Lecture Notes, Biology 203, Human Sexuality and Reproduction

Human Sexual Response

  1. Masters and Johnson's research
    1. First researchers to study physiology of sexual response
    2. Had to devise special equipment, find volunteers
    3. Results summarized in book published 1964, Human Sexual Response, very dry reading
    4. Phases: excitement, plateau, orgasmic, resolution
    5. Physiological changes
      1. Vasocongestion (VC)--accumulation of blood in various tissues
      2. Myotonia (MT)--muscle tension
    6. Continuum, or smooth progression through changes during sexual response
  2. Excitement phase
    1. Men
      1. Sexual stimulus leads to erection (VC)
      2. Skin of scrotum thickens (MT)
      3. Testes elevated (drawn closer to body) (MT)
    2. Both men and women
      1. Nipple erection
      2. Reddening of skin, sex flush (VC)
      3. Increases pulse rate, blood pressure
    3. Women
      1. Increased vaginal lubrication (VC, other tissues nearby put pressure on vaginal walls)
      2. Glans of clitoris swells (VC)--may retract under clitoral hood
      3. Breasts swell, may redden (VC)
      4. Labia majora open and flatten (VC)
      5. Labia minora swell and open (VC)
      6. Upper 2/3 of vagina balloons out (MT)
      7. Cervix and rest of uterus pull up into abdomen (MT)
  3. Plateau phase
    1. Maximum development of VC and MT
    2. Men
      1. Penis fully erect, coronal ridge swollen
      2. Testes engorged (50% increase in size)
      3. Fluid (bulbourethral) appears at tip of penis
    3. Both men and women--maximum breathing rate, pulse rate, blood pressure
    4. Women
      1. Orgasmic platform contracted, swells, thickens (outer 1/3 of vagina and pelvic floor muscles)
      2. Clitoris retracted
      3. Uterus, breasts--maximal changes
      4. Labia minora (change in color--pink to red in women who have had no children, red to maroon in women who have had children)
  4. Orgasmic phase
    1. Sudden release of muscle tension in series of contractions followed by relaxation
    2. Sensations described similarly by both men and women
    3. In males, orgasm usually marked by ejaculation (external evidence)
      1. Contraction of penis and internal structures
      2. 3-5 strong contractions followed by some weaker ones, 0.8 seconds apart
      3. Muscles in back, buttocks, arms, legs, hands, and/or feet may also contract
      4. Spike in pulse rate, breathing rate, blood pressure
    4. In females, usually no external evidence of orgasm
      1. From 3-4 up to 12 contractions of orgasmic platform, 0.8 seconds apart
      2. May be repeated, may follow different patterns and be normal
      3. Freud divided women into those who experienced orgasms after clitoral stimulation (immature) and those who experienced orgasm after vaginal stimulations (mature), but there is no physiological difference between the orgasms that result from either sort of stimulation
      4. Perry and Whipple divided women into those who experienced vulvar (located more in outer tissues) orgasms, those who experienced uterine (more internal tissues) orgasms, and later those who experienced blended orgasms
      5. Actually, women most probably have a range of normal types of orgasmic experience, from clitoral/vulvar to uterine/vaginal and combinations in between
  5. Resolution phase
    1. Heart, pulse, breathing, blood pressure all return to normal
    2. Engorged tissues (VC) shrink to normal size
    3. MT relieved, muscles relax
    4. In men, there is often a refractory period after the resolution phase
      1. Restimulation difficult or impossible
      2. Short time in younger men, longer in older men
    5. No refractory period in women, who may be multiorgasmic, up to 5-20 orgasms, not age dependent
  6. Graphs of sexual responses in men and women
  7. Other researchers
    1. Zilbergeld and Ellison (early 80's)
      1. Expanded Masters and Johnson's work to include subjective experiences of subjects
      2. Stages: sexual desire, arousal (M&M excitement), readiness (VC), orgasm (MT), satisfaction (person's subjective evaluation of experience)
    2. Helen Singer Kaplan (70's and 80's)
      1. Expanded M&J biphasic model (VC and MT) to triphasic model (VC, MT, desire)
      2. Examined effects of aging, drug exposure
      3. Found differences between VC and MT
        1. VC and MT age at different rates
        2. Elderly men may ejaculate (MT) only once per week, but may be able to have many erections/week (VC)
    3. Walen and Roth (90's)
      1. Cognitive model of sexual response incorporating brain functions such as perception, evaluation into model
      2. Graphic image of Walen and Roth model
  8. Sex viewed as work
    1. Attempts to apply measures of business goals achievement to sexual experience
    2. Increased concern about how much, how often, quality of product (orgasm), quality control issues, cost/benefit analysis
    3. Anxiety that results from focus on such objectives may lead to sexual dysfunctions and general unhappiness in sexual relationships
  9. Communication about sex
    1. Lots of public communication about sex, in the media and in groups of people
    2. Private communication between sexual partners still often poor, inadequate to support good sexual relationships