Human Sexual Behavior Chapter 2
Human Sexual Behavior Chapter 2 82679 - PSYC 3060 - 001
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This 8 page Class Notes was uploaded by Brenna Biggs on Saturday February 6, 2016. The Class Notes belongs to 82679 - PSYC 3060 - 001 at Clemson University taught by Bruce Michael King in Fall 2015. Since its upload, it has received 15 views. For similar materials see Human Sexual Behavior in Psychlogy at Clemson University.
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Date Created: 02/06/16
Human Sexual Behavior Chapter 2 Our Sexual and Reproductive Anatomy Men are more likely than women to use slang terms when referring to the genitalia EXTERNAL FEMALE ANATOMY External female genitalia is collectively known as the vulva Mons veneris, the labia majora, the labia minora, the clitoris, and the vagina and urethral openings The Mons Veneris Soft layer of fatty tissue overlaying the area where the pubic bones come together Sensitivity to touch depends on the density of nerve endings in an area of skin Soft layer of fatty tissue cushions the pubic region during intercourse Purpose of pubic hair is unknown Until the 1970s, it was uncommon for women to shave their pubic area Labia Consists of two outer (labia majora) and two inner (labia minora) elongated folds of skin, which in the sexually not stimulated state, cover the vaginal and urethral openings The labia majora extend from the mons to the hairless bit of skin between the vaginal opening and the anus, called the perineum The outer surfaces of the labia majora become covered with hair during puberty After childbirth it is normal for the labia majora to remain separated to some extent in the unstimulated state Labia minora are located between, sometimes protrude beyond, the labia majora Pinkish and hairless Two lips meet at the top to form the clitoral hood, very sensitive to touch Bartholin’s glands are located at the base of the labia minora Contribute a few drops of an alkaline fluid to the inner surfaces via ducts Does not make a significant contribution to vaginal lubrication Helps to counteract the normal acidity of the outer vagina Clitoris Develops from the same embryonic tissue as the penis, but has twice as many nerve endings Only visible portion is the glans Body of the clitoris is located beneath the clitoral hood Contains two parallel cylinders of spongy tissue called corpora cavernosa Toward the rear, form much larger structures called crura that fan out and attach to the pubic bone Spongy tissues of the clitoris become engorged with blood during sexual arousal If sexual stimulation continues, the clitoris pulls back against the pubic bone and disappears from view beneath the clitoral hood Surgical removal of the clitoris was sometimes performed during Victorian times to prevent girls from masturbating and growing up “oversexed” Thick secretions called smegma can accumulate beneath the clitoral hood and result in discomfort during sexual intercourse The Vaginal Opening Vaginal and urethral openings are visible only if the labia minora are parted Area between the two labia minora is sometimes referred to as the vestibular area Vaginal opening has lots of nerve endings Surrounded by the bulbocavernosus muscle, a ring of sphincter muscles Vestibular bulbs are located under the sphincter muscles on both sides of the vaginal opening Help the vagina grip the penis by swelling with blood during sexual arousal Hymen may partially cover the vaginal opening in sexually inexperienced Found only in human females The Urethral Opening Urine passes from the bladder through a small tube called the urethra and out the urethral opening, which is located below the clitoris and above the vaginal opening A woman’s urinary system is not related to her reproductive system The Breasts Not part of a woman’s reproductive system Develop at puberty as a result of increasing levels of the hormone estrogen Each adult breast consists of 15 to 20 mammary glands A separate duct connects each gland to the nipple Made up of smooth muscle fibers and also has lots of nerve fibers The smooth muscle fibers contract and nipples become erect when sexually aroused Small bumps on the areola are glands that secrete oil to keep the nipples lubricated during breastfeeding A hormone called prolactin from the pituitary gland causes the mammary glands to start producing milk in the late stage of pregnancy A baby’s sucking on the nipple causes the pituitary to produce oxytocin, which results in the ejection of milk Breast size is determined by the amount of fatty tissue packed between the glands Plastic surgeons implant pouches of silicone to increase breast size Complications are common; most implants begin to leak Painful fibrous capsules sometimes form around the implant, making the breast hard, tight, unnatural in appearance, and often requiring additional surgery Breast Cancer and Examination Breast cancer is the most common type of cancer in women One in eight American women will develop breast cancer in her lifetime Men can get breast cancer too High risk factors: family history of breast cancer, extensive dense breast tissue, being older than 50 