Unit 3- Reproductive hormones Flashcards
what are three layers of the adrenal cortex?
zona granulosa
zona fasciculata
zona reticularis
what hormone does the zona granulosa produce?
mineralocorticoids (aldosterone)
what hormone does the zona fasciculata produce?
glucocorticoids (cortisol)
what hormone does the zona reticularis produce?
androgens
what are androgens and give the five main ones
male sex hormones:
- testosterone
- dihydrotesterone (DHT)
- androstenedione
- androstenediol
- dehydroepiandrosterone (DHEA/ DHEA-S)
describe the biosynthesis of steroid hormones
cholesterol - pregnenolone - progestagens - androgen (then converted into estrogen)/ cortisol/ aldosterone
what enzyme does zona glomerulosa lack?
17-hydroxylase
what enzyme does zona fasciculata and reticularis lack?
18-hydroxylase
what condition will occur if deficiency in 21-hydroxylase?
sexual ambiguity (unable to produce cortisol/ aldosterone so excess production of androgens)
what role does testerone produced in adrenal glands have in men and women?
small role in men as most from testes - responsible for secondary characteristics
primary source for women - converted into oestrogen -responsible for growth of pubic hair/ sex drive
what happens if there is an overproduction of ACTH in men and women?
no effect in men
masculinisation in women: acne/ hirsitism (facial hair)/ breast shrinkage
what does the first decline in DHEA signify?
adrenarche in boys due to development of zona reticularis - hit puberty
what is the equivalent of adrenarche in girls?
menarche - menstrual cycle
what are the two major functions of the testes? what hormones control these?
spermatogenesis
steroidogenesis
- controlled by FSH/ LH
where does spermatogenesis occur? describe process
seminiferous tubules - spermatagonia produce sperm which enters epididymis for sperm maturation - gain motility and then to vas deferens to combine with prostate fluid to secrete as semen
what role do sertoli cells have and what hormone stimulates them?
surround and faciliate spermatogonia by nourishing germ cells
- produce androgen binding proteins (SHBG) to keep high conc of androgens in testes and carries testosterone to epididymis
- stimulated by FSH
what is the function of the three hormones secreted by sertoli cells?
inhibin - inhibits FSH
activin - stimulates FSH
follistatin - binds & deactivates activin
what role do leydig cells have and what hormone stimulates them?
secrete testosterone
stimulated by LH
what enzyme converts testosterone to DHT?
5 alpha reductase
what enzyme convert testosterone to androstenedione?
17-ketoreductase
what enzyme converts testosterone to estradiol (oestrogen)?
aromatase
what is primary hypogonadism?
serum testosterone and sperm count below normal
FSH/LH above normal
what is secondary hypogonadism?
indicates problem in pituitary gland/hypothalamus
what is the effect of anabolic steroids on men?
partial hypogonadism - feminism - development of breasts but decrease in testicle size - no stimulation of sertoli cells
what condition is an example of congenital primary hypogonadism?
Klinefelter’s syndrome - extra copy of X chromosome - less chest hair/ wide lips/ small testicles
what is the effect of 5-ARD deficiency?
inability to convert testosterone to DHT (which is more physiologically active) - look female at birth but develop small penis in later life
(autosomal recessive)
what is AIS?
androgen insensitivity syndrome - mutation of androgen receptor
genetically male but genitals are female
- body is insensitive to testosterone
what are the two stages of the menstrual cycle?
follicular phase- menstrual phase (0-4)/ proliferative phase (4-14) luteal phase (14-28)
explain hormonal changes and uterine changes that occur in the follicular phase
menstrual phase: decrease in progesterone - breakdown of endometrial lining = bleeding
proliferative phase: increase in oestrogen = endometrial proliferation - follicles develop and secrete more oestrogen/ development of uterine glands
at day 14; surge in oestrogen - causes surge in FSH and LH- LH surge stimulates ovulation
what process occurs in the luteal phase?
formation of corpus luteum - follicles undergo luteinization
- collapse into space behind - formation of blood clot forms core surrounded by collapsed layer of granulosa cells in a thecal cells
- enlarge and develop lipid inclusions
what is the effects of the corpus luteum?
contain large amounts of golgi apparatus, endoplasmic reticulum and mitochondria
- secrete progesterone = build up of stromal cells/ stimulate uterine glands to secrete uterine milk (high in protein and glycogen) to maintain endometrium
- secrete oestrogen - negative feedback to decrease FSH/LH
what will happen if ovum is not fertilised?
corpus luteum degenerated by luteolysis whoch causes decrease in levels of progesterone and oestrogen
- levels of FSH/LH increase in preparation for next menstrual cycle
which hormones will increase if ovum is fertilised?
following implantation of egg, hCG, progesterone and oestrogen levels increase
what is the effect of hCG?
maintains corpus luteum in ovary so that it continues to secrete progesterone - stimulates growth of endometrium eventually form the placenta. once placenta developed levels of hCG decrease after 8 weeks
what are the other effects of progesterone apart from growth of endometrium?
- increases blood flow to uterus
- stimulation of uterine glands
- stimulates production of decidua - supports attachment of placenta
what are the effects of oestrogen during pregnance?
- growth of breasts / lactation
- growth of placenta
- development of fetal organs
what hormone is produced prior to parturition?
relaxin - produced by corpus luteum and placenta
- relaxes joints/ ligaments in pelvis which causes ripening of cervix and dilation of blood vessels
what hormones stimulate contractions?
oestrogen causes contraction - stimulates uterus to produce prostaglandins which decreases level of progesterone and initiate labour
oxytocin - stimulated by pressure of baby on cervix/ pelvic floor - causes powerful contractions
what is the effect of decreased progesterone levels?
braxton hicks - increased myometrial excitability
what is the function of thecal and granulosa cells?
theca - stimulated by LH - converts cholesterol to androgens
granulosa - stimulated by FSH - produces aromatase to convert androgens to oestrogen
