Lecture Outline - Chapter 21

21.1. Male Reproductive System (Fig. 21.1; Table 21.1) (p. 392)

1. Testes
   • a. Paired.
   • b. Develop from gonads within abdomen; descend into scrotal sacs.
   • c. Scrotum maintains testes at cooler temperature.
   • d. Sterility, due to too high body temperature, results if testes fail to descend; corrected by surgery.
2. Sperm
   • a. Produced inside tubules in testes.
   • b. Mature in tubular epididymides behind each testes.
   • c. Once mature, sperm propelled into vas deferens by muscle contractions.
   • d. Move from storage in vas deferens to urethra for ejaculation.
3. Penis
   • a. Cylindrical organ in front of scrotum. (Fig. 21.2)
   • b. Spongy tissue inside shaft of penis is flaccid with normal blood flow.
   • c. Erection occurs from increased blood flow filling spongy tissue.
   • d. Impotency is failure to become erect.
4. Semen
   • a. Thick, whitish fluid containing sperm and secretions from three organs. (Table 21.1)
   • b. Two seminal vesicles join two vas deferens; secrete nutrients for sperm at time of ejaculation.
   • c. Ejaculatory duct is single duct leading from two vas deferens; carries semen to urethra.
   • d. Prostate gland surrounds urethra below bladder; secretes milky alkaline fluid that aids sperm motility and survival.
   • e. Prostate gland enlargement is common in older men; constricts urethra and makes urination difficult.
   • f. Bulbourethral glands have mucous secretions with lubricating effect.
5. Ejaculation
   • a. Occurs when sexual arousal reaches peak.
   • b. Orgasm involves rhythmical contractions of ejaculatory duct and urethra, and accompanying physiological and psychological sensations.
   • c. Refractory period is typical time following ejaculation during which erection cannot occur.
6. Testes Produce Sperm and Hormones
   • a. Testes contains sections called lobules, each with one to three coiled seminiferous tubules with total length of 250 meters (Fig. 21.3).
   • b. Spermatogenesis is development of sperm; involves meiosis.
   • c. Sustentacular (Sertoli) cells support, nourish and regulate cells that generate sperm cells.
7. Sperm
   • a. Composed of three parts: head, middle piece, and tail.
   • b. Middle piece and tail have microtubules with 9 + 2 pattern of cilia and flagella.
   • c. Mitochondria ring middle piece and provide energy for sperm movement.
   • d. Head contains acrosome cap with enzymes needed to penetrate outer barriers of egg.
   • e. Normal male produces over 100 million sperm per ejaculation; fewer than 100 reach vicinity of egg; one penetrates.
8. Hormonal Regulation In Males
   • a. Hypothalamus ultimately controls testes by secreting gonadotropic-releasing hormone (GnRH).
   • b. GnRH triggers anterior pituitary to produce two hormones.
   • c. Follicle-stimulating hormone (FSH) promotes spermatogenesis in seminiferous tubules; tubules release hormone inhibin in feedback.
   • d. Interstitial cell-stimulating hormone (ICSH), called luteinizing hormone (LH) in females, controls production of testosterone by interstitial cells.
   • e. Interaction of hormones maintains fairly constant production of sperm and testosterone.
9. Testosterone is the Male Sex Hormone
   • a. Necessary for maturation of sperm.
   • b. Causes and maintains secondary sex characteristics at puberty.
     • i. Growth of beard, underarm, and pubic hair.
     • ii. Larynx and vocal cords enlarge causing voice change.
     • iii. Stimulates muscle growth.
     • iv. Increases sex drive and probably aggressiveness.
     • v. Stimulates sweat and oil glands causing acne and body odor.
   • c. Anabolic steroids used to increase muscles for sports is dangerous.
     • i. Damage to kidneys, circulatory system.
     • ii. Hormone feedback in males triggers reduction in testes, feminization of males.

