sex differences Flashcards
What are organisational effects
- effects on tissue differentiation and development
* permanent
what are activantional effects
- effects that occur in fully developed organism; may depend on prior exposure to organisational effects of hormones
- transient
what are the types of hormone action
organisational and activational effects
What is sexual dimorphisms
(differences in anatomy, physiology and behaviour between males and females)
what does Sexual differentiation in mammals depend on
organisational effects of hormones during development
where is DNA present
DNA is present in the nucleus of every cell (except red blood cells)
How many pairs of autosomes do humans have
22
what is an autosome
doesnt determmine sex differneces
Gametes are haploid… meaning…
just one copy of each chromosome
Gametes fuse to create
diploid offspring
What is gonadal
Undifferentiated ‘primordial’ gonads (yet to develop sex characteristics)
what does SRY stand for
sex-determining region Y gene
What happens to the ovary in early embryonic development
- ovary does not produce significant amounts of steroid hormones during embryonic development
- each part of the body develops according to its own intrinsic programme
what hormone is produced in the testes that leads to mascullinises internal genitalia
Anti-mullerian hormone (AMH)
what is testosterone
• steroid hormone fat-soluble, passes readily through cell membrane • primary androgen • synthesised by Leydig cells in testes • Sertoli cells produce AMH
what does 5-alpha-reductase do
Testosterone is converted DHT. This is catalysed by enzyme 5-alpha-reductase. Females also have this enzyme but no testosterone to convert to DHT. DHT is a more potent form of testosterone.
what does genotypic sex determine
gonadal sex
what does gonadal sex determine
phenotypic sex
what does AMH leadto
internal genitalia
what does DHT lead to
external genitalia
what does testosterone lead to
rest of body
what does Further organisational effects of hormones at puberty lead to
- anterior pituitary releases growth hormone, gonadotropic hormone and adrenocorticotropic hormone (stimulates adrenal cortex)
- leads to development of secondary sexual characteristics (not present at birth)
What do homicide rates show
- men kill men much more frequently than women kill women
- most victims and offenders are young men
- this pattern is stable across cultures and over time
What was found with female guinea pigs wth testosterone
Female guinea pigs treated with testosterone when pregnant produce defeminised, masculinised daughters with male-typical behaviour
what was found aboit Female rhesus macaques given testosterone as newborns
Female rhesus macaques given testosterone as newborns show male-typical behaviour as adults: • pursuit and mounting of other females • pelvic thrusting • post-ejaculatory behaviours • preference for female partners
how mcuh larger are the Song control region in zebra finches in males than femalesz
5-6 times
example of sexually dimorphic brain
Song control region in zebra finches
• 5–6 times larger in males than in females
• gets bigger in females given testosterone as hatchlings
Rat hypothalamus: sexually dimorphic nucleus of pre-optic area (SDN-POA)
• smaller in males castrated at birth
• bigger in females given testosterone at birth
• no effect of castration/testosterone treatment in adulthood
how much heavier are male brains than female
On average male brains are 120–160 g (10–15%) heavier
Also heavier relative to body size
Difference present at birth despite equal body weights
which sex is less strongly lateralised
female
Parts of corpus callosum are bigger in right-handed than left-handed men; no such pattern for women
true or false
true
