1. Previous lectures and videos: discussed how anatomy & physiology of the human reproductive system are evolutionarily adapted for specific reproductive strategies.
Human sexual responses are also the product of adaptation to maximize reproductive success.
Includes
Emotions
Behaviors
Biochemical changes
Physiological changes
Feelings of pleasure / satisfaction
… (many others)
Clearly, human sexuality and sexual responses are a lot more complex than simply getting a penis into a vagina for the deposition of semen.

2. Humans, like all animals, send and receive many sexual signals indicating availability, willingness, health, stage of arousal, etc. These allow us to communicate before, during, and after sexual intercourse and coordinate our sexual responses. Some are conscious, others are not:
Visual signals:
Changes in eye size, Changes in pupil size, Flushing of face & lips, Changes in posture
Physical signals:
Standing closer, Touching,
Respiratory changes, Sweating
Verbal signals:
Changes in voice volume, Changes in voice pitch, Changes in voice rhythm, Specific sounds
Odors:
Sweat, Pheromones, Vaginal lubrication

3. 1960s: Masters & Johnson defined four “stages of human sexual response” during sexual arousal and intercourse for both men and women :
Excitement
Plateau
Orgasm
Resolution

4. 1960s: Masters & Johnson defined four “stages of human sexual response” during sexual intercourse for both men and women :
Solicitation
Excitement
Plateau
Orgasm
Resolution
Since then, two additional stages have been added before and after these:
Refractory period

5. ? Female Equivalent ? For both physiologic and cultural reasons:
men and women tend to be sexually aroused in different ways
Men tend to be quickly aroused by signals which indicate availability and sexual access. They are not particularly selective, and typically do not view arousal within the context of the relationship with their partner.
Women tend to be aroused more slowly by signals which indicate strength and stability. They are more selective and view arousal more within the context of the relationship.
? Female Equivalent ?

6. For both physiologic and cultural reasons:
men and women tend to be sexually aroused in different ways
Women tend to be aroused more slowly by signals which indicate strength and stability. They are more selective and view arousal more within the context of the relationship.

7. “The male paradigm is simple: erection and release
“The male paradigm is simple: erection and release. Women’s satisfactions and drives are more complex, organized as much around the health of the relationship as the majesty that is orgasm.” Dr. John Bancroft Kinsey Institute
or .....

8. Think about this in the context of human reproductive strategies:
What might be the benefit for reproductive success of the species for
men to be easily aroused by signals which indicate
availability and sexual access and not particularly selective
about their partners, and
women to be aroused more slowly by signals which indicate
strength & stability, more selective, and to view arousal more
within the context of the relationship.

9. As in most (all?) species where the
male produces large numbers of
sperm and the female produces a
small number of eggs, the female has
a “gatekeeper” role: she decides when
and with whom she will mate.
“males compete, and females select
among the competitors”
Thus, it is in the male’s best reproductive interests to always be ready to mate with any female who selects him.
It is in the female’s best reproductive interests to wait for the “best” competitor, and to focus her reproductive energies on that one individual.

10. 1. Soliciting: (Minutes to hours)
Male Sexual Response
1. Soliciting: (Minutes to hours)
Primarily visual and verbal “I am available” “I am healthy” “I am interested in you” “I am sexually aroused”
Eyes and pupils get larger, direct eye contact
“Masculine” posture, stands closer, touches
Lowering of volume, pitch, and rhythm of voice
Conversation to convince woman of masculinity, health, interest, availability, etc.

11. 2. Excitement: (Minutes to hours) Usually during foreplay
Male Sexual Response
2. Excitement: (Minutes to hours) Usually during foreplay
Increased blood flow to skin = flushing Increased respiration and vocalization Increased sweating Secretion of pheromones from armpits, genitals, anal region Erection of penis Elevation of testes Increased secretion of fluids by seminal vesicles and prostate Pituitary increases oxytocin secretion, causing feelings of pleasure and “drive”

12. 3. Plateau: (Minutes) Intercourse begins
Male Sexual Response
3. Plateau: (Minutes) Intercourse begins
Sweating and flushing continue,
Increased respiration, vocalization continue Heart rate and blood pressure rise Swelling of glans of penis Full elevation of testes Lubrication of urethra by bulbourethral (Cowper’s) glands Leakage of sperm and fluid from seminal vesicles & prostate into ejaculatory duct Secretion of oxytocin from pituitary increases, thus increased pleasure and “drive”

