Sexual Behaviors Flashcards
müllerian ducts
precursors to female internal structures (present in males and females in early prenatal development)
wolffian ducts
precursors to male internal structures (present in both males and females in early prenatal development)
sex-determining region on Y chromosome (SRY gene)
sex-determining region on the Y chromosome. causes undifferentiated gonads to develop into testes which then produce testosterone and MIG to direct development towards the male pattern
androgens
hormones more abundant in males that increase the growth of the testes (positive feedback). also cause solffian ductso to develop into seminal vesicles & vas deferens.
müllerian inhibiting hormone (MIH)
released by testes to cause müllerian ducts to degenerate.
development of penis & scrotum
SRY gene -> causes gonads to -> testes -> release androgens -> (cause growth of testes -> release of androgens) -> androgens cause wolffian ducts to become -> seminal ducts & vas deferens -> testes produce müllerian inhigibing hormone (MIH) -> causes müllerian ducts to degenerate
development of ovaries
lack of SRY gene -> development of gonads -> ovaries -> wolffian ducts degenerate -> müllerian ducts develop into -> oviducts, uterus & upper vagina
estrogens
hormones more abundant in females. produced by ovaries
steroid hormones
hormones that contain four carbon rings and derived from cholesterol.
3 ways steroids exert effects
1) bind to membrane receptors to exert rapid effects.
2) they enter cells & activate certain kinds of proteins in the cytoplasm
3) bind to receptors that bind to chromosomes where they activate/inactivate certain genes
most widely known androgen
testosterone
2 most widely known estrogen
estradiol & progesterone
progesterone
prepares the uterus for implantation of fertilized ovum & promotes maintenance of pregnancy
organizing effects
long lasting structural effects occur during sensitive stage of early development before birth which determines whether body will be male or female
activating effect
temporary effects present when a hormone increases some activity that lasts only when that hormone is present. can occur at any time in life.
sensitive period
when hormones determine whether an embryo develops male or female anatomy (3- mo of pregnancy)
high levels of estrogens and androgens during early development would cause what genital appearance?
the animal would appear male.
low levels of estrogens and androgens during early development would cause what genital appearance?
the animal would appear female.
what are some drugs pregnant women should avoid to protect a male fetus’s sexual development?
alcohol, aspirin, haloperidol, cocaine…
sexually dimorphic nucleus
larger in males & contributes to control of male sexual behavior. found in anterior hypothalamus
what does the female hypothalamus do that males cannot?
generate cyclic pattern of hormone release (i.e. menstrual cycle)
alpha-fetoprotein
not present in adults. binds with estradiol & prevents it from entering cells where it could masculinize. present in females not males.
how would the external genitals appear on a genetic female rat that lacked alpha-fetoprotein?
they would be masculinized by her own estradiol
multiplier effect
tendency to provide more of the preferred toys to children, thus strengthening their preference for those toys
what evidence most directly links children’s toy play to prenatal hormones?
higher testosterone in utero caused girls to have more boy-type play. higher phthalates in utero caused boys to have less interest in boys’ toys.
how quickly can changes in hormonal secretions influence sexual behavior?
15 minutes
sex hormones activate sexual behavior partly by enhancing…?
sensations. the sensitivity to tactile stimulation from the vagina and cervix, and the penis is increased.
erection
testosterone increases release of nitric oxide (NO), which increases blood flow to the penis.
how does viagra (sildenafil) work?
prolongs the effects of nitric oxide
how do testosterone & estradiol affect the hypothalamic areas responsible for sexual behavior?
they prime hypothalamic cells to be ready to release dopamine. they also increase sensitivity in the genital area.
impotence
the inability to have an erection
what is the explanatio for why married men tend to have lower testosterone levels than single men of the same age?
men w/lower testosterone levels are more likely to get married than men with higher levels
menstrual cycle
periodic variation in hormones/fertility over about 28 days. produced by hypothalamus & pituitary
follicle-stimulating hormone (FSH)
released by anterior pituitary which promotes the growth of a follicle in the ovary.nurtures the ovum and produces several types of estrogen.
lutenizing hormone (LH)
released by anterior pituitary toward middle of menstrual cycle. combined with FSH, causes the follicle to release an ovum
birth control pills
prevent pregnancy by interfering with the feedback cycle between the ovaries and the pituitary.
periovulatory period
days around the middle of the cycle is the time of maximum fertility & high estrogen levels.
at what time in a woman’s menstrual cycle do her estradiol levels increase? when are they lowest?
estrogen levels increase during days leading up to the middle of the menstrual cycle. they are lowest during and just after menstruation.
oxytocin
stimulates contractions of the uterus during delivery and stimulates mammary gland to release milk. prevents anxiety after orgasm. facilitates formation of bonds between mates, and between mother/infant. increases trust toward someone you already love, but not everyone.
vasopressin
important for social behavior by facilitating olfactory recognition of other individuals
what factors are responsible for maternal behavior shortly after rats give birth? what factors become more important in later days?
early stages of maternal behavior depends on a surge in the release of prolactin and estradiol. after exposure to the babies’ smell, hormone level drops, but learned behaviors remain.
sexual selection
genes that make an individual more appealing to the other sex will increase the probability of reproduction & the next generation will resemble those who had these favorable genes
major histocompatibility complex
women’s avoidance of a man of similar odor
gender identity
how we identify sexually and call ourselves
sex differences
biological differences between males and females
gender differences
differences from people’s thinking about themselves as male or female. strictly a human characteristic.
hermaphrodite
individuals who appear to be a mixture of male and female.
congenital adrenal hyperplasia (CAH)
common cause of XX female to develop masculinized genitals. overdevelopment of adrenal glands from birth. (genetic limitation to produce cortisol, causes failure of pituitary since it doesn’t receive cortisol as a feedback signal and it continues to secrete other hormones, including testosterone). in females, this causes masculinization of their genitals
intersexes
people whose sexual development is intermediate. 1 in 100 in US has some uncertainty; 1 in 2000 is ambiguous enough to be uncertain of male or female
androgen insensitivity / testicular feminization
individuals with XY chromosome pattern who have the genital appearance of a female (producing androgen, but lack the receptors)