years, never having given birth or having the first child after age 30, starting menstruation before age 12, or undergoing menopause after age 55 Majority of breast cancer cases are fueled by the female hormone estrogen With early detection, there is a 96% survival rate American Cancer Society recommends women to examine their breasts every month starting at age 20 and have a mammogram every year starting at age of 40 Symptoms are usually painless Many surgical procedures might be performed 1) Radical mastectomy: the entire breast, underlying muscle, and lymph nodes are removed 2) Simple mastectomy: only the breast is removed 3) Lumpectomy: only the lump and some surrounding tissue are removed Chemotherapy, radiation therapy, and hormonal therapy are also used INTERNAL FEMALE ANATOMY Female’s reproductive system: the vagina, uterus, Fallopian tubes, and ovaries Vagina serves as a depository for the man’s sperm Ovaries produce eggs Egg and sperm unite to start a new living being in a Fallopian tube Fertilized egg then travels through the tube and implants itself within the uterus The Vagina Internal structure located behind the bladder and in front of the rectum Capable of expanding to about 4 inches in diameter Walls of the inner two thirds of the vagina begin to expand to accommodate a penis when a woman becomes aroused Vaginal walls have three layers Inner layer has a soft mucosal surface similar to the inside of the mouth Rising levels of female hormones at puberty cause the vaginal walls to thicken and become more elastic Vaginal lubrication results from the walls of the vagina becoming filled with blood, with the resulting pressure causing fluid to be secreted from the mucosal lining Vagina is a selfcleansing organ Walls of the vagina continually secrete fluids to help maintain an acidic environment Walls of the inner two thirds of the vagina are insensitive to touch, has few nerve endings Surrounded by the pubococcygeus (PC) muscle, which has more nerve endings Some sex therapists suggest daily Kegel exercises to strengthen this muscle to enhance pleasure during sexual intercourse and for better bladder control Second onefifth of the front wall: some women have a small, very sensitive spot called the Grafenberg (G) spot Only 10% or fewer women have this area of heightened sensitivity The Uterus Where a fertilized egg will attach itself and become an embryo Cervix, the narrow end of the uterus, projects into the back of the vagina Fundus: broad part of the uterus Ligaments hold the uterus in the pelvic cavity at a 90degree angle to the vagina Uterus has three layers Innermost endometrium: where the fertilized egg implants Myometrium: a strong middle layer of muscles, contracts during labor Perimetrium: an external cover Endometrium thickens and becomes rich in blood vessels after ovulation If fertilization does not occur, it is sloughed off and discharged from the woman’s body during menstruation Cervical opening dilates to 10 centimeters at childbirth to allow delivery of the baby Cancer of the Female Reproductive System Cervix is a common site for cancer in women Can have this cancer at almost any age High risk: those who began having sexual intercourse at an early age, who have had numerous sexual partners, whose partners have had numerous sexual partners Rare among celibate women Pelvic exam and Pap smear test is used to check for cervical cancer Annual checkups should begin at age 21 or, if they have not yet engaged in sexual intercourse, 3 years later than when they do start Cancer of the endometrium is also very common First symptom is abnormal vaginal bleeding Should cancer be found, the doctor will probably recommend a hysterectomy Ovarian cancer is rare but deadly Most cases are found in postmenopausal women or women approaching menopause Highest risk factor is a family history of ovarian cancer Treatment usually involves removal of the ovaries and radiation The Fallopian Tubes Extend 4 inches laterally from both sides of the uterus No direct physical connection between the Fallopian tubes and the ovaries Fingerlike projections at the end of the tubes (fimbriae) brush against the ovaries After an egg is expelled, it is picked up by one of the fimbriae If a sperm fertilizes the egg, it will usually do so within the tube Egg continues its 34 day trip though the tube; implants itself in the endometrium The Ovaries Female gonads develop from the same embryonic tissue as the male gonads Suspended by ligaments on both sides of the uterus Two functions: to produce eggs, to produce female hormones At birth, a girl has all the immature eggs that she will ever have (300,000400,000) Primary follicle: surrounds egg; matures into Graafian follicle; process ends at menopause EXTERNAL MALE ANATOMY The Penis: Outer Appearance Has both reproductive and urinary function Hardens and becomes erect during sexual stimulation, enabling penetration of the vagina Average size of the penis is 3.75 inches in length when flaccid About 4.5 to 6.0 inches when erect At birth the foreskin folds over the glans, but many men have had their foreskin cut off in circumcision The Penis: Internal Structure Three parts: body or shaft, glans, and