Lecture 17: Reproduction 5 Flashcards
What two things produce RELAXIN? In response to what?
What are its 2 major functions?
- Placenta & corpus luteum
- In response to HCG
1) Inhibits myometrial contractions (ensure uterine quiescence in early pregnancy)
2) Relaxes pelvic bones and ligaments and softens cervix (may play a role in parturition)
Prolactin is produced from the placenta. True or False?
Essential for mammotrophic effects of _____ and _______
It stimulates lactogenic apparatus during gestation, but significant lactation is inhibited by high levels of what 2 hormones?
What stimulates growth of the lactotrophs and increases PRL secretion?
FALSE
from maternal pituitary
- estrogen
- progesterone
high levels of progesterone and estrogen
ESTROGEN
What clinical syndrome can occur due to infarction of the pituitary (large lactotroph growth and ischemia can occur if hemorrhage)
SHEEHAN’s SYNDROME
Levels of _____ remain high during gestation to stimulate the corpus luteum.
What begins producing progesterone & estradiol in the 2nd two trimesters?
What other hormones are increasing?
- HCG
- Placenta
- Chorionic Somatommamotropin & Prolactin
Placenta
Has limited capacity to synthesize cholesterol and
relies almost exclusively on maternal _____
as cholesterol source.
Major site of estrogen synthesis, even though it
lacks _______ activity, which converts
progesterone to androgens and estrogens.
- LDL
- 17,18 desmolase
- Uses androgenic substrates from mother and fetus
to synthesize estrogens
What is the major source of Fetal Estrogens (conversion of pregnenolone to DHEA-S)?
Conjugation of sulfur to DHEA makes it more _____ but also less ______.
- Fetal zone of adrenal gland (fetal adrenal is 20X larger)
2. more water soluble, less bioactive
DHEA diffuses back to ____ where both cytotrophoblast and syncytiotrophoblast have abundant sulfatase and aromatase activity resulting in the production
of what?
What hydroxylates DHEA-S in the 16 position?
Where does this then diffuse where the sulfate group is removed and it is aromatized to ESTRIOL?
- placenta, ESTROGEN
- FETAL LIVER
- PLACENTA
Estriol is only made from maternal ovaries or adrenal glands.
True or False?
What can this serve as a parker of?
FALSE
- only made in the FETAL LIVER PRECURSORS not from maternal ovaries or adrenal glands
- Marker of fetal well - being
- Weak estrogenic activity
**
Although estriol is the major estrogen of pregnancy, it has weak estrogenic activity.
State the many functions of PROGESTERONE. (6)
Which is the most important?
How do high levels of E2/Progesterone affect lactogenesis?
- Inhibits uterine contractions
- Inhibits PROSTAGLANDIN production
- Decreases sensitivity to OXYTOCIN
- Upregulate B- Adrenergic = myometrial relaxation
- Decreases T cells & macrophage fx.
- Reduce # of leukocytes
- MAMMOGENESIS
- stimulates alveolar pouches of mammary glands
- increase in their capacity to secrete milk
E2/Progesterone preven lactogenesis (occurs after birth)
What are the 5 actions of estrogen?
- MAMMOGENESIS (promotes growth of ductal system of breast)
- Continuous growth of myometrium
- w/ Relaxin, softens pelvic ligaments and symphysis pubis
- Enlargement of external genitalia
- Late gestation involved in parturition
What happens when the ratio of progesterone to estrogen is the following:
- Progesterone»_space; estrogen
2.
Estrogen»_space; progesterone
- Progesterone»_space; estrogen
maintains uterine quiescence and sustenance of fetus - Estrogen»_space; progesterone
may play an essential role in parturition
What are 3 ways to prevent fertilization?
- Abstinence
- Coitus Interruptus
- Barries (condoms, diaphragms, and cervical caps in combination with spermicides)
What are the actions of contraception? (7)
- Prevent LH surge and ovulation
- Decrease basal gonadotropin levels
- inhibit FOLLICULAR growth
- Fallopian tube motility is decreased (in vitro observation)
- Glandular atrophy in uterine endometrium
- Inhibits implantation of blastocyst
- Causes thick cervical mucus – inhibits sperm motility and migration
What hormone prevents LH secretion? (blocking LH surge)
What inhibits FSH release?
