Control of sexual behaviour Flashcards
What are the two types of sexual behavior?
Appetitive behavior – Behavior aimed at finding a sexual partner.
Consummatory behavior – Behavior of the actual sex act.
What are the two main factors influencing sexual motivation?
External stimuli (e.g., opposite-sex conspecifics, pheromones, learned sensory cues).
Internal motivation (e.g., hormones, brain mechanisms).
What is the function of pheromones?
They are species-typical molecules that trigger a specific response in another animal of the same species.
What evidence suggests that humans produce pheromones?
Women’s T-shirts smell sexier during the fertile phase of the menstrual cycle.
Androstadienone (in men’s sweat) improves mood and sexual arousal in women but lowers men’s mood.
Estratetraene activates the male hypothalamus but not the female hypothalamus.
How do sex hormones influence sexual interest in males?
Suppression of testosterone (T) reduces sexual interest (but not performance).
Anticipation of sexual activity increases testosterone levels.
No correlation between individual testosterone differences and sexual interest.
How do sex hormones influence sexual interest in females?
Sexual motivation fluctuates across the menstrual cycle.
Sexual interest increases with oestradiol.
Androgens (testosterone, androstenedione) amplify oestradiol’s effects up to 3 times.
Testosterone also increases with anticipation of sexual activity.
What are the four stages of arousal?
Excitement
Plateau
Orgasm
Resolution
What is the role of the parasympathetic nervous system in sexual arousal?
Relaxes smooth muscle in blood vessels.
Increases blood flow to genitals.
Causes penile/clitoral erection, engorgement of labia, and vaginal lubrication.
What is the biochemical mechanism of erection?
Nitric oxide (NO) signals smooth muscle relaxation.
cGMP increases, keeping smooth muscle relaxed.
Viagra inhibits phosphodiesterase 5, preventing cGMP breakdown.
What are the causes of erectile dysfunction?
Increased sympathetic activity (stress) leads to vasoconstriction.
Learned aversions can have central effects.
What nervous system is responsible for orgasm?
The sympathetic nervous system
What happens during orgasm?
Triggered by local stimulation + central input.
Sympathetic stimulation + oxytocin release → pelvic floor contractions.
Disinhibition by CNS required.
What brain regions are involved in central inhibition of orgasm?
Medulla inhibits orgasm circuitry in lumbar spinal cord.
Hypothalamus inhibits the peri-aqueductal gray, which normally stimulates the medulla.
What happens during the resolution phase?
Sexual motivation is actively inhibited.
Oxytocin peaks (pair bonding).
Prolactin is released (suppresses motivation).
What are the key conclusions about sexual motivation?
Sex steroids play a crucial role in motivation.
The sexual response is a reflex arc, modulated by the central nervous system.