root Shaft consists of three parallel cylinders of spongy tissue, two corpora cavernosa on top and a corpus spongiosum on the bottom Each is contained in its own fibrous sheath Spongy body expands greatly in front to form the round, smooth glans Raised rim at the border of the shaft and glans is called the corona Most sensitive to touch of any part of the penis Urethra runs through the corpus spongiosum Root of the penis consists of the expanded ends of the cavernous bodies, which fan out to form crura and attach to the pubic bone When a man becomes sexually aroused, the arteries going to the penis dilate and the many cavities of the cavernous and spongy bodies fill with blood Valves in the veins that drain the penis simultaneously close Male Circumcision The reason for circumcision most commonly given by American physicians is to ensure proper hygiene Have a much lower chance of getting HIV, human papillomavirus infections, and other STDs if they have unprotected vaginal intercourse with infected partners The Scrotum Sac located beneath the penis is called the scrotum Holds the testicles outside of the body cavity Sperm are produced at several degrees lower than the normal body temperature When cold, muscle fibers contract to draw the testicles closer to the body cavity When hot, muscle fibers relax and they are suspended farther away INTERNAL MALE ANATOMY Male internal reproductive system: testicles, duct system to transport sperm out of the body, prostate gland and seminal vesicles that produce the fluid in which the sperm are mixed, and the Cowper’s glands The Testicles Two functions: to produce sperm, to produce male hormones Millions of new sperm are produced each day in several hundred seminiferous tubules In between seminiferous tubules are interstitial cells of Leydig, which produce male hormones Most important hormone is testosterone Sterility and increased risk of hernia and cancer of the testicles can result from undescended testicles Each testicle is suspended in the scrotum by the spermatic cord, a tubelike structure that contains blood vessels, nerves, the vas deferens, and a muscle that helps to raise and lower the testicles Each testicle is enclosed in a tight fibrous sheath and are very sensitive to pressure Testicular Cancer and SelfExamination Cancer of the testicles is not very common High risk: testicles did not descend into the scrotum before the age of 10, had an early puberty, and those with inguinal hernias Most common symptom is a small lump or a testicle that is slightly enlarged The Duct System After sperm are produced in the seminiferous tubules, they pass through a fourpart duct system before being expelled from the penis during as ejaculation Seminiferous tubules converge to form the epididymis Sperm mature (become more fertile and achieve greater motility) in the epididymis From here the sperm pass into the vas deferens Vas begin in the scrotum, then travel through the spermatic cord and enter the abdominal cavity through the inguinal canal During orgasm, rhythmic muscular contractions force the sperm into the ejaculatory ducts, shortpaired tubes that run through the prostate gland, mixed with fluids from the prostate and seminal vesicles to form semen Ducts open into the urethra Sphincter muscles surround the part of the urethra coming from the bladder Involuntarily contract during an erection so urine does not mix with semen The Prostate Gland and Seminal Vesicles Most of the volume is seminal fluid from the seminal vesicles and the prostate gland Prostate secretes an antibiotic, possibly to protect both people from infection The Cowper’s Glands Two peasized structures located beneath the prostate Secrete a few drops of an alkaline fluid Fluid neutralizes the normal acidity of the urethra so the sperm are not destroyed when passing through the penis during ejaculation Prostate Problems and Examination Cancer of the prostate is the most common nonskin cancer among men in the United States Rates are considerably higher among African American men than among white men Cause of prostate cancer is still unclear Men show no symptoms in the early stages Today, computeraided surgery can often target the prostate tissue without damaging vital nerves Traditional method for diagnosing prostate cancer has been the rectal examination or a blood test KEY TERMS Androgens Perinuem Areola Primary follicle Bartholin’s glands Prolactin Breasts Prostate gland Bulb (of penis) Pubic hair Bulbocavernosus muscle Pubococcygeus (PC) muscle Cervix Root (of penis) Circumcision Scrotum Clitoral hood Semen Clitoris Seminal vesicles Corona Seminiferous tubules Corpora cavernosa Sensuality Corpus spongiosum Shaft Cowper’s glands Smegma Crura Sperm Ejaculatory ducts Spermatic cord Endometrium Testicles Epididymis Urethra Fallopian tubes Uterus Fimbria Vagina Foreskin Vas deferens Fundus Vestibular area Genitalia Vestibular bulbs Glans Vulva Graafian follicle Grafenberg (G) spot Hymen Introitus Kegel exercises Labia majora Labia minora Leydig, interstitial cells of Mammary glands Mammogram Mons veneris Nipple Os Ova (ovum) Ovary Oxytocin Pap smear Pelvic exam Penis
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