Physiology of Sexual Response in Men and Women

• The presentation is about the physiology of sexual action and sexual response in men and women.
• Female and male anatomy, the limbic system, the autonomic nervous system, the endocrine basis of female and male sexuality, the physiology of sexual action, and the sexual response in men and women are covered.

Female Anatomy

• The labia majora consist of folds of fat and connective tissue.
• The labia majora extend down from the mons pubis
• The covering skin has hairs along with puberty.
• They protect the labia minora, urethral, and vaginal openings.
• The labia majora are rich in veins and nerves.
• The labia minora are located below the labia majora.
• These are rich in vessels and nerves similar to the labia majora.
• These are covered with a thin layer of epidermis, but have no hair follicles.
• The clitoris is located at the top of the labia minora, described as a short, cylindrical, erectile organ, very rich in veins and nerves which can cause bleeding in tears or injuries.
• The vestibule is a triangular field that occurs where the labia minora open, where the urethra and vagina both open.
• The bilateral Bartholin glands and the hymen are located in the vestibule on the outer part of the vagina.
• The surface is thin and mucosal, which makes it easily irritated by chemicals, heat, discharge, and tight clothing.
• The hymen is an elastic mucous membrane that partially covers the vaginal opening, and has holes to allow menstrual blood to flow out.
• Rarely, it may be completely closed, described as an imperforated hymen, which prevents menstrual blood from flowing, ultimately requiring a hymenotomy.
• Located in the vulva, the Bartholin glands are the largest glands, found on both sides of the vagina and open to the vestibule with its ducts.
• They provide lubrication to the vagina by secreting secretions during sexual stimulation.
• Measuring 8-10cm, the vagina connects the vulva to the uterus.
• It features tubular length, made of muscles and membranes.
• In the unborn, the front and back walls touch.
• The upper part wraps around the cervix from the outside in the form of a ring, where it firmly adheres to the wall of the cervix.
• The part of the cervix that remains inside is called "Porsio".
• The recesses between the porsio and the walls of the vagina are also called "Fornix".
• The vaginal mucosa consists of layers called rugae that allow expansion during childbirth.
• The vaginal mucosa responds to hormones like estrogen and progesterone
• Its pH is acidic to protect from infections
• With the withdrawal of estrogen, the pH shifts to alkaline and senile vaginitis (infection of the vagina due to aging) occurs
• Besides its use as a birth canal, the vagina is a channel through which menstrual blood flows and coitus (sexual intercourse) takes place.

Male Anatomy

• In the male reproductive system, the penis and scrotum form the external reproductive organs.
• Inside the penis are three cylindrical spongios (spongy) layers.
• Included are two corpus cavernosa and the corpus spongiosum.
• The urethra is enclosed in the corpus spongiosum.
• Blood vessels and nerves also pass through the spongios layer,
• Fullness occurs in the blood vessels which causes the characteristic erection
• The tip of the penis is called the glans penis, which is rich in nerve endings and therefore highly sensitive.
• Carrying the testicles and spermatic cords, the scrotum's spermatic cords suspend the testicles, and include blood vessels, nerves, muscle fibrins, and the ductus-vas deferens (passageway of spermatozoa leaving the testicle).
• The spermatic cord enters the abdomen through the inguinal canal.
• In men, the internal reproductive organs form the duct system that provides the storage and transport of the testicles and spermatozoa.
• There is a pair located inside the scrotum, measuring 4cm each.
• Each testicle is suspended inside the scrotum by the spermatic cord (Funiculus spermaticus). Each one is made up of seminal ducts, arteries, veins, lymphatic vessels, and nerves.
• The testicle has two functions:
  • Exocrine Task: Sperm maker
  • Endocrine Function: Hormone secretor

Physiology of Sexual Behavior

• The limbic system, autonomic nervous system, central nervous system, and medulla spinalis are all involved in the physiology of sexual behavior.

• The limbic system controls the affective state and the factors that motivate action, especially in relation to fear, anger, and sexual behavior.

• The limbic system is the brain's network regulating basic functions such as the processing and regulating of emotion and memory, as well as sexual arousal and learning.

• Located on the lower right side of the cerebrum and on either side of the thalamus, the limbic system controls controlling emotional reactions.

• Problems in this part of the brain may trigger psychological processes and cause negative consequences

• The limbic system, also referred to as the emotional brain, consists of the hypothalamus, hippocampus, thalamus, and amygdala. The hypothalamus establishes the relationship between the nervous system and the endocrine system.

