Lecture 7 Flashcards
Coitus:
: a specific type of Sexual Intercourse – IT!
In humans, coitus is a specific act of male-female genital sex in which the erect penis of the male is inserted into the vagina of the female. One or both of the partners moves to create friction on the penis, resulting in stimulation to a level of arousal resulting in orgasm.
Humans are capable of many sexual activities (including sexual intercourse) involving opposite-sex or same sex partners, many of which do not culminate in coitus (male-female sexual intercourse). Different phases of the sexual response may be involved with any of these, but here we are focusing on coitus.
Masters and Johnson (1966) – Four-Phase Model of Human Sexual Arousal (4 phases)
Phase 1: Excitement – increased muscle tension, heart rate, blood pressure, tissue engorgement (range of minutes to hours)
Phase 2: Plateau – increased sexual tension, enhancement of phase 1 symptoms, increased coloration of genitals (range of seconds to several minutes)
Phase 3: Orgasm – peak of excitement resulting in smooth and skeletal muscle response (lasts seconds)
Phase 4: Resolution – sexual systems return to non-excited state, if no further stimulation begins immediately following orgasm
GRAPH
Kaplan’s (1974) Three-Phase Model of Sexual Arousal(3 STAGES)
Three stages: Desire Excitement Orgasm Note: not all sexual expression is preceded by desire
Two fundamental physiological responses recognized:
Vasocongestion = engorgement with blood of body tissues responding to sexual stimulation (e.g. penis in males, vagina and labia in females)
Myotonia = increased muscle tension
Kaplan’s Three-Phase Model of Sexual Arousal
Desire Phase: Psychological compnents of sexual desire
Vasocongestive Phase: Vasocongestion in pelvic region & increased myotonia
Orgasmic Release Phase: Reversal of Vasocongestion & Releaseof myotonia
GRAPH
Masters and Johnson Sexual Response Cycle for Males
Excitement proceeds to a plateau level where it is maintained until reaching a climactic orgasm followed by resolution.
Resolution includes a refractory period during which no orgasm is possible.
Refractory periods vary by individual, age, physical condition, etc. – they run from several minutes to several hours
GRAPH
Male Sexual Circuitry
Sympathetic nervous system is responsible for fight or flight condition – inhibits erection (not an easy thing with which to fight or fly).
Parasympathetic nervous system is the relaxing system – it reverses the effects of the sympathetic system and allows erection. Hence, it is excitatory.
The penis would be in a constant state of arousal if the sympathetic system did not override the parasympathetic.
Conversely, the sympathetic system must be overridden by excitatory stimuli that move the individual out of the inhibited state.
PICTURE
Male Orgasm
Spinal cord emits nerve impulses that initiate the start of ejaculation.
Smooth muscle contractions of vas deferens propel sperm and fluid from the epididymus. Fluids from prostate, and seminal vesicles join and enter urethra as semen.
Expansion of urethra causes pudendal nerve to signal contractions of urethral muscles to expel semen.
Groin and penis muscles contract.
Voluntary muscle control is lost and some muscles spasm.
Masters and Johnson Sexual Response Cycle for Females
Three variations on the four phase model.
Individuals may respond in any of the three variations or combinations thereof.
A. Excitement phase progresses rapidly followed by multiple orgasms (no refractory period)
B. High level of excitement (enhancement) phase is maintained with no orgasm.
C. Rapid rise in excitement with no plateau, quick orgasm with rapid descent to resolution.
GRAPH
Vaginal Contraction?
Muscles responsible for vaginal contraction and orgasmic spasms.
Female breast responses during sexual arousal
Female Orgasm
Uterine muscles contract in rhythmic waves.
Groin and vaginal muscles contract.
Voluntary muscle control is lost and some muscles spasm.
