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CHAPTER 22
REPRODUCTIVE SYSTEMS
LEARNING OBJECTIVE 1: State the general functions of the male reproductive
system.
and
LEARNING OBJECTIVE 2: Name the parts of the male reproductive system and
describe the general functions of each part.
Lecture Suggestions and Guidelines
1. Introduce the major functions of the male reproductive system, including
production and maintenance of sperm cells, transportation of these cells, and the
production of male sex hormones.
2. Describe the structure and function of the testes, epididymis, vas deferens,
seminal vesicle, prostate gland, bulbourethral glands, scrotum, and penis.
3. Describe the structure and function of the seminiferous tubules and the interstitial
cells.
Application Question(s)
1. Provide the students with a diagram of the male reproductive organs and ask them
to correctly label the major structures. Describe the functions of each structure.
Answer: The diagram should include the vas deferens, urethra, penis, glans penis,
prepuce, seminal vesicle, ampulla, ejaculatory duct, prostate gland, bulbourethral
gland, epididymis, testis, and scrotum.
Critical Thinking Issue(s)
1. Discuss a vasectomy procedure. Then, divide the class into two factions and
debate any legal, ethical, moral, and economical (medical insurance coverage)
issues associated with this procedure.
Answer: A vasectomy involves the cauterization of the vas deferens to prevent
the emission of viable sperm to the outside of the body. The end result is sterility;
however, sperm are still produced, as is testosterone.
LEARNING OBJECTIVE 3: Outline the process of meiosis and explain how it mixes
up parental genes.
Lecture Suggestions and Guidelines
1. Describe the major steps of meiosis.
2. Discuss the events that lead to tremendous genetic variability.
3. Identify the effects of crossing-over in terms of potential variability.
Application Question(s)
1. Ask students to conduct an experiment that will lend an understanding to the
magnitude of the possible genetic combinations that may occur during meiosis.
Answer: Answers will vary.
Critical Thinking Issue(s)
1. Compare and contrast the events of each phase of meiosis.
Answer: Responses should include a discussion of meiosis I and meiosis II.
LEARNING OBJECTIVE 4: Outline the process of spermatogenesis.
and
LEARNING OBJECTIVE 5: Trace the path sperm cells follow from their site of
formation to the outside.
Lecture Suggestions and Guidelines
1. Describe sustentacular and spermatogenic cells which form seminiferous tubule
epithelium.
2. Discuss the process of meiosis.
3. Describe the production of four sperm cells from each primary spermatocyte.
4. Introduce the formation of a barrier by membranous processes of adjacent
sustentacular cells.
5. Trace the path of sperm cells from seminiferous tubule, through the rete testis,
epididymis, ductus deferens, ejaculatory duct, prostatic urethra, membranous
urethra, and penile urethra, to the body exterior.
Application Question(s)
1. Ask students to develop a flowchart depicting various stages of spermatogenesis.
What major steps should be included?
Answer: The process begins with the formation of spermatogonia, which undergo
mitosis. This results in daughter cells which become primary spermatocytes that
undergo meiosis I and II. The products of these divisions are spermatids, which
undergo spermiogenesis to become mature sperm cells.
Critical Thinking Issue(s)
1. What is the major difference between mitosis and meiosis, in terms of number of
daughter cells produced?
Answer: Meiosis results in the production of four daughter cells, which reflect
two nuclear divisions. In mitosis, each cell divides once to produce two daughter
cells.
LEARNING OBJECTIVE 6: Describe the structure of the penis and explain how its
parts produce an erection.
Lecture Suggestions and Guidelines
1. Describe the shaft’s three layers of erectile tissue.
2. Introduce the terms glans penis, prepuce, root, crura, and bulb.
3. Discuss the process of circumcision.
4. Describe the mechanism of penile erection.
5. Lecture on the mechanism of emission and ejaculation.
Application Question(s)
1. Ask students to develop a set of nine index cards, each of which summarizes a
major step in the mechanism of erection, emission, and ejaculation. Shuffle the
cards and have students rearrange them in the correct sequence.
