Module 3B Flashcards
What letters denote male chromosomes?
- XY
What letters denote female chromosomes?
- XX
How is male genitalia differentiated?
- SRY antigen secreted by Y chromosome
- T stimulates Wolffian Duct to develop
- Sertoli cells of testes release MIH (Mullerian-inhibited factor)
- prostate converts T to DHT
What do Wollfian Ducts develop into?
- epididymis
- vas deferens
- seminal vesicle
What is the function of MIH?
- Mullerian-inhibited factor
- prevents Mullerian Duct from forming into genitalia
What is the function of DHT?
- dihydrotestosterone
- stimulates development of scrotum, penis, & prostate
How is female genitalia differentiated?
- No SRY antigen
- no male hormones present
- undifferentiated gonads naturally progress to ovaries
What are the primary male sex organs?
- testes
What is the function of the testes?
- production of spermatozoa
- production of T (testosterone)
What two hormones are required for spermatogenesis?
- T
- FSH
What is the male steroid hormone?
- testosterone (T)
Where is T synthesized?
- Interstitial Cells of Leydig
What are the general effects of T?
- anabolic
- androgenic
What are the anabolic effects of T?
- stimulates GH secretion which leads to IGF-1 release
- end of puberty, promotes closure of growth plates
- stimulates protein synthesis in muscle
- summary - T has direct and synergistic effects on growth*
What are the androgenic effects of T?
- development and maintenance of male accessory sex organs
- differentiation of male reproductive tract and brain
- development of secondary sex characteristics
- libido & potency
What happens to T with age?
- decreases
Where does spermatogenesis occur?
- seminiferous tubules
What happens to the sperm after they are synthesized?
- stored in epididymis
Describe the hormonal regulation of T
- GnRH stimulates FSH and LH from ant. pit.
What does FSH do in the hormonal regulation of T?
- stimulates spermatogenesis in testes
- releases inhibin from testes
What is the function of inhibin?
- inhibits FSH release from ant. pit.
What does LH do in the hormonal regulation of T?
- stimulates synthesis & secretion of T from testes
What inhibits LH?
- increased levels of T
What is the primary female sex organ?
- ovaries
What is the function of the primary female sex organ?
- oogenesis
- produces estrogens & progesterone
What is the function of estrogen?
- prepare for fertilization
- development & maintenance of female secondary sex characteristics
- protective effects on bone metabolism
- positive effect on CV
- CNS influences
What are the two cell types within a follicle?
- theca cells
- granulosa
What hormones do the ovaries produce?
- estrogens
- progesterone
- inhibin
In summary, what is the function of progesterones?
- implantation
- maturation
- maintaining pregnancy
Describe LH’s action during the menstrual cycle
- weeks 1 & 2, LH is required to stimulate ovarian follicle to produce estrogen
- surge at 14 d = LH stimulates ovulation
- weeks 3 & 4 = LH stimulates corpus luteum to release progesterone
Describe FSH’s action during the menstrual cycle
- week 1 & 2 FSH stimulates growth of ovarian follicles and estrogen production
What are the phases of the menstrual cycle?
- follicular phase
- ovulation
- luteal phase
When is the follicular phase?
- days 1-14
When is ovulation?
- day 14
When is the luteal phase?
- days 14-28
What happens in follicular phase?
- endometrium thickens
- ~20 ovarian follicles mature but 1 becomes dominant and other apoptose
What happens during ovulation?
- surge of LH leads to ovulation
- uterus changes to allow sperm to enter
What happens in the luteal phase?
- follicle –> corups luteum
What happens in the luteal phase if fertilization occurs?
- corpus luteum produces hormones necessary for pregnancy
What happens in the luteal phase if fertilization does not occur?
- corpus luteum eventually degenerates
- ischemia of endometrium (menses)
What are the stages of the follicular phase?
- early
- mid
- late
What happens during the early follicular phase?
- GnRH stimulates release of LH & FSH from ant. pit
- LH/FSH stimulate ovarian follicle growth & production of estrogens
- estrogens released into the bloodstream
What is the role of LH during the early follicular phase?
- stimulates the production of androgens in the theca cells
What is the role of FSH during the early follicular phase?
- stimulates the production of aromatase in the granulosa cells
What happens during the mid-follicular phase?
- dominant follicle emerges and continues to produce estrogen
- apoptosis of non-dominant follicles
What happens during the late follicular phase?
- estrogen levels increase dramatically & pos. feedback on release of LH
- peak levels of estrogen stimulates surge of LH
What stimulates ovum release from follicle aka ovulation?
- surge in LH
What happens during the luteal phase?
- empty dominant follicle become corups luteum which secretes progesterone and estrogen
- progesterone & estrogen now inhibit release of FSH/LH
What happens during the luteal phase if fertilization does not occur?
- corpus luteum secreteions progesterone/estrogen/inhibin which inhibit follicle development
- slowly decreases release of progesterone/estrogen/inhibin hormones
- decrease of progesterone/estrogen/inhibin levels constrict bloodflow & leads to menses
What happens during the luteal phase if fertilization does occur?
- corpus luteum will produce/maintain increased progesterone & estrogen levels
What do progesterone and estrogen levels do during pregnancy?
- stay elevated to support pregnancy and inhibit follicular development
What stimulates corpus lutem to produce estrogen/progesterone during pregnancy?
- hCG
What takes over production of estrogen and progesterone during pregnancy?
- placenta
Where is hCG produced and released?
- syncytiotrophoblast
What is the function of hCG?
- human chorionic gonadotropin
- maintains production of estrogens & progesterone in corpus luteum until placenta can take over
- suppresses follicle maturation in maternal ovaries
When is hCG measurable?
- 6-8d after conception
What does the placenta eventually produce?
- progesteron
- estrogen
- CRH
- hPL (human placental lactogens)
What is the function of CRH from the placenta?
- role in regulating birth
- increase or decrease can result in premature or delayed birth
What is the function of hPL from the placenta?
- physical growth
- lactation
When does menopause start?
- 45-55 y/o
What happens during menopause?
- ovarian tissue gradually ceases to respond to FSH & LH
- decreased levels of estrogen and progesterone