- progesterone
- Estrogen
- stabilizes endometrium and potentiates progestin action
What are the benefits of contraceptives? (4)
Risks/side effects? (4)
Non-Contraceptive Benefits
- Treatment of excessive menstrual bleeding
- Protection for pelvic inflammatory disease
- Dysmenorrhea (decreases thickening of endometrium and amount of bleeding during sloughing)
- Hormone replacement therapy in postmenopausal women
Risks and Side Effects
- Contraindicated in heavy smokers over 35 and those with a history of estrogen-dependent breast carcinomas
- Hypertension, myocardial infarction, stroke
- Depression
- Decreased libido
What are the cardiovascular changes during pregnancy? (3)
- Why does the Mean Arterial pressure decrease?
- Increased Cardiac output, HR, and Stroke volume
- Catecholamines mediate chronotropic (HR) and inotropic (contractility)
- Cardiomegaly (reversible)
- TPR decreases more than CO increases
What pressure stays the same during pregnancy?
What pressure increase?
How does blood flow change? (3)
How does RBC and Plasma change?
- Pulmonary pressure stays the same
- Venous pressure increases
- a) -Uterus may receive 30% of cardiac output
b) - skin blood flow increases
c) GFR increases
Plasma and RBC increase with a net decrease in hematocrit
RESPIRATORY CHANGES:
- Increase in ______with no change in _______
- Increase in _____ ventilation
- hyperventilation leads to respiratory _____ which is compensated for by renal _____ excretion
- tidal volume; frequency
- alveolar
- alkalosis, bicarb
How does GI change? (2)
What happens to the Hypothalamic - pituitary - gonadal axis?
Pituitary _____ growth and an increase in what hormone secretion?
- decrease in GI motility to increase nutrient absorption
- DECREASE IN LES TONE = greater reflect during pregnancy
- Axis is suppressed by high concentrations of placental sex steroids
- Lactotrophs/Prolactin secretion increases
How does the first and second half of pregnancy differ in terms of anabolic/catabolic states?
Which is characterized by insulin sensitivity/resistance?
Which releases HPL?(human chorionic somatomammotropin )
What two vitamins are extremely important and why?
- First half of pregnancy - mother is in anabolic state **
- Normal/ increased sensitivity to insulin
- Increased fat deposition, glycogen stores
- Promotes breast growth in mom to store nutrients for demands of fetus
- Second half: CATABOLIC
- INSULIN RESISTANCE
- mediated by Human Chorionic Somatomammotropin
- increased plasma glucose and fatty acid levels - Folic Acid –> Vitamin B9
- reduces neural tube defects and spina bifida
Vitamin K
- fetal livers not good at utilizing Vitamin K needed for blood clotting
- give injections after birth to prevent hemorrhage
What are the following hormones extremely important for?
- Progesterone
- E2
- Cortisol
- RELAXIN
- Oxytocin
- CRH
- Prostaglandins
- Catecholamines
What is the most dominant?
PARTURITION
** most dominant = decrease in progesterone and increase in estrogen***
Which hormone simulates the following:
- myometrial quiescence
- Cervical rigidity
Which hormone mediates the following:
- Myometrial gap junctions
- Myometrial activation
- Prostaglandins and E production
- Local OXYTOCIN production
- Cervical Ripening (distend and open)
- Progesterone
2. ESTRADIOL
What hormone has a role in precipitating labor?
How does it affect the timing of gestation?
What does it potentiate?
What hormone does it increase?
What is the localized positive feedback in relation to the placenta and fetus?
CORTISOL
- absence of HPA axis = prolonged gestation
- no cortisol surge but CRH levels peak during pregnancy at labor
2. If CRH is high early in gestation, decreased gestation time
3. Potentiates contracture response to prostaglandins and oxytocin
4. CRH from placenta and fetus increase E2!!!
5. Fetal cortisol amplifies placental CRH synthesis (localized positive feedback). - -Braxton Hicks contractions -“false labor” –> to prepare the uterus for true labor
What does the decrease in the progesterone/E2 ratio lead to?
