Introduction

Chapter 1. Chapter 30: Reproductive System

Interactive Study Guide
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Welcome to the Interactive Study Guide for Chapter 30: Reproductive System! This Study Guide will help you master your understanding of the chapter's Driving Questions, using interactive Infographics and activities, as well as targeted assessment questions. Click "Next" to get started, or select a Driving Question from the drop-down menu to the right.

Too Many Multiples?

The birth of octuplets raises questions about the fertility business

DRIVING QUESTIONS

  • What is the anatomy of the male and female reproductive tracts?
  • What hormones participate in reproduction, and how do they work?
  • What are the different types of assisted reproduction, and how do they work?

Driving Question 1

What is the anatomy of the male and female reproductive tracts?

Why should you care?

Considering how much of our sense of self is connected to our gender, it's surprising how little many people know about the human reproductive system and their own body. Understanding what the reproductive organs do and where they are is the first step toward taking an active role in your reproductive health. Even if you are not a woman, it important to understand the female reproductive system, if only because it will give you more empathy with 50% of the people you encounter every day.

The male reproductive system is based on the female reproductive system; if no androgen hormones are present in a human with X and Y chromosomes, that human will most likely develop the reproductive features of a female. If you consider this fact, it is easier to understand the male reproductive system. For example, if you consider that the testes and vasa deferentia (pl. of vas deferens) are analogous to the ovaries and oviducts in women, the roundabout route that the vas deferens makes from testis to urethra makes a little more sense. Overall, the reasons for learning about the male reproductive system are the same as for the female reproductive system: you should know how each system works both to control your reproductive health and to be sympathetic with the health concerns of all sexes.

A fertile man produces millions of sperm cells per day. The image of sperm racing each other toward the egg has become a trite joke, but it is grounded in truth. Of the vast number of sperm ejaculated, only the strongest hundred or fewer survive the race to the egg, and only one will fertilize it. Understanding how fertilization works and where it occurs is important knowledge for any responsible adult.

What should you know?

To fully answer this Driving Question, you should be able to:

  1. Identify and differentiate between the main parts of the female reproductive system.
  2. Identify and differentiate between the main parts of the male reproductive system.
  3. Describe the events that lead to fertilization.

Infographic Focus

The Infographics most pertinent to the Driving Question are 30.1 to 30.3 and 30.7.

Test Your Vocabulary

Choose the correct term for each of the following definitions:

Term Definition
A class of sex hormones, including testosterone, that is present in higher levels in men than in women and causes male-associated traits like deep voice, growth of facial hair, and defined musculature.
The mixture of fluid and sperm that is ejaculated from the penis.
A female sex hormone produced by endocrine cells in the ovaries (particularly in the cells of the corpus luteum) that prepares and maintains the uterus for pregnancy.
Paired female reproductive organs; the ovaries contain eggs and produce estrogen and progesterone.
Tubes in which sperm mature and are stored before ejaculation.
The fusion of an egg and a sperm.
Paired male reproductive organs, which contain sperm and produce androgens, primarily testosterone.
A female sex hormone produced by the ovaries.
Coiled structures that constitute the bulk of the testes and in which sperm develop.
A tube that connects the bladder to the genitals and carries urine out of the body. In males, the urethra travels through the penis and also carries sperm.
The muscular organ in females in which a fetus develops.
The first part of the female reproductive tract, extending up to the cervix; also known as the birth canal.
The sac that holds the testes.
The tube connecting an ovary and the uterus in females. Eggs are ovulated into and fertilized within the oviducts.
The opening or neck of the uterus, where sperm enter and babies exit.
The lining of the uterus.
One of a pair of tubes that carry sperm from the testes to the urethra.
The primary male sex hormone, which stimulates the development of masculine features and plays a key role in sperm development.
Table
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Identify and differentiate between the main parts of the female reproductive system.

1.

In the table below, match each organ of the female reproductive system to its function. Then match the organ to its corresponding letter on Infographic 30.1.

Functions Organs Location
produces eggs and some sex hormones
site of embryo implantation and fetal development
controls passage of sperm as they travel to the egg
entrance to the female reproductive tract
site of fertilization and egg release
Table
2
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Identify and differentiate between the main parts of the male reproductive system.

