Download LEARNING OBJECTIVE 3: Outline the process of meiosis and

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.
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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.
2.
3.
4.
5.
Describe the shaft’s three layers of erectile tissue.
Introduce the terms glans penis, prepuce, root, crura, and bulb.
Discuss the process of circumcision.
Describe the mechanism of penile erection.
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.
2.
3.
4.
5.
Discuss the roles of the hypothalamic and pituitary hormones, including GnRH, GSH, and ICSH.
Lecture on the most important androgen, testosterone, and its conversion into dihydrotestosterone.
Describe the actions of testosterone.
Discuss the negative feedback mechanism, which regulates testosterone concentration.
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.
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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.
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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 menstrual cycle.
Lecture Suggestions and Guidelines
1.
2.
3.
4.
5.
6.
Discuss the effects of hormones on the menstrual cycle.
Describe the major events of menses.
Describe the major events of the proliferative stage.
Describe the major events of the secretory stage.
Explain the final events of the menstrual cycle when fertilization does not occur.
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: Describe the hormonal changes in the maternal body during pregnancy.
and
LEARNING OBJECTIVE 14: Describe the birth process and explain the role of hormones in this
process.
Lecture Suggestions and Guidelines
1. Discuss the transport of sex cells.
2. Lecture on the events of the fertilization process.
3. Describe early embryonic development.
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4. Discuss hormonal changes during pregnancy, including the production of hCG, the effects of estrogen and
progesterone on FSH and LH, the role of relaxin, and the effects of lactogen and aldosterone.
5. Address other changes, which occur in the female body due to pregnancy, e.g., changes in blood pressure,
cardiac output, breathing rate, urine production, and dietary needs.
6. Discuss the major events of the birthing process.
Application Question(s)
1. Ask female students with children to devise a master list of any changes their bodies experienced during
pregnancy and after delivery to the present. Include physical changes, emotional changes, changes in attitude,
diet, etc. Then, ask the fathers in the class to compose a list of their observations of changes they perceived in
their spouse during the same time frames. Do the lists composed by females and males agree?
Answer: Responses will vary. This exercise is especially interesting if the students’ spouses are invited to the
classroom for discussion.
Critical Thinking Issue(s)
1. Explain the process of in vitro fertilization.
Answer: In vitro fertilization can occur when the ova are removed from the body through the abdomen and
combined with donor sperm. This combination can then be placed immediately into the fallopian tube for
fertilization, or the solution is fertilized and then placed in the uterus for subsequent development.
LEARNING OBJECTIVE 15: 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 16: 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.
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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.
Service, Robert F. December 4, 1994. Contraceptive methods go back to the basics. Science, vol. 266. More male
contraceptives are being developed.
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