• It plays a role in developing behaviors in response to stress and anger, and is a thermoregulation and body temperature regulator

• The connection between the limbic system and sexuality is also located here, and is necessary in providing sexual drive and desire.

• It also directs functions such as sleep patterns, dreaming, and eating.

• The hippocampus processes memory, establishes logical patterns, and strengthens permanent memory.

• It also shapes knowledge of location and direction.

• The thalamus, known as the seat of the sensory centers, controls functions such as hearing, smell, taste and touch, directing important motor behaviors. The amygdala directs instincts, and helps survival reflexes by managing emotions such as sudden anger and fear.

• It produces processes such as struggle, escape, defense and reflex development in situations where the brain sees a threat to itself, and is also effective in creating the sensory response left in the body when people think about them.

• Behaviors necessary for sustaining existence include eating, drinking, anger, rage, fighting, escape and evasion reactions when confronted with an enemy.

• Behaviors related to the continuation of existence and species include behaviours related to coupling, reproduction, offspring care, and nurture.

• Muscle systems have two parts:

  • Somatic Motor System: works voluntarily
  • Autonomous Engine System: works involuntarily

• The nervous system consists of nerve fibers that do not have a myelin sheath.

• It controls the operation of involuntary activities.

• Physiologically, it's divided into two parts:

  • Sympathetic
  • Parasympathetic

• The sympathetic nervous system is mostly activated in times of stress, danger, and excitement, speeding up vessel beats and breathing, expanding brooches, dilating pupils, increasing sweating and blood sugar, constricting capillaries, decreasing saliva secretion, decreasing movements of the stomach and intestines (digestion slows down), slowing down kidney activity (excretion slows down), and relaxing the bladder.

• The parasympathetic nervous system is active when stress, danger, and excitement has passed.

• It allows organs to normalize functioning, increase salivation, accelerate movements of the stomach and intestines (digestion is accelerated), increases kidney activity (excretion accelerates), contracts the bladder, slows down heartbeats and breathing, narrows brooches, shrinks pupils, reduces sweating, decreases blood sugar, and dilates capillaries.

• Sexual response is determined by the interplay of the sexual organs, nervous and endocrine systems, and neurochemical, neurophysiological and psychological processes.

• Diseases, adverse environmental conditions, drugs, alcohol, etc. affect sexual function. Signals from the genitals and other areas are focused in the brain.

• From the brain, chemical and electrical impulses travel through the peripheral nerves and spinal cord to the relevant parts of the body.

• The genitalia and pelvic floor muscles are regulated by the sympathetic and parasympathetic nervous system (pelvic nerves, hypogastric nerve, paravertebral sympathetic chains) and by the (somatic) pudendal nerve. The autonomic nerves regulate blood flow

• Involuntary smooth-muscle contractions accompany arousal, while the somatic nerves control the voluntary or striated muscle responses during orgasm

• Hypothalamus functions include:

  • Coordination of somato-motor and viscera-motor activities
  • Body water balance and control of thirst
  • Body weight control
  • Control of reproduction and sexual behavior
  • Regulation of body temperature
  • Regulation of sleep and wakefulness
  • Controlling Excitement, Fear and Anger
  • Control of the endocrine system

• Brain regions include:

  • Myelencephalon:Medulla oblangata & Reticular formation
  • Metencephalon: Pons & cerebellum
  • Mesencephalon: cerebral agueduct, Corpora quadrigemia, Cerebral peduncles, Red nucleus, & Substansia nigra
  • Diencephalon: Thalamus-Pituitary & epithalamus

• First in estrogen and progesterone are produced by the ovaries under the control of gonadotropin hormones.

• Oestrogen is necessary to maintain the normal condition of the vaginal mucosa, and for lubrication during sexual stimulation.

• Androgens are produced in the ovary and adrenal cortex, and their level changes slightly during ovulation.