13. Male Sexual Response 4. Orgasm: (Seconds)
Heart rate, blood pressure, respiration very high Contraction of sphincter (valves) between bladder
and urethra prevents urination Contraction of sphincter in anus prevents defecation Ejaculation occurs in two phases: Emission: Contraction of ductus deferens, seminal vesicles, and prostate force semen into urethra Expulsion: Contraction of muscles surrounding urethra eject semen from urethra Secretion of oxytocin from pituitary very high
Brain produces many other “pleasure”
chemicals; thus strong feelings of pleasure and satisfaction.

14. 5 Resolution: (Minutes)
Male Sexual Response
5 Resolution: (Minutes)
Heart rate, blood pressure, respiration return to normal Sweating and flushing decrease
but may not completely disappear Testes descend to normal position in scrotum Penis softens, eventually becomes flacid Sphincters of bladder and anus relax Oxytocin secretion from pituitary decreases slowly (minutes/hours)

15. 6. Refractory Period: (Minutes to hours)
Male Sexual Response
6. Refractory Period: (Minutes to hours)
General body relaxation, drowsiness Lower parts of ductus deferens
move sperm toward ampulla Seminal vesicles and prostate begin
replacing fluids Erection or ejaculation not possible
Can also enter refractory period from excitement
or plateau periods if orgasm does not occur
If proper stimuli still present, men typically
re-enter excitement phase after refractory period

16. Female Sexual Response
1. Soliciting: (Minutes to hours)
Primarily visual and verbal, includes physical signals and odors “I am available” “I am healthy” “I am interested in you” “I am sexually aroused”
Eyes and pupils get larger, direct eye contact
“Feminine” posture, exposes more of body, stands closer, touches
Lowering of volume, pitch, and rhythm of voice
Conversation to convince man of femininity, health, interest, availability, etc.
Odors from pheromones and vaginal lubrication

17. Time Magazine However:
“Studies have shown that men more often view flirting as indicative of sexual interest, while women see it simply as fun and friendly behavior”
Time Magazine

18. Female Sexual Response
2. Excitement: (Minutes to hours) Usually during foreplay
Increased blood flow to skin = flushing Increased respiration and vocalization Increased sweating Secretion of pheromones from armpits, genitals, anal region Erection of clitoris and nipples Swelling of vagina and of labia Elevation of uterus begins Lubrication of vagina begins (mostly distal part) Pituitary increases oxytocin secretion, causing feelings of pleasure and “drive

19. Female Sexual Response
3. Plateau: (Minutes to hours) Intercourse begins
Sweating, flushing, increased respiration, vocalization continue Heart rate and blood pressure rise Swelling of vagina and of labia continue Erection of clitoris more pronounced Elevation of uterus continues, swelling of uterus Lubrication of vagina and vestibule by vestibular (Bartholin’s) glands Pituitary increases oxytocin secretion, causing feelings of pleasure and “drive”

20. Female Sexual Response
4. Orgasm: (Seconds to a minute or two)
Heart rate, blood pressure, respiration very high Contraction of sphincters (valves) between
bladder and urethra prevents urination Contraction of sphincter in anus prevents defecation Rhythmic contractions of vagina Rhythmic contractions of uterus, primarily cervix Contractions of muscles surrounding vagina to “grasp” penis Secretion of oxytocin by pituitary very high (more than in men) while brain produces many other “pleasure” chemicals; thus strong feelings of pleasure and satisfaction.

21. Female Sexual Response
5. Resolution: (Minutes)
Heart rate, blood pressure, respiration return to normal Sweating and flushing decrease but may not completely disappear Uterus returns to normal position Swelling of uterus, vagina, and labia decreases Clitoris softens Sphincters of bladder and anus relax Muscles surrounding vaginal opening relax Oxytocin secretion from pituitary gland decreases more slowly than in men
(minutes/hours), thus period of pleasure/
satisfaction lasts much longer

22. Female Sexual Response
Refractory period generally does not occur in women
If proper stimuli still present, woman
may re-enter at excitement, plateau,
or orgasm phases.
Thus, multiple orgasms possible