Chapter 8: sexual arousal

Question 1

Vasocongestion (during excitement)

Answer 1

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).

Question 2

Myotonia (during arousal)

Answer 2

The contraction of muscles (not only in the genitals, but also in the rest of the body).

Question 3

Vasoconstriction (after arousal)

Answer 3

Makes the erection go away.

Question 4

Orgasm in men

Answer 4

1. Preliminary stage: the vas, seminal vesicles and prostate contract, forcing the ejaculate into a bulb at the base of the urethra.
2. Second stage: the urethral bulb and the penis contract rhythmically, forcing semen out of the penis.

Question 5

Urethra

Answer 5

The tube through which the urine and ejaculate leave the body (in men).

Question 6

Sexual response cycles

Answer 6

1. Excitement
   (Platform)
2. Orgasm
3. Resolution

Question 7

Excitement in women

Answer 7

1. Vasodilation and vasocongestion: the cappilaries (veins) in the vagina dilate causing more bloodflow.
2. Fluid flows through the semipermeable membranes of the vaginal walls, causing lubrication.
3. Erection of the clitoris (the glans of the clitoris swells), due to engorgement (stuwing) of the corpora cavernosa.
4. Erection of the nipples, by myotonia (contractions) surrounding the nipple.
5. The inner lips are folded over and well open.
6. Heart rate, breathing rate and blood pressure increase.
7. Muscles in the whole body contract.

Question 8

Excitement in men

Answer 8

1. Vasodilation: the vessels dilate.
2. Vasocongestion: blood flows into the corpora.
3. Veins carrying blood away are compressed.
4. Pulse rate, breathing rate and blood pressure increases.
5. The skin of the scrotum thickens.
6. Muscles in the whole body contract.

Question 9

Corpora

Answer 9

The erectile tissue in the penis. Consists of the corpus cavernosa and the corpus spongiosum.

Question 10

Orgasms in women

Answer 10

1. The orgasmic platform forms: tightening of the entrance of the vagina, because of contracting muscles.
2. 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).

Question 11

Masters and Johnsons

Answer 11

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.

Question 12

Neurotransmitters regulating excitement

Answer 12

Nitric oxide, dopamine, (nor)epinephrine, estrogen (in women)

Question 13

Resolution stage (in women)

Answer 13

1. 5-10 seconds after an orgasm, the clitoris moves back (moves up during sex).
2. After 15-30 minuten is shrinks back to it’s normal size (takes longer when there was no orgasm).

Question 14

Resolution stage (in men)

Answer 14

1. 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.
2. Refractory period: during which a man can not be aroused again.

Question 15

Kaphlan’s Triphasic model (of the sexual response)

Answer 15

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.

Question 16

Dual control model (Bancroft)

Answer 16

The sexual response is regulated by sexual inhibition and sexual excitation.

Question 17

Erection reflex

Answer 17

• Is produced by the spinal reflex.
• 1 erection center in the spinal cord.
• Caused by the parasympathetic system –> smooth muscles relax.
• Vasocongestion.

Question 18

Ejaculation reflex

Answer 18

• 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.

Question 19

Orgasm reflex

Answer 19

• Sensory input travels through the dorsal nerve, through the pudendal nerve.
• Goes to a reflex centre in the spinal cord.
• Parasymphatic system.

Question 20

What are the stages of sexual response?

Answer 20

1. Anticipatory phase: sexual interest, desire, arousal.
2. Consummatory phase: sexual activity and orgasm.
3. Post-orgasmic: resolution phase and refractory period.

Question 21

Neurotransmitters that regulate excitement and arousal

Answer 21

Dopamine, melanocortin, oxytocin and norepinephrine.

Question 22

Inhibitory processes in the brain (after an orgasm)

Answer 22

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.

Question 23

Testosterone

Answer 23

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.

Question 24

Physical castration

Answer 24

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).

Question 25

Chemical castration

Answer 25

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.

Question 26

Menstrual synchrony

Answer 26

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.

Question 27

Anilingus

Answer 27

The tongue and the mouth stimulate the anus.

Question 28

Aphrodisiacs

Answer 28

A substance that excites sexual desire, like marihuana, alchohol and poppers.

Question 29

Anaphrodosiacs

Answer 29

A substance that decreases sexual desire, like cold showers, potassium nitrate and cyproterone acetate.