L4.4: Sexual Intercourse

• Coitus or Copulation

  ○ Rhythmic movements that cause the physical movement of the penis, when erected, towards the vagina either for sexual pleasure, reproduction or both.
• Physiology of Sexual Response

  ● Sexual Response among individuals is divided into four important phases:

  1. Excitation
  2. Plateau
  3. Orgasm
  4. Resolution
• EXCITATION

  ● Lasts from a few minutes to several hours.

  ● General Characteristics:

  ○ Vasocongestion

  ○ Increase in vital signs

  ○ Myotonia: increase in muscle tension
• EXCITATION

  MALES

  ● Penile erection

  ● Scrotal sac thickens

  ● Scrotal sac elevation
• EXCITATION

  FEMALES

  ● Vaginal lubrication

  ● Glans clitoris enlarges

  ● Nipples erect (myotonia: contraction)

  ● Breasts enlarge

  ● Inner lips of vulva swell, open, and change in color (darker)

  ● Upper 2/3rds of vagina balloons

  ● Tenting Effect: Cervix and uterus stand up

  ● Angle of the cervical opening becomes more receptive to sperm.
• PLATEAU

  ● Extends to the brink of orgasm.

  ● The changes that began in excitation are more intensified.

  ● General characteristics of males and females continue:

  ○ Vasocongestion

  ○ Continuous increase in vital signs

  ○ Copious perspiration

  ○ Increased Myotonia
• PLATEAU

  MALES

  ● Cowper’s gland secrete fluid through tip of penis (precum)

  ● Scrotum becomes even higher and testicles bigger
• PLATEAU

  FEMALES

  ● Orgasmic platform: Outer third of vagina thickens, swells—condition sine qua non: without it, no orgasm

  ● Tenting complete

  ● Clitoris erect.
• ORGASM

  ● Climax of the sexual response and is the shortest of the phases which generally lasts only a few seconds.

  ● General Characteristics:

  ○ Heart rate

  ○ Blood pressure

  ○ Breathing

  ○ Intense myotonia
• ORGASM

  MALES

  ● Contraction of seminal vesicles, vas deferens, and prostate.

  ● Contraction of urethra and penis: ejaculation.
• ORGASM

  FEMALES

  ● Contractions of orgasmic platform

  ● Contractions of uterus

  ● Several orgasms are possible if stimulation continues.
• RESOLUTION

  ● Body returns to its normal state.

  ● General Characteristics

  ○ Muscles relax

  ○ Breathing becomes normal, as well as vital signs

  ○ Blood goes back to circulation from genitals.
• RESOLUTION

  ● Specifically, for males, they undergo a refractory period.

  ○ It is usually the RECOVERY PHASE after ORGASM when a person might lose interest in sex, or they might not be able to have sex.