Download 34.3 The Reproductive System

Name
Class
Date
34.3 The Reproductive System
Lesson Objectives
Describe the effects the sex hormones have on development.
Name and discuss the structures of the male reproductive system.
Name and discuss the structures of the female reproductive system.
Describe some of the most common sexually transmitted diseases.
Lesson Summary
Sexual Development Hormones released by the ovaries and testes cause sexual
development during puberty, a period of rapid growth and sexual maturation that usually
starts between the ages of 9 and 15. At the end of puberty, the male and female reproductive
organs are fully developed and become fully functional.
The Male Reproductive System The main role of the male reproductive system is to
make and deliver sperm.
▶ The testes are the main organs of the male system. Two testes are held in an external sac
called the scrotum. The testes make sperm in tiny tubes called seminiferous tubules. The
sperm mature and are stored in an epididymis. A tube called a vas deferens carries sperm
from each testis to the urethra within the penis.
▶ Along the way, secretions of several glands form a nutrient-rich fluid called seminal
fluid. The combination of sperm and seminal fluids is called semen. Semen leaves the
body through the urethra. Contractions eject semen from the penis in a process called
ejaculation.
▶ A mature sperm cell consists of a head that contains the nucleus, a midpiece that is packed
with mitochondria, and a flagellum that propels the sperm.
The Female Reproductive System The main roles of the female reproductive system are
to make eggs and prepare the female body to nourish an embryo.
▶ The ovary is the main organ of the female system. Each ovary has thousands of follicles,
which are clusters of cells that surround an egg. A mature egg moves through the
Fallopian tube to the uterus, which is connected to the outside of the body by the vagina.
▶ Beginning in puberty, the female body goes through a menstrual cycle, a series of events
that prepares the body to care for a fertilized egg. The menstrual cycle has four phases:
• Follicular phase: An egg matures in its follicle.
• Ovulation: The mature egg is released from the ovary.
• Luteal phase: The follicle develops into a structure called the corpus luteum.
• Menstruation: The lining of the uterus falls away and leaves the body through the
vagina if the egg is not fertilized.
Sexually Transmitted Diseases A disease spread during sexual contact is called a
sexually transmitted disease (STD). Bacteria and viruses can cause STDs. Chlamydia,
syphilis, gonorrhea, and AIDS are STDs.
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536
Name
Class
Date
Sexual Development
For Questions 1–3, write the letter of the correct answer on the line at the left.
B
1. Male and female embryos are nearly identical until the
A. second week of development.
C. third month of development.
B. seventh week of development.
D. fifth month of development.
A
2. Which hormone, when produced in an embryo, triggers a male pattern of
development?
A. testosterone
C. estrogen
B. progesterone
D. adrenalin
D
3. The period of human development that includes rapid growth and sexual
maturation is called
A. adolescence.
C. maturity.
B. childhood.
D. puberty.
The Male Reproductive System
For Questions 4–8, match each structure of the male reproductive system with its description.
Description
Structure
C
4. epididymis
A. External sac that holds male gonads
A
5. scrotum
B. The primary male reproductive organ
D
6. seminiferous tubule
C. Structure in which sperm mature
B
7. testis
D. Structure in which meiosis occurs
E
8. vas deferens
E. The tube through which sperm travel to the
urethra
For Questions 9–12, complete each statement by writing the correct word or words.
prostate
9. The seminal vesicles,
gland, and bulbourethral gland produce a
seminal
nutrient-rich fluid called
fluid.
10. Sperm mixed with the seminal fluid is called
11. Signals from the
autonomic
semen
.
nervous system cause sperm to be ejaculated.
midpiece
of a sperm cell contain mitochondria that supply energy to the
flagellum
, which propels the sperm forward.
12. The
The Female Reproductive System
For Questions 13–16, complete each statement by writing the correct word or words.
13. The primary reproductive organs of females are the
14. The function of a(n)
15. Only about
mature ovum.
