Hormones of the Reproductive System – non-pregnancy Flashcards
5 components of the male reproductive system
Testes Epididymis Vas deferens Prostate and seminal vesicles Penis
6 components of the female reproductive system
Ovaries Uterine tubes Uterus Vagina Vulva Breasts
What are the two gonadotrophins
Follicle-stimulating hormone
Luteinising hormone
How is gamete production occur via hormones
Internal an external stimulus causes the hypothalamus to relase kisspeptin, wihch stimulates the release of GnRH
GnRH causes the Ant. P to release LH and FSH
LH acts on endocrine cells to release steroid and peptide hormones, which cause gamete production
FSH stimulates gamete produce directly
(LH can also stimulate gamete production directly in females only)
Explain the negative feedback of hormonal control of gamete production
Steroid and peptide hormones act on adenohypophysis and hypothalamus o reduce the secretion of LH, FSH, GnRH and
kisspeptin
where is the site of sperm production
Tough outer fibrous capsule that encloses the seminiferous tubules of the testes
What lies inbetween the tubules of the testes
Interstitial tissue
What does interstitial tissue contain
testosterone-producing interstitial cells of Leydig
What becomes the vas deferens
Seminiferous tubules leave the testis and join the epididymis, eventually becoming he vas deferens
What is the vas deferens
duct which passes into the abdomen and eventually empties into the urethra
What are Sertoli cells
Located in the seminiferous tubules
Produce and secrete proteins that range from hormones (inhibin and activin) to growth factors, enzymes and ABP
What is the function of inhibin and activin
inhibin - inhibits FSH secretion
Activin - stimulates FSH secretions
What do androgen-binding proteins do
ABP binds to testosterone which becomes less lipophilic and cannot diffuse out of seminiferous tubule lumen
What are Leydig cells
Secrete testosterone
Also convert some testosterone to oestradiol
When are Leydig cells active
Active in the foetus (since testosterone is needed to direct development of male characteristics)
Becomes inactive at birth, then reactivates during puberty
Explain the hormonal control of spermatogenesis
Hypothalamic GnRH promotes release of FSH and LH from adenohypophysis
FSH targets Sertoli cells
This stimulates synthesis of paracrine molecules needed for spermatogenesis
Stimulates ABP and inhibin production
LH targets Leydig cells, which produce testosterone
Sertoli cells mediate testosterone action
What are androgens
Precursors of oestrogen; active during puberty
Explain hormonal regulation of the female RS
GnRH is released from hypothalamus and causes the adenohypophysis to release LH+FSH
LH and FSH act on the ovary to release oestrogen and progesterone
Oestrogen causes the growth of reproductive organs and endometrium
Progesterone causes the maintenance and secretion of endometrium
3 phases of the ovarian cycle
Follicular phase - follicular growth in the ovary
Ovulation - one or more follicles have ripened; ovary releases oocyte
Luteal phase - transformation of ruptured follicle into corpus luteum, which secretes hormones that continue preparations for pregnancy, if pregnancy doesn’t occur than corpus luteum ceases to function
Explain the phases of the uterine cycle
Menses - corresponds to the follicular phase, results in menstrual bleeding form h uterus
Proliferative phase - endometrium adds a new layer of cells in anticipation of pregnancy
Secretory phase hormones from corpus luteum convert the thickened endometrium into a secretory structure ; if pregnancy doesn’t occur then superficial layer of endometrium are lost
Explain what happens in the early follicular phase in relation to hormones
Gonadotrophin (FSH and LH) secretion from AP increases
FSH causes tertiary follicles to begin to mature
As these grow, their cells start to produce steroid hormones
Increasing levels of oestrogens lead to inhibition of FSH and LH secretion, preventing development of additional follicles in the same cycle
Oestrogen stimulates granulosa cells to produce additional oestrogen, follicles can continue oestrogen production even though FSH and LH levels decrease
Explain what happens in mid to late follicular phase regarding hormones
Inhibin and progesterone begin to be secreted
Oestrogen levels remain high leading to enhanced pituitary responsiveness to GnRH
LH secretion spikes, which is essential for final steps of oocyte maturation
Explain what occurs hormonally during early to mid luteal phase
Luteal cells form and secrete hormones
Corpus luteum produces steadily increasing amounts of progesterone, oestrogen and inhibin
Progesterone is dominant hormone
Progesterone and oestrogen exert negative feedback on hypothalamus and AP - secretions of gonadotrophins is stopped
What occurs hormonally in late luteal phase
If pregnancy does not occur, the corpus luteum undergoes apoptosis
As the cells degenerate, progesterone and oestrogen levels decrease
Removing the negative feedback on hypothalamus and AP leading to FSH and LH secretion
