sex and the brain

which region on the Y chromosome determines the sex and what does it code for

sex-determining region (SRY) codes for testis-determining factor (TDF)

de la chapelle syndrome

two X chromosomes but develops as male, SRY jumps to the X chromosome during recombination

swyer syndrome

XY chromosomes but develops as female, SRY is mutated or non-functional

turner syndrome

only X chromosome, develops as female with non-functional genitalia

klinefelter syndrome

XXY chromosomes, develops as male but presents certain female characteristics

TDF effect on sexual organ differentiation

mullerian duct degenerates and wolffian duct becomes vas deverens

effect of lack of TDF on sexual organ development

mullerian duct becomes oviduct and wolffian duct degenerates

androgens

male sex hormones, testosterone, digydrotestosterone, androstenedione

estrogens

female sex hormones, estradiol, estrone, estriol

what is the precursor of all sex hormones

cholesterol

which areas of the brain have the highest density of sex hormone receptors

pituitary, hypothalamus, preoptic area

how are gonadotropins released

eye signals the hypothalamus to release GnRH, which acts directly on the pituitary to release gonadotropins

gonadotropins

important for sexual development and signaling gonads to release sex hormones, LH, FSH

what is sexual behavior mediated by

spinal cord, parasympathetic pathway

which NS is orgasm controlled by

sympathetic NS

evolutionary advantage of monogamy for humans

reproduction is costly, pregnancy last 9 months, 2 parents make it easier for offspring to survive

vasopressin

expressed more by males, active with monogamous animals

oxytocin

expressed more by females, active with monogamous animals

why do animals orgasm

sex feels good so we do more of it to survive, male orgasm releases sperm, female orgasm contracts the uterus to pull sperm up

why is testosterone reduced in males when they become fathers

to reduce promiscuity and invest more resources into raising offspring

sexual dimorphism

sex has a direct effect on the morphism of the brain and body

sexually dimorphic nucleus (SDN)

in the preoptic area, larger in heterosexual males

effect of lesions to SDN

disruptions in menstrual cycle (female), reduced sex drive (male)

direct effect of estradiol on the brain

influence post-synaptic potentials

indirect effect of estradiol on the brain

influence gene expression

gynadromorphism

organism is half-male, half-female, mediated both by genes and hormones