2.

In the table below, match each organ of the male reproductive system to its function. Then match the organ to its corresponding letter on Infographic 30.2.

Functions Organs Location
contains paired male sex organs
carries sperm out of body
carries sperm to the urethra
delivers sperm to the female reproductive system
stores mature sperm
ducts that are the site of sperm development
produces sperm and sex hormones
Table
2
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Describe the events that lead to fertilization.

3.

What is the first step in fertilization?

Ovulation is the first step in fertilization; that is, a viable egg must be released from the ovary into the oviduct.

Review Questions

5.

Normally, eggs are fertilized in the ____________, and the resulting embryos implant themselves in the ____________.

A.
B.
C.
D.
E.

2
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Driving Question 2

What hormones participate in reproduction, and how do they work?

Why should you care?

The menstrual cycle, governed by an array of hormones, causes a predictable cycle of changes in a fertile woman's body. Chances are that you already care about the menstrual cycle, but you may not be aware of all of the changes that happen during it. Understanding the mechanics of the menstrual cycle will help you understand how fertilization occurs as well as how hormonal contraception works.

The fact that hormones support pregnancy (or perhaps prevent it) gave rise to the idea of hormone-based contraception. Imbalances in the hormones that support pregnancy are also the basis for many kinds of infertility.

What should you know?

To fully answer this Driving Question, you should be able to:

  1. Describe the functions and sources of the hormones that regulate the menstrual cycle.
  2. Explain how the ovaries, hormone levels, and endometrium thickness change throughout the menstrual cycle.
  3. Describe the timeline of events leading from ovulation to implantation of an embryo.
  4. Explain how hormones regulate pregnancy.
  5. Predict how hormone levels could be artificially modified to prevent pregnancy.

Infographic Focus

The Infographics most pertinent to the Driving Question are 30.5 and 30.6 and Table 30.1.

Test Your Vocabulary

Choose the correct term for each of the following definitions:

Term Definition
The gland in the brain that secretes luteinizing hormone and follicle-stimulating hormone.
A fertilized egg.
The prevention of pregnancy through physical, surgical, or hormonal methods.
A female sex hormone produced by endocrine cells in the ovaries (particularly in the cells of the corpus luteum) that prepares and maintains the uterus for pregnancy.
A hormone secreted by the anterior pituitary. In females, a surge of LH triggers ovulation.
The stage of gestation after the eighth week after fertilization.
Paired female reproductive organs; the ovaries contain eggs and produce estrogen and progesterone.
A hormone secreted by the anterior pituitary. In females, FSH triggers eggs to mature at the start of each monthly cycle.
The shedding of the uterine lining (the endometrium) that occurs when an embryo does not implant.
A structure made of fetal and maternal tissues that helps sustain and support the embryo and fetus.
An early stage of development; an embryo forms when a zygote undergoes cell division.
The release of an egg from an ovary into the oviduct.
A hormone produced by an early embryo that helps maintain the corpus luteum until the placenta develops.
A master control region in the brain that regulates a variety of physiological functions, including hunger, thirst, temperature regulation, and reproduction.
A female sex hormone produced by the ovaries.
The structure in the ovary that remains after ovulation and secretes progesterone.
The part of the ovary where eggs mature.
Table
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Describe the functions and sources of the hormones that regulate the menstrual cycle.

7.

Examine Infographic 30.5 and fill in the following chart. (The first entry is an example.)

Hormone Where is it produced? What does it do?
Gonadotropin-releasing hormone (GnRH) Hypothalamus Stimulates the anterior pituitary to make FSH and LH
FSH

Where is it produced?

What does it do?

LH

Where is it produced?

What does it do?

Estrogen

Where is it produced?

What does it do?

Progesterone

Where is it produced?

What does it do?

