1. PHYSIOLOGY OF THE SEXUAL RESPONSE
four phases
Excitation:
Vasocongestion: pelvic area receives more blood in general, in particular to genitals.
Males:
penile erection
scrotal sac thickens, elevates

2. PHYSIOLOGY OF THE SEXUAL RESPONSE
Excitation (Cont’d)
Females:
vaginal lubrication
glans clitoris enlarges (similar to penile erection)
nipples erect (myotonia: muscle contraction)
breasts enlarge (vasocongestion
inner lips of vulva swell and open, change in colour (darker)
upper 2/3rds of vagina balloons
cervix and uterus stand up: tenting effect
angle of cervical opening more receptive to sperm

5. PHYSIOLOGY OF THE SEXUAL RESPONSE
Excitation (Cont’d)
Both Sexes:
sex flush (can happen later)
heart rate, respiration rate gradually increase
generalized myotonia

6. PHYSIOLOGY OF THE SEXUAL RESPONSE
Plateau:
Both males and females continue vasocongestion to max
Heart rate, respiration rate and blood pressure continue to increase
Copious perspiration
Increased myotonia

7. PHYSIOLOGY OF THE SEXUAL RESPONSE
Plateau (Cont’d)
Females:
orgasmic platform: outer third of vagina thickens, swells: condition sine qua non: without it, no orgasm
tenting complete
clitoris erect

8. PHYSIOLOGY OF THE SEXUAL RESPONSE
Plateau (Cont’d)
Males:
Cowper’s glands secrete fluid through tip of penis. WARNING: may contain live sperm!
scrotum even higher and testicles bigger

9. PHYSIOLOGY OF THE SEXUAL RESPONSE
Orgasmic:
Males: Two stages:
contraction of seminal vesicles, vas and prostate
contraction of urethra and penis: ejaculation

10. PHYSIOLOGY OF THE SEXUAL RESPONSE
Orgasmic:
Females:
contractions of orgasmic platform
contractions of uterus
several orgasms possible if stimulation continues
oxytocin

11. PHYSIOLOGY OF THE SEXUAL RESPONSE
Orgasmic:
Both:
very high heart rate, blood pressure and breathing
intense myotonia

12. PHYSIOLOGY OF THE SEXUAL RESPONSE
Health Benefits Associated With Orgasm
General Health
An orgasm at least once or twice per week appears to strength the immune system’s ability to resist flu and other viruses
Pain Relief
Some women find that an orgasm’s release of hormones and muscle contractions help relieve the pain of menstrual cramps and raise pain tolerance in general.

13. PHYSIOLOGY OF THE SEXUAL RESPONSE
Health Benefits Associated With Orgasm (Cont’d)
Lower Cancer Rate
Men who have more than five ejaculations per week during their 20s have a significantly lower rate of prostate cancer later in life
Mood Enhancement
Orgasms increase estrogen and endorphins, which tend to improve mood and ward off depression in women

14. PHYSIOLOGY OF THE SEXUAL RESPONSE
Health Benefits Associated With Orgasm
Greater Feelings of Intimacy
The hormone oxytocin, which may play a role in feelings of love and intimacy, increases fivefold at orgasm
Better Sleep
The neurotransmitter dopamine, released during orgasm, triggers a stress-reducing, sleep-inducing response that may last up to two hours

15. PHYSIOLOGY OF THE SEXUAL RESPONSE
Emotional Changes During Orgasm:
Based on EEG, MRI and PET scans done in the lab while subjects having an orgasm.
General emotional response:
coded in limbic association area, especially prefrontal cortex and cingulate gyrus.
Pleasure:
coded in basal forebrain, especially ventral tegmental area and its dopaminergic stimulation of the reward centres of the septal nuclei and the nucleus accumbens.
Euphoria:
probably by assymetric cortical activation
The proportion and intensity of each varies with each orgasm.
So: orgasms differ

16. PHYSIOLOGY OF THE SEXUAL RESPONSE
Resolution:
Return to normal, muscles relax, breathing etc. back to normal, blood back to circulation from genitals.
Males
refractory period
EACH PHASE MUST BE FULLY COMPLETED IN ORDER TO REACH THE NEXT ONE

18. PHYSIOLOGY OF THE SEXUAL RESPONSE
Each phase shows age changes.
Excitation:
Men:
fastest years, then slow decline
Middle Age:
very noticeable, need direct stimulation
Old Age:
need lots of direct stimulation
Women:
slower in teens, early 20s
faster 30’s on
Plateau:
capacity for longer with age
same, but never a big problem

19. PHYSIOLOGY OF THE SEXUAL RESPONSE
Orgasmic:
Men:
intensity lessens from mid- to late 20s
Middle Age:
really noticeable
ejaculate less volume, less forceful
Resolution:
Refractory period increases

20. PHYSIOLOGY OF THE SEXUAL RESPONSE
Resolution:
Men:
longer refractory periods, 24 hrs. midlife, longer in old age.
Women:
no refractory periods ever.

21.
Females
Intensity of Response
Males
Age

23. NEUROPHYSIOLOGY OF THE SEXUAL RESPONSE
Neural and hormonal involvement in sexual responses:
Parasympathetic:
arousal
Sympathetic:
orgasm
Spinal reflexes:
erection and
ejaculation

24. NEUROPHYSIOLOGY OF THE SEXUAL RESPONSE
Erection:
sacral cord responds to stimulation
sends message via parasympathetic to relax penile arteries:
more blood flows to penis
Also, message to brain
awareness (not if spine severed above sacrum)

25. NEUROPHYSIOLOGY OF THE SEXUAL RESPONSE
Ejaculation:
higher in spinal cord
message to sympathetic that causes muscle contractions
Also, message to brain
Awareness
possibility of control

26. PHYSIOLOGY OF THE SEXUAL RESPONSE
Women’s Neural Mechanisms:
Not yet well known .