What does this then increase?
Result?
- increased local prostaglandins
- Myometrial cell Calcium
- More forceful myometrial cell contractions
Oxytocin is a 9 AA peptide from where?
What receptor does it bind and explain the series of steps that lead to INCREASED UTERINE SM contractions
What hormone increases the number of OT receptors in myometrial tissues in pregnancy?
What is the uterine sensitivity to OT? (when does it increase 200 fold)
- Posterior pituitary (PVN and SON)
- bind Gq receptor in myometrial tissue
- PLC results in increased IP3
- INCREASED CALCIUM
- Ca- Calmodulin
- MLCK
- INCREASED UTERINE Smooth muscle contractions
- ESTROGEN increases the number of OT receptors in myometrial tissues in pregnancy
= increased potency to OT - Uterus is insensitive to OT until 20 wks
- then sensitivity gradually increases to 80 fold at 36 weeks,
- plateaus just before parturition,
-and then increases to 200 fold in early labor
When is OT released?
What is the Ferguson reflex? (TEST TEST)
OT stimulates _____ release, which also stimulates contractions.
- Once labor begins
- -> increased frequency throughout - Distension of the cervix causes maternal OT release!!!!
- prostaglandin
Additional affects of OT:
- Promotes hemostasis of expelled placenta vessels.
- It may also enhance emotional bonding
E2 and prostaglandins increase alpha or beta adrenergic receptors? (what is the purpose of this?)
What increases catecholamines?
- ALPHA
- stimulates myometrial contraction - MATERNAL STRESS
State what happens during the 3 stages of labor.
What happens once the placenta is gone? (significant)
1st - several hours, widening and thinning of cervix
2nd -
What is one extremely important function of CORTISOL in the fetus?
INCREASES PULMONARY SURFACTANT
– if pre-term labor, can give a fetus glucocorticoid injection to increase expansion of fetal lungs (via surfactant)
When is lactation initiated?
What stimulates prolactin?
What does it suppress?
What is an important behavior that it stimulates? (test)
- AFTER DELIVERY: decreased progesterone and E2
- SUCKLING stimulates prolactin
- Prolactin suppresses reproductive function (inhibits GnRH)
- prolactin stimulates maternal behavior during pregnancy and after parturition
What is the name of the first milk that is produced and what does it consist of?
What about later breast milk?
- CLOSTRUM
- contains little fat
- HIGH PROTEIN
- and immune cells - low in protein, 7% lactose, 5% fat, LARGE AMOUNT OF HORMONES
WHat 3 hormones are essential for continued milk production?
What is released in response to neural input to NTS (mother’s response to infant crying) ?
What is the function of this hormone?
Does it have mammogenic and galactogenic effects? If not, which one does?
- Prolactin
- Cortisol
- Insulin
- OXYTOCIN
- Contraction of myoepithelial cells and alveoli and smooth muscle of duct walls causing “milk let down”
- NO - PROLACTIN is
mammogenic (breast development)& galactogenic (milk production)
OXYTOCIN ONLY RELEASES MILK, it does NOT make the milk
What does the stimulus of SUCKLING at the breast result in? (2)
- Prolactin release to promote continued milk production
2. OXYTOCIN stimulates breast for milk ejection
DURING SUCKLING:
Afferents from spinal cord inhibit _____ release from arcuate n.
which removes inhibition that it normally has on _____ in ant pit, causing ______ release to promote milk production.
- Dopamine
- lactotrophs
- prolactin
What stimuli (neural input) are responsible for the release of oxytocin?
What nuclei is it released from?
What does released oxytocin stimulate?
What does this neural input inhibit?
- AFFERENT VISUAL and AUDITORY sensation
- -> seeing and hearing the baby cry - PVN and Supraoptic Nuclei
- Released oxytocin stimulates breast to contract structures to enhance milk ejection – “letdown”.
4.Inhibit arcuate N. and Preoptic Area causing a decrease in GnRH
with reduced output of gonadotrophs
= increase amount of time to take care of baby before the next one arrives
