Gonadal hormones Flashcards
reproductive hormone produced by hypothalamus & its target
produces Gonadotropin (GNRH) & acts on the pituitary
pituitary response to GnRH
secretes Luteinizing hormone (LH) & Follicle stimulating hormone (FSH) & acts on male testes & female ovaries
FSH on male
FSH acts on germinal stem cells to make sperm
LH on males
LH acts on Leydig cells to form testosterone
FSH on females
FSH acts on follicles to facilitate maturation of ovum
LH on females
LH acts to start luteal phase where ovulation occurs & corpus luteum forms
Feedback
estrogen/testosterone shuts down the release of GnRH & LH & FSH
exception! - female menstrual cycle where estrogen exerts a positive feedback mechanism
Male testosterone
major androgen in males
made in Leydig cells through LH action
transported by sex hormone binding protein (SHBG 45%) & albumin (50%) only 3% is free (most active)
feedback on male testosterone
testosterone & inhibin (!!)
has circadian rhythm- highest concentration at 8 am
Testosterone cellular mechanism
enters cell & converts to dihydrotestosterone (DHT) –> complexes with intracellular receptor –> complex moves to nucleus & nuclear receptors –> binding to DNA leads to protein synthesis & cell growth
enzyme that converts testosterone to DHT
5-alpha reductase
very prevalent in male scrotal skin
testosterone actions before puberty
quiet actions (almost nothing significant)
testosterone actions after puberty
large increases in testosterone
secondary sexual characteristics- facial hair, muscles, voice change, elongation of bones
mood swings
testosterone in male adults
modest testosterone
enough to maintain secondary sexual characteristics
as prostate enlarges, can have hair loss
concern about hypogonadism
hypogonadism in males
hypergonadotropic hypogonadism
hypogonadotropic hypogonadism
Hypergonadotropic hypogonadism lab values in men
increased FSH & LH
decreased testosterone
types of hypergonadotropic hypogonadism in men
Klinefelter syndrome- extra chromosome 47
Testicular Feminization syndrome- androgen resistance
5-alpha reductase deficiency - genotype XY, raised female then at puberty no period & discover male genetics
myotonic dystrophy- autosomal dominate
testicular injury &/or infection - mumps, viral, HIV
Sertoli cell only syndrome- lack germ cells
Hypogonadotropic hypogonadism in men
decrease FSH, LH, & Testosterone
types of hypogonadotropic hypogonadism in men
Kallman’s syndrome- inherited x-liked recessive trait, hypogonadism & no sense of smell
Hyperprolactinemia- increased prolactin
age- decreased testosterone after 30
pituitary disease- acquired hypogonadism, pituitary tumors, surgery etc
replacement therapy in males
complications of polycythemia, prostate cancer risk, sleep apnea, breast formation
need to monitor FSH, LH, testosterone, PSA (prostate specific antigen), CBC, lipid panels & monitor semen indices
female hormones after puberty
FSH & LH lead to secondary hormones of estrogen, progesterone & androgens from ovaries
Estrogens’ general effect
promote breast, uterine, & vaginal development
affects skin, vascular smooth muscles, bone cells & CNS
Progesterone
made by corpus luteum
readies the endometrium for implantation of embryo
cervical mucus thickens & temperature rises
Androgens in females
androstenedione, dehydroandrostenedione, testosterone, DHT
all produced even after menopause