Answer: The index cards should include the following information: 1) sexual
stimulation; 2) parasympathetic impulses dilate arteries to penis and vein
compression to reduce blood flow away from penis; 3) accumulation of blood
within erectile tissues of penis; 4) penis swells and becomes erect; 5) sexual
stimulation culmination; 6) sympathetic impulses contract smooth muscle; 7)
peristaltic and rhythmic contraction; 8) semen moves into urethra; and 9) semen is
forcefully expelled.
Critical Thinking Issue(s)
1. Discuss various factors, which may lead to impotence.
Answer: Impotence may be caused by a number of factors. Discuss the role of
fatigue, stress, distraction, premature ejaculation, alcoholism, urologic disorders,
diabetes mellitus, medications, etc.
LEARNING OBJECTIVE 7: Explain how hormones control the activities of the male
reproductive organs and the development of male secondary sex characteristics.
Lecture Suggestions and Guidelines
1. Discuss the roles of the hypothalamic and pituitary hormones, including GnRH,
GSH, and ICSH.
2. Lecture on the most important androgen, testosterone, and its conversion into
dihydrotestosterone.
3. Describe the actions of testosterone.
4. Discuss the negative feedback mechanism, which regulates testosterone
concentration.
5. Give examples of the male secondary sexual characteristics.
Application Question(s)
1. What would be the result of a failure of the testes to descend from the abdomen
into the scrotum?
Answer: Sterility would most likely result, since the temperature in the abdomen,
when compared to the temperature in the scrotum, is too warm for sperm too fully
mature.
Critical Thinking Issue(s)
1. Ask students to write a short report on their opinions of the relationship between
testosterone levels and male aggression.
Answer: Responses will vary.
LEARNING OBJECTIVE 8: State the general functions of the female reproductive
system.
and
LEARNING OBJECTIVE 9: Name the parts of the female reproductive system and
describe the general functions of each part.
Lecture Suggestions and Guidelines
1. Describe the structure and function of the ovaries, including ovary attachments,
ovary descent, and primordial follicles.
2. Discuss the location, structure, and function of the uterine tubes, uterus, and
vagina, which comprise the female internal accessory organs.
3. Lecture on the location, structure, and function of the female external
reproductive organs, including the labia majora, labia minora, clitoris, and
vestibule.
4. Describe the mechanics of female erection, lubrication, and orgasm.
Application Question(s)
1. Provide students with a diagram of the female reproductive organs and ask them
to correctly label the major structures. Describe the functions of each structure.
Answer: The diagram should include the fallopian tube, ovary, uterus, urethra,
clitoris, labia minora, labia majora, vaginal orifice, fimbriae, fornix, cervix, and
vagina.
Critical Thinking Issue(s)
1. What is a Pap smear and why is it clinically significant?
Answer: The Pap smear is a diagnostic test named for George Papanicolaou, its
creator. Cervical epithelial cells are carefully removed via a swab and examined
for size, shape, and number. Any abnormalities in these cervical lining cells are
noted, as they may indicate one of several stages of cancer. A biopsy of
suspicious tissue generally follows.
LEARNING OBJECTIVE 10: Outline the process of oogenesis.
Lecture Suggestions and Guidelines
1. Trace the meiotic events of oogenesis from the oogonium through the
development of a first and second polar body.
2. Introduce the term zygote.
3. Describe the ovarian cycle.
4. Describe the events associated with follicle maturation.
5. Discuss the process of ovulation and trace the pathway of an oocyte.
Application Question(s)
1. Ask students to sketch a flow diagram depicting the major events of oogenesis.
Answer: Sketches may vary slightly but should include the mitosis of an ovarian
cell to produce a primary oocyte. The primary oocyte undergoes meiosis to form a
first polar body and a secondary oocyte. If the secondary oocyte is fertilized, it
undergoes meiosis again to produce a zygote and another polar body. The two
polar bodies eventually disintegrate, the zygote may mature into an embryo.