400
follicle
ovaries
.
is to help an egg mature.
of the 400,000 eggs a female is born with develop into a
16. The structure of the female reproductive system in which the embryo develops is called
uterus
the
.
Lesson 34.3 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
537
Name
Class
Date
For Questions 17–20, match each phase of the menstrual cycle with the correct event.
Phase
Event
C
17. Follicular phase
A. An unfertilized egg leaves the body.
D
18. Ovulation
B. The egg travels through a Fallopian tube.
B
19. Luteal phase
C. An egg within a follicle develops.
A
20. Menstruation
D. An egg is released from an ovary.
21. Complete the concept map to explain what the outcomes of a menstrual cycle can be.
Mature ovum
enters the
Fallopian tube
No sperm are in female tract
Sperm are present in female tract
Menstruation
will occur
Fertilization
could result
Sexually Transmitted Diseases
For Questions 22–24, write True if the statement is true. If the statement is false, change the
underlined word or words to make the statement true.
Chlamydia
22. AIDS is the most common bacterial STD.
True
23. Chlamydia damages the reproductive tract and can cause infertility.
True
24. Hepatitis B and genital herpes are viral STDs.
25. How is the menstrual cycle an example of the body’s use of negative feedback?
SAMPLE ANSWER:
The female body uses negative feedback during the menstrual cycle
to maintain its readiness for reproduction. The presence of higher levels of hormones
such as estrogens and progesterone causes their production to slow. In turn, the
dropping levels of the hormones stimulate their increased production.
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538
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Class
Date
34.4 Fertilization and Development
Lesson Objectives
Describe fertilization and the early stages of development.
Identify the major events of later stages of development.
Lesson Summary
Fertilization and Early Development Fertilization is the joining of a sperm and an egg.
Following fertilization, a series of events called development begins.
▶ A fertilized egg is called a zygote. The zygote divides and undergoes repeated rounds of
mitosis and develops into a hollow ball of cells called a blastocyst.
▶ About a week after fertilization, the blastocyst attaches to the wall of the uterus in the
process of implantation. At the same time, cells of the blastocyst start to specialize
through differentiation. Some cells migrate to form two cell layers—the ectoderm and the
endoderm.
▶ A third layer of cells is produced by a process called gastrulation, in which cells from the
ectoderm migrate to form the mesoderm. The three layers eventually develop into the
different organs of the embryo.
▶ During neurulation, the notochord and the neural tube form. The neural tube eventually
develops into the brain and spinal cord.
▶ As the embryo develops, membranes for protection and nourishment also form. Part
of one membrane combines with the uterine lining to form the placenta. Mother and
embryo/fetus exchange gases, food, and waste products across the placenta. The umbilical
cord connects the embryo/fetus to the placenta.
▶ After eight weeks of development, the embryo is called a fetus. By the end of three
months, most organs are fully formed.
Later Development Another six months of development occurs before birth.
▶ During months 4–6, the fetus’s tissues become specialized and organs such as the heart
begin to function.
▶ During months 7–9, the fetus’s organ systems mature as the fetus grows in size and mass.
The lungs and the central nervous system complete their development.
▶ Childbirth occurs about nine months after fertilization, when hormones cause
contractions in the mother’s uterus. The contractions first push the baby out through the
vagina. Then, more contractions expel the placenta and amniotic sac from the uterus.
Shortly after birth, the mother’s breast tissue begins to produce milk that contains
everything the baby needs for the first months of life.
▶ The placenta is a barrier to many harmful agents, but some are able to pass through it,
such as viruses that cause AIDS and German measles. Alcohol, drugs, and smoking also
have negative effects on embryos and fetuses. Prenatal care and advancements in medical
technology have lowered the infant mortality rate.
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539
Name
Class
Date
Fertilization and Early Development
For Questions 1–4, complete each statement by writing the correct word or words.
fertilization
1. The fusion of a sperm with an egg is called
2. During implantation, the
blastocyst
.
embeds itself into the lining of the uterus.