Table
Hormone Where is it produced? What does it do?
Gonadotropin-releasing hormone (GnRH) Hypothalamus Stimulates the anterior pituitary to make FSH and LH
FSH Anterior pituitary Triggers eggs to mature at the beginning of each monthly cycle; triggers follicle to produce estrogen
LH Anterior pituitary A spike of LH causes ovulation.
Estrogen Ovary (mostly produced by the follicle but some by the corpus luteum); during pregnancy the placenta produces some estrogen. Triggers pituitary to release LH. Helps thicken the endometrium. Absence of estrogen causes the endometrium to break down and slough off.
Progesterone Ovary (corpus luteum); during pregnancy, the placenta produces progesterone. Helps thicken the endometrium. Continuing production of progesterone helps maintain pregnancy by supporting the endometrium. Absence of progesterone causes the endometrium to break down and slough off.
Table

Explain how the ovaries, hormone levels, and endometrium thickness change throughout the menstrual cycle.

8.

For each step in the menstrual cycle, describe what happens to estrogen levels, progesterone levels, and the endometrium.

Time Ovary, follicle Estrogen levels Progesterone levels Endometrium
Days 1-14 FSH causes a follicle to form and an egg to develop inside it.

Estrogen levels:

Progesterone levels:

Endometrium:

Days 14-24 LH causes release of egg, prompts follicle to become a corpus luteum

Estrogen levels:

Progesterone levels:

Endometrium:

Days 24-28 If a fertilized embryo does not implant in the uterus, the corpus luteum degenerates.

Estrogen levels:

Progesterone levels:

Endometrium:

Table
Time Ovary, follicle Estrogen levels Progesterone levels Endometrium
Days 1-14 FSH causes a follicle to form and an egg to develop inside it. Rise; peak at day 14 Slight rise toward day 14 Begins to thicken
Days 14-24 LH causes release of egg, prompts follicle to become a corpus luteum Declines; slight rise around day 24 Rise; begin to decline around day 24 Continues to thicken
Days 24-28 If a fertilized embryo does not implant in the uterus, the corpus luteum degenerates. Slight rise and then decline Decline At day 24 begins to slough off
Table

Describe the timeline of events leading from ovulation to implantation of an embryo.

13.

What has to occur for an egg to become a zygote? When does this happen?

The egg becomes a zygote when a sperm fuses with the egg cell. This happens at day 0; it is the beginning of pregnancy.

Explain how hormones regulate pregnancy.

16.

Fill in the table with information on the hormones that support pregnancy. The location of hormone production may change, and you should note all the sources.

Hormone Where is it produced? How does it support pregnancy?
Estrogen

Where is it produced?

How does it support pregnancy?

Progesterone

Where is it produced?

How does it support pregnancy?

HCG

Where is it produced?

How does it support pregnancy?

Table
Hormone Where is it produced? How does it support pregnancy?
Estrogen Ovary (mostly by the follicle but some by the corpus luteum)
Placenta
Triggers pituitary to release LH; helps thicken the endometrium
Progesterone Ovary (corpus luteum)
Placenta
Helps thicken the endometrium; continuing production helps maintain pregnancy by supporting the endometrium.
HCG Embryo Maintains corpus luteum, stimulates it to continue to produce progesterone and estrogen until the placenta can take over production.
Table

Predict how hormone levels could be artificially modified to prevent pregnancy.

Birth control pills and other hormone-based contraceptives contain estrogen, progesterone, or both. Refer to Infographics 30.5 and 30.6 to answer these questions.

17.

How would administering progesterone and estrogen prevent pregnancy?

High levels of progesterone inhibit the hypothalamus from signaling the anterior pituitary to secrete FSH and LH. High levels of estrogen prevent the anterior pituitary from releasing FSH. These two hormones also prevent the thickening of the endometrium (a thin endometrium cannot support a growing embryo) and thicken the mucus at the cervix, adding a physical barrier to sperm.

Review Questions

18.

Menstruation occurs when:

A.
B.
C.
D.
E.

2
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Driving Question 3

What are the different types of assisted reproduction, and how do they work?

Why should you care?

Infertility is a distressing issue for many couples, and diagnosing its source is complicated by the many causes of infertility. Although hopefully you will never have to face infertility, understanding its causes will teach you a great deal about your reproductive health in general.

In vitro fertilization (IVF) and intrauterine insemination (IUI) are the two main forms of assisted reproduction. Both methods have a high failure rate, but the chance of multiple births in successful procedures is much higher than the natural rate. Understanding how the procedures work will help you form informed opinions of ethical issues associated with assisted reproduction technologies.

What should you know?

