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What are the erectile tissues that contribute to the female sexual response?
Corpus cavernosum

Frendulum clitoridis

Glans clitoridis

Crus clitoridis

Bulbus vestibuli
What are the contractile tissues that contribute to the female sexual response?
Ischiocavernosus muscle

Labium minus

Vagina
What are the secretory tissues that contribute to the female sexual response?
Bartholin's gland
What roles do the sympathetic and parasympathetic nervous systems play in female sexual arousal and orgasm?
Arousal: parasympathetic

Orgasm: sympathetic
On what hormone do sexual secretions depend?
Estradiol
What impedes blastocyst movement into the uterus from the fallopian tube and what eventually enables this passage?
The isthmic/ampullary junction contracts because of estradiol

Progesterone relaxes this muscle
What is decidualization of the uterus?
Increased capillary hypertrophy and permeability
When in the menstrual cycle does implantation occur?
Prior to the time of the menstrual period
From which tissue does the placenta form?
Fetal trophoblastic cells
How does the trophoblast differentiate?
Inner layer of cytotrophoblasts

Synctiotrophoblast from fused cytotrophoblasts
What does hemochorial mean in the instance of pregnancy?
The chorion is bathed in maternal blood
What hormones does the syncytiotrophoblast secrete?
hCG

hCS

hGH-v

Estradiol

PTH-RP

Progesterone

CRH
How does fetal blood become oxygenated and remove CO2?
In the placenta, maternal blood exchanges oxygen with fetal blood through diffusion

CO2 moves down its concentration gradient from fetal blood to maternal blood
From where and when is hCH secreted?
Trophoblasts

Syncytiotrophoblast (after placenta develops)

Prior to implantation
What are the major roles of hCH?
Prevents the shedding of the endometrial lining

Rescues corpus luteum
- Binds LH receptors
- Maintains progesterone and estradiol production
How does hCH differ from LH?
Longer beta subunit

Highly glycosylated

Longer half life
How do hCG and progesterone levels change when compared to before and after the LH surge?
What is the luteal-placental shift?
The shift to the placenta becoming the major steroidogenic tissue from the corpus luteum producing progesterone and estradiol from hCG binding after 8 weeks
What does relaxin do and where is it made?
Softens the cervix

Made by the corpus luteum
Which tissue makes human chorionic somatomammotropin (hCS) and what are its major actions?
Made by the placenta

Stimulates maternal liver to use fats instead of glucose to save glucose for the fetus
Which tissue makes placental GH (GH-V) and what are its major actions?
Made by syncytiotrophoblasts

Enhances mother's ability to use non-glucose fuels
Why is fetal insulin important?
Regulates fetal glucose utilization

Regulates liver glycogen storage

Regulates fat deposition
Which tissue secretes prolactin and what are its main actions?
Made by the maternal pituitary, uterine decidual cells (maternal half of placenta,) fetal anterior pituitary

Promotes growth and differentiation of mammary tissues
How do levels of hCG, hCS, and prolactin change throughout pregnancy?
How do the effects of progesterone and estrogens counteract each other throughout pregnancy?
Progesterone:
- Relaxing action on myometrial cells

Estrogens:
- Contraction promoting on myometrial cells
What tissue secretes cortisol and what are its major actions?
Picked up from maternal circulation but then made in the fetal adrenal glands halfway through pregnancy

Major role in:
- Heart development
- Lung development
- Production of brown fat
- Deposition of glycogen
What are the three estrogens secreted by the placenta during pregnancy?
Estrone (E1)

Estradiol (E2)

Estriol (E3)
How do progesterone, estrogens, and cortisol levels change throughout pregnancy?
What tissue secretes corticotropin-releaseing hormone (CRH) and what are its major actions?
Secreted by the placenta
- Placental CRH stimulate:
- Fetal ACTH secretion
- Adrenal synthesis of androgen and cortisol

