sex hormones and sexual differentiation Flashcards
hormones
chemical substance secreted by the endocrine glands into the bloodstream
testosterone
- androgen
- secreted by the testes, ovaries and adrenal glands
estrogens
secreted by the ovaries and testes
progesterone
secreted by the ovaries and adrenal glands
- not exclusively female
prolactin
produced in the pituitary
- stimulates production of milk
oxytocin
- stimulates ejection of milk
- produced by cuddling, orgasms, loving feelings
GnRH - gonadotropin releasing hormone
- secreted by the hypothalamus
- stimulates production of FSH and LH in the pituitary
FSH - Follicle stimulating hormone
- controls sperm production and ovum follicle development
- responds to GnRH
LH - luteinizing hormone
- controls testosterone production and ovulation
inhibin
secreted by testes and ovaries to suppress FSH production
- negative feedback loop
- creates monthly cycle of ova, daily sperm production
HPG axis
ovaries :
- FSH from pituitary gland initiates follicular development
- LH causes estrogen secretion -> ovum is released and travels down fallopian tube
testes:
FSH - sperm production
LH - Testosterone production
prenatal sexual differentiation
- 7th week gestation in males, 10th week in females for sexual differentiation
SRY region
-presence of SRY region on Y chromosome is key for sex determining
TDF (testes-determining region)
produced at SRY region
- if proper development occurs, leads to testes development
duct systems
mullerian - female
wolffian - male
prenatal hormones : in absence of TDF and ovaries…
- wolffian ducts degenerate
- mullerian ducts develop into fallopian tubes, uterus, vagina
- tubercle develops into female external genitalia
prenatal hormones : in presence of testes
- secretion of anti-mullerian hormone
- mullerian ducts degenerate
- wolffian ducts develop into epidermis, vas deferens, ejaculatory duct
- tubercle develops into external genitalia
brain differentiation
- male/female brains very similar
- early sex-diff determines estrogen sensitivity of cells in hypothalamus
- presence of T during fetal development desensitizes to estrogen
- crucial to hypothalamic-pituitary-gonad feedback loop
homologous sex organs
glans of penis-glans of clitoris scrotal sac-labia majora testes-ovaries prostate gland-skenes gland cowpers gland-bartholins glands
what makes sex/gender
- chromosomal gender
- gonadal gender
- prenatal hormonal gender
- brain differentiation
- internal organs
- external genital appearance
- pubertal hormonal gender
- assigned gener
- gender identity
if all variables agree, sex is determined
congenital adrenal hyperplasia (CAH)
- genetic female who develops ovaries as fetus
- during prenatal development, adrenal gland produces excess androgens
- external genitals partially male in appearance
- labia partially/totally fused so no vaginal opening
- clitoris enlarged to size of penis
- at birth can be identified as male
- generally have female gender identity
androgen insensitivity syndrome (AIS)
- body cells of genetic males are unable to respond typically to T
- infants genitals appear female with undescended testes
- short vagina with no cervix, no internal reproductive organs
- may produce breasts
intersex and genital reconstruction
- problem of stigma and trauma
- parents distress should not be treated by surgery
- mental health care essential
- honest, complete medical disclosure
- should be assigned a gender without surgery
4 phases of menstruation
- follicular/proliferative
- ovulation
- luteal (14 days before menstruation)
- menstruation/secretory
