Sex (Lecture 12) Flashcards
sex
biological characteristics that divide organisms into male and female
gender
behavioral characteristics associated with being male or female
gender role
set of behaviors society deems appropriate for people of a given biological sex
gender identity
person’s subjective feeling of being male or female
why has sex evolved?
to reproduce
why sexually reproduce as opposed to on my own (asexually)?
in order to better ft your offspring for a changing environment, different gene provide a greater probability that at lease one gene combination will aid in survival
The Sex Act
Masters and Johnson (1966), identified the 4 stages of sexual response
4 stages of sexual response
- excitement (increased HR, respiration, muscle tone, engorgement of sexual tissue
- plateau (arousal maintained at high level for minutes, preparation for orgasm
- orgasm (rhythmic contractions of genital muscles, intense euphoria)
- resolution (arousal decreases and body regains homeostasis)
male refractory period
unable to become aroused for minutes/hours/days
neural control
may begin in the cerebral cortex (erotic thoughts) but is coordinated (and may begin through stimulation of mechanoreceptors) in spinal cord
info from genitalia or brain activate
parasympathetic NS= engorgement, erection, and lubricating secretions
parasympathetic axons release:
Ach and NO onto erectile tissue (relaxation of smooth muscle= increased blood flow)
increased activity of sensory axons and input from the brain excite:
sympathetic neurons= orgasm (muscle contractions of penis and vaginal walls)
androgens
male hormones, because males have more than females (e.g. testosterone) also produced by adrenals
estrogens and progestins:
female hormones, because females have more than males, (e.g. estradiol, progesterone)
testosterone is important for male ______
male sexual motivation
castration
removal of testes=
- loss of sexual interest and function
- may be maintained IF sexually experienced
- reinstated with T replacement
androgen antagonists
when elected by some criminals:
-80-100% effective in eliminating deviant sexual behavior
hormones important for female ______
female sexual motivation
removal of hormones results in:
(in most species)- females will not copulate unless in “heat”= heightened levels of female sex hormones
(in humans)- will copulate throughout hormonal cycle, but show more initiation of sex during ovulation when estrogen levels are highest
medial pre-optic area of the hypothalamus (mPOA)
involved in male and female sexual behavior
dopamine is important for sexual motivation in:
both sexes and sexual performance in males
DA increases in _____ during sexual stimulation
nucleus accumbens
initially, small amounts of DA during sexual stimulation activate ____ receptors –> activates _______ NS
D1 receptors
parasympathetic
as DA increases, activates ____ receptors –> shifts balance to _____ activation and _____
D2 receptors
sympathetic
orgasm
D2 activation inhibits ____ which accounts for refractory period
erection