To fully answer this Driving Question, you should be able to:

  1. Describe the causes of infertility in women.
  2. Describe the causes of infertility in men.
  3. Explain the steps of IVF.
  4. Compare and contrast natural fertilization with IVF.
  5. Compare and contrast IUI with IVF.
  6. Explain how IUI and IVF can both lead to multiple births.

Infographic Focus

The Infographics most pertinent to the Driving Question are 30.4, 30.8, and 30.9.

Test Your Vocabulary

Choose the correct term for each of the following definitions:

Term Definition
A form of assisted reproduction in which sperm are injected directly into a woman’s uterus.
A form of assisted reproduction in which eggs and sperm are brought together outside the body and the resulting embryos are inserted into a woman’s uterus.
Table
Correct.
Incorrect.

Describe the various causes of infertility in women.

22.

The following are some of the most common causes of infertility in women:

  • Hormonal imbalances
  • Cancer
  • Genetic problems
  • Undeveloped ovarian tissue
  • Endometriosis
  • Polyps or fibroids
  • Nonreceptive fluids
  • Scarring
  • Infection

Some of these causes lead to infertility through a variety of pathways: for example, one type of cancer may cause infertility through hormonal imbalance, while another causes infertility from blockages.

Come up with an organizing scheme for the different causes and decide on categories to group them in. Conditions causing blockage could be one category, but try to come up with two to four groups for the causes.

In the box, make columns for your categories. Write in the name of each category at the top of the column and list the causes with any notes you want to include about them.

Category:

Category:

Category:

Category:

Fill in:

Fill in:

Fill in:

Fill in:

Table
Causes
Blockages
Hormonal
Imbalances
Hostile Environment
for Sperm
Nonfunctioning
Organs
Cancer
Endometriosis
Scarring
Genetic Problems
Polyps, fibroids
Infections
Cancer
Undeveloped ovarian tissue
Endometriosis
Genetic problems
Polyps, fibroids
Nonreceptive fluids
Infection
Hormonal imbalances
Undeveloped ovarian tissue
Cancer
Endometriosis
Scarring
Genetic problems
Table

Describe the various causes of infertility in men.

23.

The following are some of the most common causes of infertility in men:

  • Hormonal imbalances
  • Cancer
  • Genetic problems
  • Sperm abnormalities
  • Prostatitis
  • Testicular varicose veins
  • Erectile dysfunction
  • Scarring
  • Infection

As with the previous question, some of these causes lead to infertility through a variety of pathways.

Come up with a categorizing scheme for the different causes and decide on categories to group them in. Try to come up with two to four groups for the causes.

In the box make columns for your categories. Write in the name of each category at the top of the column and list the causes with any notes you want to include about them.

Category:

Category:

Category:

Category:

Fill in:

Fill in:

Fill in:

Fill in:

Table
Causes
Blockages
Hormonal
Imbalances
Erectile
Dysfunction
Sperm
Abnormalities
Cancer
Testicular varicose veins
Scarring
Genetic Problems
Prostatitis
Infection
Cancer
Scarring
Genetic problems
Prostatitis
Infection
Cancer
Scarring
Hormonal imbalances
Hormonal imbalances
Testicular varicose veins
Cancer
Genetic problems
Table

Explain the steps of IVF.

24.

What is the first step in IVF, removing eggs from the ovaries, fertility drug treatment, or fertilization?

fertility drug treatment

Compare and contrast natural fertilization with IVF.

28.

Examine Infographics 30.3 and 30.4 in your text to fill in the chart comparing natural fertilization and IVF.

Natural Fertilization IVF
Typical number of eggs released
Where sperm fertilize egg
Number of embryos reaching uterus
Table
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Compare and contrast IUI with IVF.

29.

What is IUI?

IUI, or artificial insemination, occurs when sperm are directly injected into the uterus.

Explain how IUI and IVF can both lead to multiple births.

31.

Why is the chance of multiple births much higher with IVF than with natural fertilization?

The chance of multiple births is much higher with IVF because multiple embryos are inserted into the mother’s uterus. There is a greater likelihood that two or more of these embryos will implant in the uterine wall and develop into a fetus. In natural fertilization, there is typically only one embryo.

Review Questions

35.

Which of the following is NOT a known cause of female infertility?

A.
B.
C.
D.

2
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