3. Embryonic structures called chorionic villi combine with the uterine lining to form
placenta
the
.
4. The embryo is surrounded by fluid called the
amniotic
fluid.
5. Complete the table by identifying events and structures of early development.
Event or Structure
What It Is
Fertilization
The process in which sperm joins an egg
Ectoderm
The layer of cells that develops into the skin and nervous system
Gastrulation
Process that results in the formation of three cell layers
Neurulation
Early stage in the development of the nervous system
Endoderm
The innermost layer of cells in the early embryo that forms
the lining of some organs
Amniotic sac
Fluid-filled structure that cushions and protects the embryo
Placenta
Embryo’s organ of respiration, nourishment, and excretion
Mesoderm
Forms internal structures such as bones and muscles
Umbilical cord
Structure that connects the fetus to the placenta
Later Development
6. What major changes occur in a developing fetus during months 4–6 of pregnancy?
The tissues of the fetus become more complex and specialized, and they begin to function. The heart becomes larger. Bone replaces cartilage.
7. What major changes occur in a developing fetus during months 7–9 of pregnancy?
The organ systems of the fetus mature, and the organs undergo changes that prepare
them for life outside of the uterus. The fetus doubles in size. It begins to regulate its
own body temperature. The nervous system and lungs complete development.
Lesson 34.4 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
540
Name
Class
Date
For Questions 8–13, write the letter of the correct answer on the line at the left.
B
8. The contractions of labor before childbirth are triggered by
A. the amniotic fluid.
B. the hormone oxytocin.
C. the umbilical cord.
D. the uterine wall.
C
9. The term “afterbirth” refers to the
A. amnion and the chorion.
B. clamping of the umbilical cord.
C. placenta and amniotic sac.
D. production of milk for the baby.
B
10. What is a belly button?
A. a structure with an unknown purpose
B. a scar left from the umbilical cord
C. remains of the notochord
D. the point where implantation occurred
D
11. Which hormone causes the mother’s breast tissue to begin producing milk?
A. estrogen
B. oxytocin
C. progesterone
D. prolactin
D
12. Using alcohol during pregnancy can harm a developing embryo, especially its
A. reproductive system.
B. circulatory system.
C. endocrine system.
D. nervous system.
A
13. Which public health measure has decreased the incidence of spina bifida?
A. the addition of folic acid to grain products
B. the development of new types of baby formula
C. the programs aimed at reducing smoking and alcohol use
D. the use of a vaccine that prevents German measles
14. Women with Type 1 diabetes may face challenges controlling blood sugar levels during
pregnacy. Early in pregnancy, the developing fetus removes glucose from the mother’s
blood at a great rate. Would this raise or lower her need for insulin?
This would lower her need for insulin. By removing a lot of glucose from her blood,
the fetus would help keep her blood glucose levels at an appropriate level.
Lesson 34.4 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
541
Name
Class
Date
Chapter Vocabulary Review
On the lines provided, label the structures of the
male reproductive system that correspond to the
numbers in the diagram.
1.
1. Vas deferens
2.
Epididymis
3.
Testis
2.
3.
For Questions 4–10, match the term with its definition.
Term
Definition
F
4. endocrine gland
A. Mixture of sperm and seminal fluids
G
5. exocrine gland
B. Attachment of the blastocyst to the uterine wall
E
6. gastrulation
D
7. hormone
C. Discharge of uterine tissue and blood from the
vagina
B
8. implantation
C
9. menstruation
A
10. semen
D. Chemical made in one part of the body that travels
in the bloodstream to other parts
E. The process that produces the three cell layers of
the embryo
F. Type of gland that releases its chemicals directly
into the bloodstream
G. Type of gland that releases its chemicals
out of the body
For Questions 11–18, complete each statement by writing the correct word or words.
11. After eight weeks of development, an embryo is called a
fetus
.
12. The gland that produces hormones that regulate the secretions of other glands is
the
pituitary
gland.