Critical Thinking Issue(s)
1. During fertilization, what is the basic difference between the formation of
identical twins when compared to fraternal twins?
Answer: Identical twins are the result of one zygote spontaneously splitting in
two; fraternal twins are the result of two ova being fertilized simultaneously by
two different sperm.
LEARNING OBJECTIVE 11: Describe how hormones control the activities of the
female reproductive organs and the development of female secondary sex characteristics.
Lecture Suggestions and Guidelines
1. Introduce the two most important female sex hormones, estrogen and
progesterone.
2. Describe the roles of GnRH, FSH, and LH.
3. Give examples of the female secondary sexual characteristics.
Application Question(s)
1. What might be a concern, related to this learning objective, for young, female
athletes who train vigorously.
Answer: Irregular menstrual flow and decreased estrogen levels, which may lead
to osteoporosis, are concerns for serious, competitive, female athletes in training.
Critical Thinking Issue(s)
1. Ask students to develop a flowchart, which illustrates various aspects of the
control of female secondary sex characteristics, development.
Answer: The flowchart should illustrate the influence of the following:
hypothalamus, GnRH, pituitary gland, gonadotropins (particularly FSH and LH),
and the ovaries.
LEARNING OBJECTIVE 12: Describe the major events that occur during a
reproductive cycle.
Lecture Suggestions and Guidelines
1. Discuss the effects of hormones on the menstrual cycle.
2. Describe the major events of menses.
3. Describe the major events of the proliferative stage.
4. Describe the major events of the secretory stage.
5. Explain the final events of the menstrual cycle when fertilization does not occur.
6. Discuss menopause.
Application Question(s)
1. Ask students to prepare a set of ten index cards, each of which summarizes a
major event in a menstrual cycle. Shuffle the index cards and have students
rearrange them in the correct sequence.
Answer: The index cards should contain information on the following: 1)
secretion of FSH and LH; 2) follicle stimulation; 3) estrogen secretion; 4)
stimulation of ovulation by LH; 5) emergence of corpus luteum cells; 6)
degeneration of corpus luteum; 7) constriction of uterine blood vessels; 8)
disintegration and sloughing off of uterine lining; 9) secretion of FSH and LH
once again; and 10) repeating of menstrual cycle.
Critical Thinking Issue(s);
1. Distinguish among the terms amenorrhea, menorrhagia, and metrorrhagia. What
are some common causes of each?
Answer: Amenorrhea refers to an absence of menstrual periods. Possible causes
include hormonal imbalance, ovarian or uterine disease, or emotional upset.
Menorrhagia refers to excessive or prolonged bleeding during menstruation,
which may be linked to uterine tumors and a failure to ovulate. It could be caused
by PID or a hormonal imbalance. Metrorrhagia is bleeding between menstrual
periods or extreme irregularity in the cycle. The cause is often a hormonal
imbalance.
LEARNING OBJECTIVE 13: List several methods of birth control and describe the
relative effectiveness of each method.
Lecture Suggestions and Guidelines
1. Describe a variety of birth control methods, including coitus interruptus, rhythm
method, mechanical barriers, chemical barriers, oral contraceptives, injectable
contraceptives, contraceptive implants, intrauterine devices, and surgical methods.
2. Give examples of commercially available birth control products and comment on
the advantages and disadvantages of each.
3. Discuss sexually transmitted diseases.
Application Question(s)
1. Prepare a set of index cards, each card containing the name of a birth control
method on the front. As you reveal the method name, ask students to respond with
as much detail about the method as they can.
Answer: The students’ responses should include the birth control method
type, (for example, hormonal, barrier, surgical, etc.), mechanism, advantages,
disadvantages, and estimated reliability.
