Physiology of Female Reproductive System Flashcards
Follicular structures
Premodial follicle-> Primary follicle-> Secondary follicle-> Graafian follicle
Of the two layers of theca cells, which makes the most hormones?
Theca interna
Progesterone is made from which cells?
Granulosa lutein cells
When is the corpus luteum formed?
After ovulation
- The antum collapses, granulosa cells becomes granulosa lutein cells and theca cells become theca lutein cells
NOTE: The follicular fluid contains a lutenization inhibitor which inhibits most of the the luteinization before the ovulation. Once the cell loses follicular fluid, we lose inhibition of the conversion of the luteinization state.
What are the two phases of follicular growth?
- Stimulated
- Regulated by gonadotropins and terminates in atresia or ovulation.
- Tonic or Basal
- Before LH and FSH appear
NOTE: Each month about 100 follicle begin stimulate growth with 20 reaching a larger size
What are the major characteristics of the early follicular growth phase?
- Rising GnRH leads to increased FSH and LH
- Increased FSH leads to increased follicular growth, aromatase, LDL and LH receptor
- NOTE: We get 30% of cholesterol from plasma LDL
- Increased LH leads to increased androgen production and vasculatization of the theca interna region
What are the major characteristics of the late follicular growth phase?
- LH acts on granulosa and thecal cells, FSH acts on granulosa cells
- Follicular fluid characterized by elevated levels of estradiol, progestins, LH and FSH but low androgens
- Atretic follicles charachterized by elevated androgen levels
Aromatase is an important enzyme in ______ synthesis.
Estrogen
Elevated levels of ____ can be expected when we stop making P450 aromatase.
Androgens because we stop converting androgens to estrogens.
Ovarian steroid synthesis
When we stimulate the follicle with LH, it stimulates the induction of more ______ protein into the mitochondria membrane.
StAR
NOTE: Cholesterol cross the mitochondria membrane via the StAR protein. Once in the mitochondria, cholesterol is converted to pregenelone via the P450 side chain cleavage enzyme.
What are the two hormones that can be converted to estradiol?
Estrone and testosterone
NOTE: Cholesterol-> Pregenolone-> Progesterone-> 17-hydroxyprogesterone-> androstenedione->estrone-> ESTRADIOL
-OR-
Cholesterol-> Pregenolone-> Progesterone-> 17-hydroxyprogesterone-> androstenedione-> testosterone-> ESTRADIOL
Which two cell types are required for the synthesis of follicular estrogen?
Theca cells
- Synthesize androgens
- Stimulated by LH
-
Leads to induction of enzymes needed for andostenedione synthesis
- Andostenedione diffuses into the granulosa cell
-
Leads to induction of enzymes needed for andostenedione synthesis
Granulosa Cells
- Convert androgens to estrogens
- Stimulated by FSH
- Leads to induction of P450 aromatase
What is the role of SF1?
SF1 is a nuclear receptor that stimulates StAR in mitochondria membrane
__________is a preadipocyte-specific nuclear receptor that regulates expression of aromatase in adipose tissue.
LRH-1
The _________, a cone shaped protrusion of the follicular wall, appears just prior to ovulation.
Stigmata
What events take place right before ovulation?
- Appearance of stigmata
- Follicular fluid has elevated estrogen, prohgestins, FSH, LH, oxytocin, plasmin and collagenase activity
- Plamin degrades the basal lamina
- Collagenase cleaves adhesive proteins
- Extensive vascularization
NOTE: These events help to weaken the follicle and prepare it for ovulation.
Myoepithelial cells located around the basal lamina are stimulated by ________.
Oxytocin
NOTE: Oxytocin promotes contractions and it builds up in the follicular fluid prior to ovulation.
If we properly weaken the area of the stigmata, we then eject an oocyte with cumulus complex, freeing it from the rest of the follicle. The rest of the follicle becomes the _________.
Corpus luteum
Which enzymes serve to digest the follicular wall and weaken granulosa cell adhesion?
- Collagenase
- Plasmin
NOTE: The wall gives way at the weakened area forming the stigmata
What are the 3 phases of corpus luteum development?
- Early luteal phase
- Advanced Luteal Phase
- Late Luteal Phase
NOTE: FSH has no direct role in corpus luteum maintenance
What occurs during the early luteal phase?
- LH stimulates thecal and granulosa cell growth
- LH induces luteinization of both cell types and subsequent growth of luteinized cells
- Progesterone synthesis increases as the number of luteal cells increase
What occurs during the advanced luteal phase?
- LH stimulates increased estrogen and progesterone synthesis
- Corpus luteum function depends on adequacy of follicular development before ovulation
- FSH induction of adequate LDL receptor and LH receptor levels before ovulation assures sufficient steroidogenesis by the corpus luteum
- Inadequate CL production of progesterone leads to luteal insufficiency
NOTE: FSH has no direct role in corpus luteum maintenance
What occurs during the late luteal phase?
- Estrogen enduces luteolysis
- Luteolysis leads to decreased plasma progesterone and estrogen
- Luteolusis process continues in absence of fertilized ovum
What is different about steroid synthesis in the follicular phase and steroid synthesis in the luteal phase?
