Chapter 8: sexual arousal Flashcards
Vasocongestion (during excitement)
Blood-flow to the vessels in the genital region as a result of dilation of these vessels. Blood is send to the corpora cavernosa and the corpus spongiosum (erectile tissue in the penis).
Myotonia (during arousal)
The contraction of muscles (not only in the genitals, but also in the rest of the body).
Vasoconstriction (after arousal)
Makes the erection go away.
Orgasm in men
- Preliminary stage: the vas, seminal vesicles and prostate contract, forcing the ejaculate into a bulb at the base of the urethra.
- Second stage: the urethral bulb and the penis contract rhythmically, forcing semen out of the penis.
Urethra
The tube through which the urine and ejaculate leave the body (in men).
Sexual response cycles
- Excitement
(Platform) - Orgasm
- Resolution
Excitement in women
- Vasodilation and vasocongestion: the cappilaries (veins) in the vagina dilate causing more bloodflow.
- Fluid flows through the semipermeable membranes of the vaginal walls, causing lubrication.
- Erection of the clitoris (the glans of the clitoris swells), due to engorgement (stuwing) of the corpora cavernosa.
- Erection of the nipples, by myotonia (contractions) surrounding the nipple.
- The inner lips are folded over and well open.
- Heart rate, breathing rate and blood pressure increase.
- Muscles in the whole body contract.
Excitement in men
- Vasodilation: the vessels dilate.
- Vasocongestion: blood flows into the corpora.
- Veins carrying blood away are compressed.
- Pulse rate, breathing rate and blood pressure increases.
- The skin of the scrotum thickens.
- Muscles in the whole body contract.
Corpora
The erectile tissue in the penis. Consists of the corpus cavernosa and the corpus spongiosum.
Orgasms in women
- The orgasmic platform forms: tightening of the entrance of the vagina, because of contracting muscles.
- The muscles around the anus and the uterus contract rhythmically.
(A small orgasm contains 3 or 4 contractions, and a large one can contain up to 12 contractions).
Masters and Johnsons
Said that there are NO differences between clitoral and vaginal orgasms (like Freud said) and the likeliness of an orgasm depends on the clitoral-urethral meatus distance. Women can have multiple orgasms, because they have no refractory period.
Neurotransmitters regulating excitement
Nitric oxide, dopamine, (nor)epinephrine, estrogen (in women)
Resolution stage (in women)
- 5-10 seconds after an orgasm, the clitoris moves back (moves up during sex).
- After 15-30 minuten is shrinks back to it’s normal size (takes longer when there was no orgasm).
Resolution stage (in men)
- Detumescence: the penis loses its erection. This first happens fast due to emptying of the corpus cavernosa and then slow due to emptying of the corpus spongiosum and the glans.
- Refractory period: during which a man can not be aroused again.
Kaphlan’s Triphasic model (of the sexual response)
There are 3 independent stages of sexual response:
1. Sexual desire
2. Vasocongestion
3. Reflexive muscular contractions (orgasm)
This theory is based on the following principles:
- Arousal is controlled by the parasymphathic system and orgasm by the symphathic system.
- Arousal and orgasm involve different anatomical structures (blood vessels and muscles).
- Arousal and orgasm vary in their susceptibility to be disturbed.
- Ejaculation can be controlled, but erection can not.
- Impairment of the 2 systems produces different sexual disorders.
Dual control model (Bancroft)
The sexual response is regulated by sexual inhibition and sexual excitation.
Erection reflex
- Is produced by the spinal reflex.
- 1 erection center in the spinal cord.
- Caused by the parasympathetic system –> smooth muscles relax.
- Vasocongestion.
Ejaculation reflex
- There are 2 ejaculation centres in the spinal cord.
- Both the parasympathetic and the sympathetic systems are involved in ejaculation.
- The response is muscular with NO vasocongestion.
Orgasm reflex
- Sensory input travels through the dorsal nerve, through the pudendal nerve.
- Goes to a reflex centre in the spinal cord.
- Parasymphatic system.
What are the stages of sexual response?
- Anticipatory phase: sexual interest, desire, arousal.
- Consummatory phase: sexual activity and orgasm.
- Post-orgasmic: resolution phase and refractory period.
Neurotransmitters that regulate excitement and arousal
Dopamine, melanocortin, oxytocin and norepinephrine.
Inhibitory processes in the brain (after an orgasm)
Opioids are released in the cortex, the limbic system and the hypothalamus in response to an orgasm. Opioids relax the body and can relieve pain.
Testosterone
Has effect on libido. A decrease of testosterone can lead to less sexual desire and high levels of testosterone leads to higher sexual activity. Testosterone is made in the testes.
Physical castration
Removal of the testes. Cuts of they testosterone production, which can lead to less sexual desire (but this can stay for a couple of years, because desire is also controlled by the brain).
Chemical castration
Injection of an anti-androgen drug that reduces the levels of testosterone. Takes sexual desire completely away in animals, but in humans this is not only hormone-driven.
Menstrual synchrony
Women’s cycles can synchronise because of pheromones. Smelling another woman’s vaginal secretion who is near to ovulation can trigger the LH surge which can cause an early ovulation.
Anilingus
The tongue and the mouth stimulate the anus.
Aphrodisiacs
A substance that excites sexual desire, like marihuana, alchohol and poppers.
Anaphrodosiacs
A substance that decreases sexual desire, like cold showers, potassium nitrate and cyproterone acetate.
