

Question 41

On what side of the villi are the different types of blood?

Answer 41

Top: Maternal Bottom: Fetal

Question 42

Describe the feedback with oxytocin

Answer 42

Question 43

Describe how hormone production occurs b/t the mother, placenta, and fetus. **IMPORTANT**

Answer 43

Question 44

What are the four functional components of the placenta?

Answer 44

1. Cytotrophoblasts 2. Anchoring villous, columns of cytotrophoblasts 3. Invasive cytotrophoblasts 4. Syncytiocytotrophoblasts

Question 45

What inhibits cervical maturation (collagen breakdown)? Stimulates it?

Answer 45

Inhibitor: P4 Stimulators: E, Relaxin, PGE₂

Question 46

Describe how the various levels of estrogen and progesterone change over the course of a pregnancy

Answer 46

Question 47

Which hormone aids in gamete movement?

Answer 47

Estrogen

Question 48

What is circumscribed in blue?

Answer 48

Placenta

Question 49

Describe how the gamete moves and develops as it passes down the Fallopian tube

Answer 49

Question 50

What are the effects of estrogen/progesterone on the uterus? What other sites do these hormones work on?

Answer 50