topic 2 - sex differences Flashcards
gene SRY
located on Y-chromosome
turns fetal gonad into testis
- testis-determining factor
- if not there, gonad turns into an ovary
hormones early testis produce
Anti-mullerian hormone (defiminsing)
- anrogens (masculalinising)
in abscence of these hormones - female sex organs develop.
organisational hormone effect
effect remains after the hormone has been removed, often occurs during sensitive period
activational hormone effect
effect is reversible, depending on presence or absence of hormone
nuerons that are responsible for the onset of puberty
GnRH nuerons
how does puberty start
GABA/NPY neurons are shut down, activating the KNDy neurons which then triggers the release of GnRH - 2 hour pattern
what happens when GnRH is released
it is released into the capillaries in the pituitary gland.
When the anterior pituitary gland detects GnRH, it releases FSH and LH.
Post pituitary gland release oxytocin and vasopressin
puberty onset in males
FSH and LH reach teh testis and trigger the release of testosterone.
Testosterone feeds back and binds to receptros in the pituitary gland and hypothalamus which lowers the production of GnRH, FSH and LH - keeping testosterone at a steady level
FSH in males
sperm prodcution
LH in males
testosterone production
FSH and LH in females
FSH - causes follicles to ripen
LH - induce ovulation
the menstrual cycle
When period stops:
Peak of FSH
- ovaries detect this and start follicles growing
- estradial is then produced
- when estradial is high enough it triggers the release of LH and FSH
- LH triggers ovulation
- Corpus lutem releases progesterone and more estradial to line the overian wall incase egg implants
- if no implantation - progesteron and estradial goes down again and cycle starts again
mullerian duct
embryonic structure that develops into female reproductive tract (vagina)
turner syndrome
X-containing gamete fuses with one without sex chromosome: XO (45,X)
- only monosomy that is not lethal in early development
- still 90% lethality
- female internal and external genitalia but ovaries are rudimentary
- short stature (short person, height)
pseudo-autosomal region
PAR1, PAR2
- stretches of DNA that are the same on X and Y
- SHOX is a gene in the pseudo-autosomal region which contributes to height - if haploid, short stature. If three copies you are taller