1. Overview of Female Reproductive System (Fig. 21.5; Table 21.2)
   • a. Ovaries are to each side of uterus in pelvic abdominal cavity.
   • b. Oviducts (fallopian tubes) extend from near ovaries into uterus; sweep up eggs from ovary using cilia lining and wafting fimbria at end of oviducts.
   • c. Uterus is thick-walled muscular organ for nurturing embryo; opening in cervix leads to vagina.
   • d. Vagina is tube with mucosa lining; serves in intercourse and as birth canal.
   • e. External genital organs include labia minora and labia majora enclosing urethral and vaginal openings.
2. Ovaries and Oviducts
   • a. Ovaries
     • i. 3 cm by 1 cm in size.
     • ii. Held in place by ligaments to oviduct and uterus.
     • iii. Each month produces egg that bursts from ovary during ovulation.
   • b. Oviducts are Tubes to the Uterus
     • i. Extend from near ovaries into uterus.
     • ii. Fimbriae are fingerlike ends that sweep up eggs from ovary.
     • iii. Muscular contractions and cilia lining wafting egg toward uterus.
     • iv. Fertilization of egg, oogenesis, and zygote formation usually occurs in oviduct.
     • v. Tubular pregnancies occur when embryo implants in oviduct.
     • vi. Ectopic pregnancy is any implantation outside central body of uterus.
3. Uterus and Vagina
   • a. Uterus
     • i. About size and shape of inverted, flattened pear.
     • ii. Lies above and slants forward over urinary bladder.
     • iii. Oviducts enter uterus anteriorly.
     • iv. Cervix of uterus enters vagina at right angle, posteriorly.
     • v. Stretches from 5 cm wide to over 30 cm with growing baby.
     • vi. Endometrium lining forms placenta with basal layer and functional layer that varies with uterine cycle.
     • vii. Cancer of the cervix usually detected by Pap smear.
     • viii. Hysterectomy is removal of uterus.
   • b. Vagina
     • i. Tube with mucosa lining.
     • ii. Makes 45 degree angle with small of back.
     • iii. Serves in intercourse.
     • iv. Wall extends greatly as birth canal.
4. Females Have External Genitals
   • a. Vulva is term for collective external genitalia. (Fig. 21.6)
   • b. Mons pubis is fatty prominence under pubic hair.
   • c. Labia majora enclose following structures.
   • d. Labia minora extend from vaginal opening to encircle clitoris at front.
   • e. Clitoris is homologous to penis, contains erectile tissue.
   • f. Hymen is ring of tissue that may partially close vaginal opening.

