Hormones and Sex

Question 1

Causes of differences

Answer 1

Masculinising of brain is caused by estradiol
Aromatisation of testosterone produces estradiol
Blocking aromatisation blocks masculisation
Human females protected from mothers estradiol by placenta

Question 2

Hormonal disorders

Answer 2

Turner’s syndrome results from abnormal sex chromosomes XO chromosome - neither ovaries or testes develop
Persistent Müllerian duct syndrome has two causes: either a failure to produce anti-Müllerian hormone or the absence of receptors for this hormone

Question 3

Behavioural changes: maternal stress reduces dimorphism

Answer 3

Male rat born to stressed mothers, less likely to display male sexual behaviour (Ward, 1972)
Medial preoptic area of the brain larger in males than females, is reduced by maternal stress

Question 4

Pre-natal hormonal control of aggression in females

Answer 4

Being next to a male fetus increases female blood levels of testosterone Vom Saal and Bronson (1980)

Question 5

Hormonal control of sexual behaviour

Answer 5

Males
Reduction in testosterone levels leads to reduction in sexual behaviour (Money and Ehrhardt, 1972)
Thinking about sex increases levels of testosterone (Hellhammer, Hubert and Schurmeyer, 1985)
And it makes you grow a beard faster
Some effects of testosterone caused by aromatised testosterone-estradiol (Warne and Zajac, 1998)
Castration may cause only slow decline in sexual activity maybe related to previous levels of activity (Grunt and Young 1952)
Androgens produced by adrenal gland, prostate gland and fat tissue (Carter, 1992)
Oxytocin responsible for refractory period and “afterglow” (Foster et al, 1990)
Oxytocin increases memory for faces but not nonsocial stimuli in both men and women (Rimmele et al, 2009)

Question 6

Neural control of sexual behaviour in males

Answer 6

See pic

Question 7

Hormonal control of sexual behaviour

Answer 7

Females
Fluctuations in ovarian hormones showed little correlation with sexual activity (Morries et al, 1987)
Study of lesbian couples found significant increase in activity during synchronised ovulation (Matteo and arises an, 1984)
Studies on hormone replacement in women following hysterectomy found injection of testosterone not estradiol increased sexual motivation (Sherwin, 1985)
Testosterone released from adrenal gland highest just prior to ovulation

Question 8

Gender differences in brain

Answer 8

Men’s brains 15% larger than women’s brains
Women’s hemispheres share more functions than men
Different size in medial preoptic area of hypothalamus