Secreted by hypothalamus (non-pregnant)
- CRH stimulates the secretion of pituitary ACTH (which stimulates adrenals to make cortisol)
How are the levels of CRH mediated throughout pregnancy?
CRH is bound to maternal CRH-binding protein (CRH-BP) throughout the early pregnancy

This inactivates CRH
What kind of feedback mechanisms impact CRH levels during pregnancy?
Positive feedback:
- Placental CRH stimulates the fetal adrenal to secrete cortisol
- Fetal cortisol stimulates placental CRH production

Positive feedback:
- CRH stimulates endometrial prostaglandin synthesis
- Endometrial prostaglandins stimulate placental CRH
How do the levels of CRH and CRH-BP change throughout the course of pregnancy?
What might elevated levels of CRH early in pregnancy suggest?
Pre-term labor
What are major fetal androgens and what is their major source during pregnancy?
DHEA, testosterone, androstenedione

Fetal adrenals

Maternal adrenals (lesser extent)

*No ovarian or placental androgen synthesis*
What is the importance of fetal androgens?
Precursor to estrogen synthesis

Male sexual differentiation
How do levels of fetal androgens change over the course of pregnancy?
Describe the synthesis of steroidogenesis in pregnancy
1. Placenta takes LDL from maternal liver and converts it to pregnenolone

2. Pregnenolone is converted to:
- Progesterone (placenta)
- DHEA-S (fetus)

3. DHEA-S is converted to:
- 16α-OH-DHEAS (fetal liver)
- DHEA → Androstenedione (placenta)
- Estrone
- Estradiol
- Estriol
How do levels of progesterone and estrogens change throughout pregnancy?
Early, progesterone effects dominate (supported by estrogens)

Later, as birth approaches, estrogen effects predominate
- Promote uterine contractions
How do fetal and maternal estrogens aid progesterone synthesis throughout pregnancy until birth?
Stimulate placental LDL uptake

Stimulate P450cc
How does the predominating role of estrogen increase uterine contractility?
- Increases sodium, potassium, and calcium channels in SM

- Increases sensitivity to adrenergics

- Increases oxytocin receptors

- Increases prostaglandin receptors and synthesis
What is the main role of fetal adrenals during pregnancy?
Secrete DHEA (precursor to estrogen)

Secrete cortisol
What are the zones of the developing fetal adrenal and what do they secrete?
Fetal zone (inner):
- Androgen
- ACTH in response to maternal and placental CRH, making cortisol

Definitive zone (outer):
- Zona glomerulosa (outer): aldoesterone
- Zona fasciculata (middle): cortisol, DHEA
- Zona reticularis (inner): androgens
What does the fetal medulla secrete?
Epinephrine

Norepinephrine
What does fetal cortisol stimulate?
Fetal Lung surfactant

Fetal liver enzymes

Intestinal function

Closure of ductus arteriosus
What is lecithin, where is it found, and why are lecithin levels important?
Surfactant indicator in amniotic fluid

Levels indicate lung maturation in terms of surfactant production
Where are fetal corticosteroids found?
Umbilical cord plasma
How do fetal corticosteroid, lecithin, and liver glycogen levels change throughout pregnancy?
Describe how CRH affects the onset of parturition
1. CRH increases estrogen synthesis

2. Progesterone:estrogen ratio shifts towards estrogen

3. Estradiol increases prostaglandin production

4. Estrogens and CRH increase myometrial oxytocin receptors, prostaglandins, alpha-adrenergic catecholamines

5. Increased intracellular calcium induces contractions

6. Contractions stimulate oxytocin release from the posterior pituitary

7. Positive feedback
What hormones promote parturition and how?
Oxytocin: bind to myometrial receptors

Prostaglandins: increase intracellular calcium

Catecholamines: stimulate smooth muscle contraction

CRH: direct stimulation of contraction or increases ability of myometrium to respond to other hormones
How do gap junctions play a role in myometrial contractions?
Coordinate simultaneous contractions