1. Regulation of Cycle
   • a. Hypothalamus secretes gonadotropic-releasing hormone (GnRH).
   • b. GnRH triggers anterior pituitary to produce two hormones.
   • c. Follicle-stimulating hormone (FSH) stimulates follicles in ovary to produce eggs.
   • d. Luteinizing hormone (LH) is involved in uterine cycle.
   • e. Ovaries secrete estrogen and progesterone.
2. The Ovaries Cycle
   • a. Ovaries contain follicles containing oocyte plus surrounding follicle cells.
   • b. Female is born with up to 2 million follicles; reduced to about 350,000 at puberty; only about 400 mature at about one egg per month in reproductive life.
   • c. Stages of Follicle Development
     • i. Primary follicle oocyte duplicates and divides in first part of meiosis to form secondary oocyte at side of fluid-filled cavity.
     • ii. Release of oocyte (egg) is ovulation.
     • iii. Second meiotic division does not occur until fertilization occurs.
     • iv. Remaining follicle cells in ovary develop into corpus luteum which degenerates in ten days if pregnancy does not occur.
     • v. If pregnancy occurs, corpus luteum persists for 3 - 6 months; secretes estrogen and progesterone.
   • d. Follicular phase: during first half of 28-day cycle (day 1 - 13), FSH from anterior pituitary stimulates follicular development in ovary which increases estrogen release into blood; ends with ovulation on about 14th day.
   • e. Luteal phase: during second half of 28-day cycle (day 15 - 28), LH from anterior pituitary promotes development of corpus luteum which secretes progesterone; high progesterone inhibits (negative feedback) LH secretion from anterior pituitary so that corpus luteum begins to degenerate; as luteal phase ends, progesterone drops and menstruation begins.
3. The Uterus Cycles (p. 401)
   • a. Estrogen and Progesterone function to generate the uterine cycle. (Table 21.3) (Fig. 21.9)
   • b. 28 Day Menstrual Cycle:
     • i. Days 1 - 5: low levels of estrogen and progesterone cause endometrium to disintegrate, blood vessels (menses) rupture and flow out of vagina during menstruation.
     • ii. Days 6 - 13: endometrium becomes thicker and more vascular due to increased amounts of estrogen; called proliferative phase.
     • iii. Ovulation occurs on day 14 of 28-day cycle.
     • iv. Days 15 - 28: endometrium doubles in thickness, uterine glands mature and secrete mucus due to production of progesterone by corpus luteum; readies uterus to receive developing embryo.
     • v. If not pregnant, corpus luteum degenerates; lower hormone levels cause uterine lining to break down.
   • c. Pregnancy Follows Fertilization (p. 401)
     • i. Fertilized egg develops as travels down oviduct to uterus.
     • ii. Embryo embeds in endometrial lining (implantation) several days after fertilization.
     • iii. Placenta forms from both maternal and fetal tissues: provides exchange of molecules between fetal and maternal blood.
     • iv. Placenta first produces HCG (human chorionic gonadotropic hormone) to prevent degeneration of corpus luteum.
     • v. With development of placenta, estrogen and progesterone are produced to maintain endometrium lining of uterus and shut down anterior pituitary so no new follicles mature.
4. Estrogen and Progesterone Are Female Sex Hormones
   • a. At puberty, estrogen stimulates the growth of the uterus and vagina and is necessary for egg maturation.
   • b. Causes and maintains secondary sex characteristics at puberty.
     • i. Growth of body, underarm, and pubic hair in female pattern.
     • ii. Stimulates fat deposit under skin for more rounded body.
     • iii. Stimulates breast development.
     • v. Stimulates wider pelvic development and female proportions.
5. Breasts Produce Milk (Fig. 21.11) (p. 403)
   • a. Structure: contains one to two dozen lobules, each with many mammary ducts that end in blind sacs called alveoli.
   • b. Areola (pigmented area of nipple) lacks hair and sweat glands but has saliva-resistant lubricant.
   • c. Prolactin hormone stimulates alveoli to produce milk; feedback inhibition suppresses milk production during pregnancy.
   • d. During couple of days after childbirth and before milk production is underway, a watery, yellowish- white fluid termed colostrum is secreted; contains more protein, less fat.
6. After Menopause the Ovaries Don't Respond (p. 403)
   • a. Between ages 45 and 55, the ovarian and uterine cycles cease.
   • b. Ovaries no longer respond to FSH and LH and stop producing estrogen and progesterone.
   • c. Menstruation becomes irregular; menopause completed after one year of no menstrual cycle.
   • d. Highly variable symptoms include: "hot flashes" from irregular circulation, dizziness, headaches, depression, either insomnia or sleepiness...or no symptoms at all.
   • e. Increased sex drive after menopause may be due to androgens produced by adrenal cortex.