13. Cells with receptors for a particular hormone are called
14. A fertilized egg is called a
Prostaglandins
15.
zygote
target
cells.
.
are also known as “local hormones.”
16. Oxygen and nutrients diffuse from the mother’s blood to the embryo’s blood through
the
placenta
.
17. The early stages of the brain and spinal cord form during
neurulation .
18. Sperm are produced in ducts called the seminiferous tubules.
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In the Chapter Mystery, you learned about
what happens when the body is not given
everything it needs. Nonessential life
processes, such as menstruation, may stop.
In addition, the body may begin to take
nutrients from organs and tissues.
OUT OF STRIDE
Learning
Giving Your Body What It Needs
There are many diseases associated with undernutrition. In this country, most undernutrition
diseases and disorders are associated with psychological issues rather than a lack of available
nutrients. One of the most common of these diseases is anorexia nervosa. This is part of the
FAQs page on a Web site about anorexia nervosa.
FAQS About Anorexia
Q: What is anorexia nervosa?
A: Anorexia nervosa is a medical condition that affects how a person thinks about food and about his
or her own body.
Return to Top
Q: Does anorexia affect only girls and women?
A: It’s true that 90–95% of anorexics are female, but that means that 5–10% are boys and men.
Return to Top
Q: What causes anorexia?
A: We don’t know. We don’t even know if there is one cause or many. But there are risk factors.
Return to Top
Q: What are the risk factors?
A: The first is culture. Anorexia almost exclusively affects people who grew up in or moved to
Western cultures where they were exposed to images of the “ideal” body type for their sex. For
example, Western media is full of images of flawless, thin women.
Having a relative with anorexia makes it more likely a person will develop it. It’s possible that
personality traits and genetic factors are involved as well.
Return to Top
Q: What effect does anorexia have on the human body?
A: The symptoms of anorexia vary depending on the severity and length of time the person has
suffered from the disease. Anorexia changes the brain chemistry, causing irritability, moodiness,
and difficulty thinking. The hair and nails become brittle. The blood pressure goes down and the
heart rate slows. The skin becomes dry and bruises easily. Bones lose mass and break more easily.
Other symptoms include kidney stones and kidney failure, anemia, yellowing of the skin, and
the growth of fine hairs over the entire body. In women, anorexia stops the menstrual cycle and
increases the possibility of miscarriage and low birth weight.
Return to Top
Continued on next page ▶
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543
Name
Class
Themes
Date
Science and Health Literacy
1. What percentage of anorexics are male?
5–10%
2. What parts of the body are affected by anorexia nervosa?
The brain, hair, nails, heart, skin, bones, kidneys, blood, and in women at least, the
reproductive system
3. What symptoms are described both in this FAQ and in the solution to the Chapter
Mystery?
Stopping of the menstrual cycle and bones losing mass and breaking more easily
4. What do you think some of the treatments for anorexia might be?
SAMPLE ANSWER:
First, the patient would be fed a nutrient-rich diet under supervision.
The patient would then receive psychiatric care in order to treat the underlying causes
of the disease.
5. Suggest some ways in which the incidence of anorexia nervosa in the United States might
be decreased.
SAMPLE ANSWER:
Encourage advertising agencies, magazine publishers, cosmetic and
clothing companies to use models with a wide variety of body types. Have media give
coverage to female athletes, politicians, businesswomen, and other role models that
do not fit the mainstream idea of the ideal feminine form.
Help Wanted: Nutritionist
The skills used in this activity include communication skills, creativity and intellectual
curiosity, interpersonal and collaborative skills, accountability and adaptability, and
social responsibility.
An interest in nutrition could lead to a career as a nutritionist or a dietician. Nutritionists
and dieticians work in hospitals, nursing homes, medical offices, schools, governmental
agencies, and any number of other places. Use library or Internet resources to research
the various job opportunities that involve nutrition. Then write up a help wanted ad that
describes your ideal job.
Compare your ad with those of your classmates.
Students’ ads should describe the job and the qualifications required for the job.
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