Female Sexuality

• Androgen is associated with sexual interest, desire, and desire
• Oestrogen is responsible for the desire for sexual intercourse.
• Progesterone suppresses feelings of active lovemaking and sexual desire, and increases feelings of maternity and cuddling.
• Basic sex hormones include testosterone, dihydrotestosterone, and androstenedione.
• Testosterone and androstenedione are produced in Leydig cells in the testes under the control of the hormone LH.
• Small amounts of androgens (especially dihydrotestosterone) are produced in the adrenal glands.
• In males, testosterone maintains sexual interest and desire and important role in ejaculatory capacity
• There is no direct role in the formation and maintenance of an erection, and erectile dysfunction is not always seen in hypogonadal men
• The pituitary gland secretes follicle stimulating hormone (FSH), luteinizing hormone (LH), growth hormone (GH), melanoctye-stimulating hormone (MSH), prolactin (PRL), adrenocorticotrophic hormone (ACTH) and oxytocin.

Physiology of Sexual Action and Sexual Response

• The human sexual response is normally inactive, but prepared to prepare for intercourse with the opposite sex
• The human sexual response is highly organized, and constitutes a regular biochemical, physiological and psychological process.
• Sexual dysfunction similarity is emphasized between men and women, but men and women experience different things and different forms of pleasure.
• Women exhibit independant psycho-sexual arousal from physical stimuli
• Masters and Johnson divided the male and female sexual response cycles into 4 phases:
• Arousal
• Plateau
• Orgasm
• Thawing (Resolution)
• Later, the sexual desire phase was added
• Phases of the sexual response cycle:
  • Sexual Desire Phase: Sexual desire is the emergence of the sexual urge and the desire to express sexuality, its duration having no definit length or time.
  • Excitation Phase: Characterized mainly by the emergence of erotic feelings and thoughts, erection in the male, and diffuse vasocongestion (blood supply and myotonia) in the female, and can be stimulated by almost any stimulus as it occurs depending on duration and intensity.
  • It may prolong or disappear in case of sexual stimulation that is inappropriate for the person, or if the sexual stimulation is continued intermittently
  • Arousal Phase of females is characterized by: a few minutes or hours that result in the intensity and duration of the stimulus and wetness of the vagina with increased mucus secretions. Wetness and lubrication facilitates the penetration of the penis into the vagina
  • Painful sexual complaints and disorders are often associated with physical causes.
  • Infections, atrophy (decline in the function of the organs) or tumors that may alter is the release from the Bartholin gland causes changes and symptoms.
  • During sexual activity, the clitoris is erect. It can be stimulated by hand contact, by touching erogenous zones such as the breast and vagina, by coitus (sexual intercourse) or by fantasies, i.e. psychologically.
  • A point on the anterior wall of the vagina can be contacted with a diameter of 1 to 3 cm for added pleasure. Stimulation must be maintained.
  • These G spots are stimulated through partner interplay Arousal phase in the Male is characterized by: observable reaction to sexual stimuli like (fantasies, visual stimuli, physical contact) that results hardening/erection of the spongy tissue of the penis as it fills with blood. A normal erection should have both physical and mental stimulation.
  • The glans are covered for some, and must get blood to thicken.
• In the female and Women the Plateau phases lasts for 30 seconds and 3 minutes. Where high arousal and tension occur without falling from where elevation is occurring In Males where a clear message is to appear. With blood pressure and hyperventilation being observed.
  • Orgasm phase, the phase of tension that is released after strong muscle and nerve activation to climax with intense pleasure that lasts just a few seconds resulting in a series of contractions
  • The total duration being for less than just one minute.
    • Arousal and tension may provide the easiest orgasm phase. Where force for vaginal intercourse is no longer needed.
  • A woman who has experienced a period of arousal and has an orgasmic platform, vaginal intercourse becomes easier. However, in women who are not sufficiently aroused, 3 times more force is required for vaginal intercourse.
  • Males experience the muscle and penis to contract involuntarily 3-6 times starting from 0.8 to 1 second intervals. Where semen and vasicular and prostate secrets pass into the urethra. With this. contractions appear to close the bladder. And may secrete about 50 centimeters . All this being controlled by muscle, but not power.
    • During male orgasm, men experience contractions and bodily responses similar to women for couples who express genuine emotion
  • Desolation Stage the release of sexual energy to be completed
• Sexual healing begins with returning back.
  • In women, muscle contraction relaxes, muscle tone returns to normal, and sweating occurs.
  • In men, 50% of the erection disappears in the first stage. Muscle contraction returns to normal. Immediately after orgasm, men experience an aversion to all kinds of sexual stimulation and a sudden discharge of sweat in the body
• Physiological Staging include:
  • Woman:: Excitement, Plataeu, Orgasm and Resolution. See table for details.
  • Men: arousal, Plateau, Orgasm and Resolution. See table for details.