1. Birth Control is Varied
   • a. Most reliable method of birth control is abstinence.
   • b. Birth control methods have variable effectiveness. (Table 21.4; Fig. 21.12)
2. Searching for Other Means of Birth Control
   • a. Barrier methods, including male condom, are on increase due to protection against sexually transmitted diseases.
   • b. Female condom is plastic device lining vagina; anchored with flexible ring.
   • c. Researchers seek an effective "male pill."
     • i. May be based on analogues of gonadotropic-releasing hormone to prevent stimulation of anterior pituitary.
     • ii. Could use inhibin to prevent anterior pituitary from producing FSH.
   • d. RU-486
     • i. Also called mifepristone, or "morning-after" pill.
     • ii. Developed in France; being considered for use in this country.
     • iii. Blocks progesterone receptors in uterine lining; causes uterine lining to slough off preventing implantation or carrying embryo with it.
     • iv. 95% effective; can be used for delayed menstruation.
3. Some Couples are Infertile (p. 406)
   • a. One Out of Four Couples
     • i. American Medical Association estimates 15% of U.S. couples are sterile.
     • ii. Additional 10% have fewer children than they want; assumes couple has been trying to become pregnant but unsuccessful for at least one year.
4. What Causes Infertility?
   • a. In females:
     • i. Blocked oviducts often due to:
       - pelvic inflammatory disease (PID).
       - failure to ovulate due to low body weight.
       - endometriosis where endometrium tissue grows outside uterus in oviducts or on abdominal wall.

       ii. Treatment may involve surgery, medication, or HCG. (Fig. 21.13)
   • b. In males:
     • i. Low sperm count and/or many abnormal sperm due to disease, radiation, chemicals, high testes temperature, or psychoactive drugs.
5. Alternative Methods of Reproduction Are Available (p. 407)
   • a. With sperm and egg donors and adoptive parents, it is possible to have five "parents."
   • b. Artificial Insemination by Donor (AID)
     • i. Sperm from a husband with low sperm count or from a donor is placed inside vagina.
     • ii. Intrauterine insemination (IUI) of woman may involve hormone stimulation of ovaries.
     • iii. In Vitro Fertilization (IVF):
       - Using ultrasound imaging, immature eggs are obtained from a woman's follicles and when mature, mixed with sperm in glassware for fertilization.
       - After 2 - 4 days, developing embryo is inserted into uterus during secretory phase of menstrual cycle for normal sequence of development.
       - costs $3,000 or more; success rate of 15 - 20%.

       iv. Gamete Intrafallopian Transfer (GIFT):

       - same procedure as in vitro fertilization except eggs and sperm placed together in oviduct.

       - less expensive ($1,500), higher success rate than IVF.

       v. Surrogate Mothers:

       - women paid to have babies.

       - Other individuals than adoptive couple may contribute sperm (or eggs) for fertilization.