Critical Thinking Issue(s)
1. Divide the class into two factions to debate the legal, moral, ethical, and
economical ramifications of various birth control methods.
Answer: Responses will vary.
LEARNING OBJECTIVE 14: List general symptoms of sexually transmitted diseases.
Lecture Suggestions and Guidelines
1. Describe why STDs are sometimes referred to as “silent infections.”
2. Discuss the more common signs and symptoms of STDs.
3. Identify the major STDs based on cause, symptoms, treatments, and
complications.
Application Question(s)
1. Ask students to perform research on a particular sexually transmitted disease in a
designated geographic area. Discuss the demographics of the population, the
socioeconomic status of the patients, the incidence of a particular disease, etc.
Answer: Responses will vary, but should ensure patient confidentiality.
Critical Thinking Issue(s)
1. Ask students to develop a community education plan that would be of value in
deterring the spread of sexually transmitted diseases. Who would you offer the
program to? Where would the education be held? Who would be involved?
Answer: Recommendations will vary.
RELATED DISEASES OF HOMEOSTATIC INSTABILITY
1. Pelvic Inflammatory Disease—A condition that may be bacterial, viral, fungal, or
parasitic in origin in which the pelvic organs become inflamed. This can lead to
subsequent infection of the cervix, endometrium, fallopian tubes, and ovaries.
Signs and symptoms include lower abdominal pain, fever, and discharge.
2. Gonorrhea—A bacterial infection caused by gonococcus through sexual
intercourse. Symptoms occur within 2–8 days after infection. In females, the
disease may spread to the cervix. In males, the disease may lead to acute urethritis
or prostatitis. Mother can pass on to child during childbirth via the eyes.
3. Genital Herpes—Herpes Simplex II, which affects the mucus membranes of the
genital tract. Symptoms appear within three weeks after exposure. The virus
remains dormant until reactivated.
SUGGESTIONS FOR ADDITIONAL READING
Aldous, Peter. December 2, 1994. A booster for contraceptive vaccines. Science, vol.
266. By directing the immune system to produce antibodies to block molecules that
function in fertilization, contraceptive vaccines, for both men and women, may be
possible.
Flieger, Ken. April 1992. Prostate problems plague older men. FDA Consumer. An
enlarged prostate is a common problem but it can be treated if the problem is caught
early.
Friedmann, Theodore. June 1997. Overcoming the Obstacles to Gene Therapy. Scientific
America.
Garnick, Marc B. April 1994. The dilemmas of prostate cancer. Scientific American. Do
the risks of aggressive treatment for early prostate cancer outweigh the benefits? This
question is one of several unresolved issues found by those who treat, and those who
have prostate cancer.
Holloway, Marguerite. April 1994. An epidemic ignored. Scientific American.
Endometriosis is linked to dioxin and immunologic dysfunction.
Howards, S. S. February 2, 1995. Current concepts: Treatment of male infertility. New
England Journal of Medicine, vol. 332. A comprehensive and timely review of
treatments for male infertility.
Lewis, Ricki. April 1995. Genital warts: Treatment choices increase. FDA Consumer.
Genital warts can be unsightly and embarrassing, but they aren’t dangerous.
Miki, Yoshio, et al. October 7, 1994. A strong candidate for the breast and ovarian cancer
susceptibility gene BRCA1. Science, vol. 266. Discovery of this gene will save some
women from unneeded surgery, and alert others to its necessity.
Science, vol. 259. January 29, 1993. This issue contains several excellent articles on
breast cancer.
Seppa, Nathan. December 7, 2002. Jarring Result–Extreme biking can hurt men’s
fertility. Science News.
Service, Robert F. December 4, 1994. Contraceptive methods go back to the basics.
Science, vol. 266. More male contraceptives are being developed.
Travis, John. March 27, 2004. It’s time! Fetal lungs tell mom when to deliver baby.
Science News, vol. 165, no. 13, pg. 198.