Follicular phase
- Granulosa cells stimulated by FSH
Luteal phase
- Granulosa cells stimulated by LH
Inhibin, activin, and follistatin are secreted by the ____ of the testes and the ______ cells of the ovaries.
Sertoli; granulosa
Inhibin
Feedback from gonads to the anterior pituatary and suppress secretion of FSH
Activin ________ (stimulates/inhibits) FSH secretion.
Stimulates
Folistatin binds to ____ and blocks its activity on pituatary gonadotropes to reduce FSH secretion.
Activin
Which estrogen type has the most estrogenic activity?
E2- 17 betaestradiol
What affect does estrogen have on the ovaries?
Increase function
What effect does estrogen have on the uterus?
- Increased growth
- Increased endometrial growth
What effect does estrogen have on the fallopian tubes?
- Increases overall growth
- Increases mucosal growth
What effect does estrogen have on the breasts?
- Increases growth and development
- Increased fat deposition
- Increased stromal cell growth
- Increased ductile system development
NOTE: Estrogen increases growth and progestorone increases secretion
What are the phases of the uterine cycle?
Proliferative phase
- Growth of stromal and epithelial cells as well as blood vessels
- Via estrogen produces
Secretory phase
- Glands become convoluted, secretion greatly increases, growth continues.
- Estrogen and progesterone are being produced
What are the stages of the cervical cycle?
-
Early follicular cycle
- Low mucus volume and elasticity, high viscosity
-
Late follicular phase
- Increased mucus volume and elasticity, decreased viscosity
-
Luteal phase
- Similar to that of the early follicular phase
- Progesterone blocks the activity of estrogen
What are the two kinds of secretion of the cervix?
Surface mucus cells
- Make a really thick mucus
- Prevents things from goin gin and out
Endometrial glands
- Makes a thin high protein secretion
- High protein leds to elasticity
- Allows spermatozoa to go in
NOTE: Estrogen stimulates cervical gland secretion
Follicular phase in ovary= __________ phase in uterus.
Proliferative
Luteal phase in ovary= __________ phase in uterus.
Secretory phase
What are the phases of the vaginal cycle?
Early follicular
- Predominenately basophilic cells
- Decreased volume; increased viscosity
Late follicular
- Predominately cornified cells
- Increased volume, decreased viscocity
Luteal
- Decreased cornified cells, increased polymorphonuclear neutrophils
- Decreased volume, increased viscocity
What are the phases of the adult menstrual cycle?
Follicular phase
- Post-mentrual, proliferative, estrogenic
- Follicular maturation
- Proliferative endometrium
Luteal phase
- Premenstrual, secretory, progestational
- Corpus Luteum Activity
- Secretory endometrium
Rise in basal body temperature is induced by _______.
Progesterone
Estrogen peak in the follicular phase is the result of a switch to ___________ feedback regulation of the gonadotropins.
Positive
Inhibin B is produced mainly by the ___________, while inhibin A is derived mainly from the __________.
Follicle; Corpus luteum
The B version inhibits FSH
The major androgen from thecal cells is __________.
Androstenedione
What accounts for the LH surge?
Positive feedback regulation from LH and FSH, stimulate the hypothalamus to release GnRH, which stimulates LH release.
NOTE: FSH is inhibited by inhibin B, which is why there is no FSH surge to accompany the LH surge
A ________ secretion of GnRH is required to stimulate pituatary secretion of gonadotropins.
pulsitile
NOTE: If we give the pituatary a tonic signal, it shuts down and stops secreting.
What are the three patterns of gonadotropin secretion in women?
Chichoral
- High frequency changes occuring at 1-5 hour intervals
Diurnal
- Intermittent frequency changes occuring across a 24-hr period
Trigintan
- Low frequency changes occuring across a 29-30 day period
Estrogen feedback supresses the ______ (amplitude/frequency) of gonadotropin pulses. Progesterone feedback supresses the _______ (amplitude/frequency) of gonadotropin pulses.
Amplitude; frequency
What levels of estrogen trigger a switch to positive feedback control?
>300 pg/ml for >24 hours
What are the major types of oral contreceptives?
Estrogen-progesterone
- Suppresses ovulation and supports secondary sex organ function
- Used to regularize cells in some subjects
Progesterone mini pill
- Blocks estrogen induced cervical mucus changes
The estrogen “morning after” pill
- A high dose estrogen treatment
- Believed to function by interfering with implantation
- It is believed that the implantation site is chosen by the level of estrogen at the site
NOTE: Oral contraceptives suppres the cyclical pattern of all major reproductive hormones
Addition of _________ increases plasma half-life of oral contreceptives.
Ethinyl group
Non-oral contraceptives
Progestin Type
–Injection
- Depo-provera (methoxy progesterone)
- Effective for three months
–Implant
- Norplant (levo norgestrel)
- Effective for up to five years
Effects of oocyte aging
- Increased incidence of birth defects
- Increased downs syndrome
- Increased Klinefelters Syndrome
- Increased incidence of spontaneous abortion
What is the main cause of hirsutism?
Main cause is increased ovarian and/or adrenal androgen secretion
*Can be exacerbated by TeBG responses