1. Any disease transmitted by sexual contact is STD; only major STDs covered here.
2. Viral STDs (AIDS, genital warts, herpes, etc.) not treatable with antibiotics.
3. Non-viral diseases (gonorrhea, chlamydia, etc.) do not solicit immune response; therefore no vaccines.
4. AIDS is on the Rise
   • a. Acquired Immune Deficiency Syndrome(AIDS) is due to human immuno-deficiency virus (HIV)
   • b. Attacks helper T lymphocytes; as T cell numbers decrease, patient is more susceptible to other infections.
   • c. New AIDS and other STD cases in U.S. is rising. (p. 408)
   • d. AIDS Symptoms:
     • i. Person with positive AIDS-antibody blood test may be infectious carrier with no other symptoms.
     • ii. Second stage characterized by weight loss, fatigue, fever, diarrhea, loss of memory, judgment, thrush or herpes simplex infections, etc. may occur for 6 - 8 years.
     • iii. "Full-blown AIDS" involves severe weight loss, weakness, and opportunistic infections of Pneumocystis carinii pneumonia, skin cancer, and nervous disorders.
     • iv. Death usually occurs 7 - 9 years after infection.
   • e. AIDS Transmission:
     • i. AIDS passed by blood, semen, and vaginal fluids.
     • ii. In U.S.,main affected groups are homosexual men and intravenous drug users; infections among male homosexuals no longer rising.
     • iii. Percentage of infected heterosexuals is rising; one in five new infections is now a woman.
     • iv. AIDS virus can cross placenta; infants comprise one percent of AIDS cases.
     • v. Long-term mutually monogamous relationship with sexual partner free of infection is relatively safe; unprotected intercourse with multiple partners or single infected partner increases risk; use of latex condom reduces risk.
   • f. AIDS Treatment (p. 410)
     • i. Drugs such as AZT (azidothymidine) interfere with viral replication in cells.
     • ii. HIV attaches to T cells at receptors called CD4 proteins; antibodies against CD4 proteins may attach to T4 cells and prevent this virus from entering.
5. Genital Herpes (p. 410)
   • a. Due to herpes simplex virus type 2; type 1 causes cold sores. (Fig. 21.14)
   • b. Estimated 500,000 new cases per year; about 40 million persons in U.S. total.
   • c. No immediate symptoms; blisters appear within 2 - 20 days.
   • d. Painful ulcers follow blisters rupturing; may take 5 days to 3 weeks to heal.
   • e. Symptoms include fever, pain upon urination, and swollen lymph nodes.
   • f. Dormant virus resides in nerve cells; blisters reoccur with stress.
   • g. May cause eye infection and blindness.
   • h. Infants born vaginally may contract herpes with serious to fatal results.
6. Genital Warts Are Linked to Cancer (p. 411)
   • a. Due to human papillomaviruses (HPVs).
   • b. May lack symptoms or warts may appear on penis or vaginal opening.
   • c. Associated with cancer of cervix and tumors of vulva, anus, vagina, and penis.
   • d. Presently no cure for HPV infection; warts can be treated by surgery.
7. Gonorrhea is Hard to Detect
   • a. Due to diplococcus bacterium Neisseria gonorrheae. (Fig. 21.16)
   • b. 80% of males complain of pain on urination and discharge a thick, greenish yellow fluid within 3 - 5 days of contact; may scar vas deferens.
   • c. Most females are asymptomatic; bacteria spread to oviducts causing pelvic inflammatory disease (PID), which may block or scar oviduct.
   • d. Homosexual males may develop gonorrhea infection of anus.
   • e. Oral sex can cause throat or tonsil infections.
   • f. Infants can be infected during vaginal birth; silver nitrate or antibiotics are standard treatment.
8. Chlamydia Causes PID and Sterility
   • a. Chlamydia trachomatis is parasitic prokaryote unable to produce its own ATP; develop inside other cells that eventually release new infective chlamydia.
   • b. They are the most common cause of NGU (nongonococcal urethritis); increasing at faster rate than gonorrheal infections.
   • c. Men experience mild burning sensation upon urinating and a mucoid discharge 8 - 21 days after exposure.
   • d. Women experience vaginal discharge and symptoms of urinary tract infection; may lead to PID, sterility or ectopic pregnancy.
   • e. Infant may contract chlamydia during vaginal delivery; can cause eye inflammation or pneumonia, perhaps premature birth and stillbirth.
   • f. New clinical tests use DNA probe for detection; some doctors prescribe antibiotics to treat chlamydia for anyone who also has gonorrhea.
   • g. Condoms serve as protection; aided by spermicide with nonoxynol-9.
9. Syphilis Has Three Stages (p. 412)
   • a. Caused by bacterium Treponema pallidum.
   • b. Penicillin is effective antibiotic.
   • c. Three stages may be separated by latent stages of inactivity.
     • i. In primary stage, a chancre (ulcerated sore with hard edges) forms at site of infection.
     • ii. In secondary stage, victim breaks out in rash that does not itch but indicates infection is spread throughout body.
     • iii. In tertiary stage, gummas (large, destructive ulcers) may appear on skin and within internal organs; arteries are weakened; nervous system is damaged leading to psychological symptoms; may lead to death if not treated (usually with penicillin).
     • iv. Congenital syphilis occurs when bacteria cross placenta; child is born blind and/or with malformations.