Female Physiology (Smith) - week 5 Flashcards
(29 cards)
What type feedback is the most common homeostatic control mechanism?
Negative feedback loop
-occurs primarily at the hypothalmic level
Give an example of a positive feedback loop
Oxytocin during child birth
What does HPO refer to
Hypothalamic Pituitary Ovarian Loop
Where is Gonadotropin releasing hormone (GnRH) released from?
Released from Hypothalamus
What does the anterior pituitary gland secrete?
- FSH
- LH
Name the 3 ovarian hormones
- Estrogens
- Progesterone
- Inhibins
All 3 are target hormones
What does estradiol (E2) feedback do?
Inhibits both the anterior pituitary & hypothalamus
What inhibits FSH secretion?
Inhibin B (also released by granulosa cells)
How are granulosa cells stimulated and what do they produce?
Thecal cells (found in ovary) release androgens which stimulate GRANULOSA cells
Function - produce estrogen
What do LH & FSH stimualte?
LH - Thecal AND Granulosa cells
FSH -Only granulosa
Which type of natural estrogen is predominant during reproductive years?
Estradiol (E2)
Name the 3 natural estrogens and say when they are predominant
- Estrone (E1) - Post menopause
- Estradiol (E2) - Reproductive years (NOT) while pregnant
- Estriol (E3) - While pregnant
Which one of these is NOT a physiological function of estrogen?
a. reduce rate of bone re-adsoprption
b. stimulate endometrial proliferation
c. enhance blood coaguability
d. decrease CNS excitability
e. Increases HDL & Triglycerides
d. decrease CNS excitability
It INCREASES
Name the 2 phases of the menstrual cycle
Follicular phase
(menses & proliferative phase)
Luteal phase
(secretory phase)
Exaplain the hormonal changes during the menstural cycle
- Menses- estrogen is low = GnRH release –> stimulates anterior pituitary to secrete FSH & LH
- FSH & LH stimulate growth of ovarian follicles
When are LH levels the highest?
Middle of menstrual cycle in between follicular phase & luteal phase
When are Estrogen levels highest? Progesterone?
Middle of ovulation
middle of secretory phase
What causes the LH surge?
Peak E2 levels cause a change from negative to positive feedback
so E2 causes a release of MORE GnRH which stimulates the anterior pituitary to release a surge of LH it had stored up
What does this LH surge cause?
Triggers follicle to rupture (ovulation)
Why isnt there a second ovulation event?
Because progesterone inhibits pituitary release of LH & FSH
What happens if egg is not fertilized?
Degeneration of corpus luteum to Corpus albicans and shedding of uterus
All of these are effects of progesterone EXCEPT
- increase fat deposition
- decrease CNS excitability
- decreases body temp
- decreases PCO2 during pregnancy
-decreases body temp
INCREASES body temp
What must happen to a girl before puberty can occur?
They must reach a critical body weight
Why would hCG be released into the body?
Upon implantation, trophoblas cells release hCG
hCG- prompts corpus luteum to continue to express estrogens and progesterone
This prevents further menstration
