Chapter 51
Reproductive System
Table of Contents
Section 1 Male Reproductive System
Section 2 Female Reproductive System
Section 3 Gestation
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Chapter 51
Section 1 Male Reproductive
System
Objectives
• Identify the major structures of the male reproductive
system.
• Describe the function of each structure of the male
reproductive system.
• Relate the structure of a human sperm cell to its
function.
• Trace the path that sperm follow in leaving the body.
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Chapter 51 Male Reproductive Structures
• The male reproductive system
contains two testes.
– The testes are the gameteproducing organs of the male
reproductive system.
– **Testes contain seminiferous
tubules
– **Scrotum houses the testis, & is
lower in temperature than in the
abdomen
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Chapter 51
Section 1 Male Reproductive
System
Male Reproductive Structures, continued
• Each testis is made up of the
epididymis and the seminiferous
tubules.
– The epididymis is a long, coiled
tubule that is closely attached to
each testis.
– **Epididymis is the site of sperm
maturation
– The seminiferous tubules are
tightly coiled tubules where sperm
form through meiosis.
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Chapter 51
Section 1 Male Reproductive
System
Formation of Sperm
• At puberty, sperm form through
meiosis.
• Sperm contain a **head, a midpiece,
and a tail.
– The **head contains the enzymes
and chromosomes (DNA) that will
be delivered to the egg.
– The midpiece’s mitochondria power
the movement of the tail.
– **Flagellum is the sperms tail
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Chapter 51
Section 1 Male Reproductive
System
Formation of Sperm, continued
• Path of Sperm Through the Male Body
– The path of the sperm through the body begins
as the sperm move from the seminiferous
tubules to the epididymis.
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Chapter 51
Section 1 Male Reproductive
System
Formation of Sperm, continued
• Path of Sperm Through the Male Body, continued
– From the epididymis, sperm move into the vas
deferens.
• The **vas deferens is a duct that extends from
the epididymis to the urethra. This duct is made
of smooth muscle and helps sperm exit the body.
– From the vas deferens, sperm move to the
urethra.
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Chapter 51
Section 1 Male Reproductive
System
Formation of Sperm, continued
• Path of Sperm Through the Male Body, continued
– Once in the urethra, the sperm will mix with other fluids
produced by the seminal vesicles, the prostate gland, and
the bulbourethral glands.
• The seminal vesicles lie between the bladder and the
rectum and produce a fluid that sperm use for energy.
• The **prostate gland is located just below the bladder
and produces a fluid that neutralizes the acids in the
female reproductive system.
• The **bulbourethral glands produce a fluid that
neutralizes any acidic urine left in the urethra.
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Chapter 51
Section 1 Male Reproductive
System
Male Reproductive System
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Chapter 51
Section 1 Male Reproductive
System
Formation of Sperm, continued
• Delivery of Sperm
– Fluids that are excreted from glands within the penis are mixed
with the sperm to produce semen.
– **The secretions of the prostate gland contribute to the
production of sperm
– After passing through the urethra, the semen will exit the body
through the penis.
• The penis is the organ that deposits sperm in the female
reproductive system.
– Ejaculation is the process in which semen is forcefully expelled
from the penis by contractions of the smooth muscles that line
the urethra.
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Chapter 51
Section 2 Female Reproductive
System
Objectives
• Identify the major structures of the female
reproductive system.
• Describe the function of each structure of the female
reproductive system.
• Describe how eggs are produced.
• Summarize the stages of the ovarian cycle.
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Chapter 51
Section 2 Female Reproductive
System
Female Reproductive Structures
• The female reproductive system contains two
ovaries, two fallopian tubes, and a uterus.
• **The ovary secrets estrogen in response to
LH stimulation
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Chapter 51
Section 2 Female Reproductive
System
Female Reproductive Structures, continued
• The ovaries are the gamete-producing organs of the
female reproductive system.
• The fallopian tubes, also called the uterine tubes, are
made of smooth muscle and join the ovary to the uterus.
• **Fallopian tube is the site of fertilization
• The uterus is a hollow, muscular organ about the size of
a small fist and is the place where the fertilized egg will
develop.
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Chapter 51
Section 2 Female Reproductive
System
Female Reproductive System
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Chapter 51
Section 2 Female Reproductive
System
Female Reproductive Structures, continued
• The lower entrance of the uterus is the cervix, which leads to
the female reproductive opening called the vagina.
– The **vagina is a muscular tube that leads to the outside of
the body. The vagina receives ejaculated sperm from the
penis, and it is also the channel through which a baby
passes during childbirth.
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Chapter 51
Section 2 Female Reproductive
System
Formation of Eggs
• Unlike males, a female is born with all the eggs she will
ever produce.
• These immature eggs will be stimulated to mature starting
at puberty. A hormone will stimulate a batch of eggs to
continue to mature about every 28 days.
• However, an egg will not complete maturation until
fertilized by a sperm.
• If fertilized, the mature egg, or ovum, will continue
development as it travels through the fallopian tube.
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Chapter 51
Section 2 Female Reproductive
System
Preparation for Pregnancy
• The female reproductive
system will prepare and
release an ovum each month
in a process called the ovarian
cycle, which is controlled by
the endocrine system.
• The ovarian cycle has 3
phases: the follicular phase,
ovulation, and the luteal phase.
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Chapter 51
Section 2 Female Reproductive
System
Preparation for Pregnancy, continued
• Follicular Phase
– The follicular phase is when the immature egg
will complete its first meiotic division. This phase
begins because it is stimulated by the follicle
stimulating hormone (FSH).
• FSH will stimulate the egg to mature by
stimulating the **follicle, or layer of cells that
surrounds an immature egg, to divide.
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Chapter 51
Section 2 Female Reproductive
System
Preparation for Pregnancy, continued
• Ovulation
– Ovulation is when an egg is released by the
follicle.
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Chapter 51
Section 2 Female Reproductive
System
Preparation for Pregnancy, continued
• **Luteal Phase
– During the luteal phase,
the cells of the ruptured
follicle grow larger and
create a new structure
called a corpus luteum.
1. If the egg is not fertilized,
this phase will end with
menstruation
2. Uterine lining sloughs off
3. FSH levels can begin to
rise
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Chapter 51
Section 2 Female Reproductive
System
Preparation for Pregnancy, continued
• Menstruation
– Menstruation is when the lining of the uterus and
blood from ruptured blood vessels are discharged
through the vagina.
• This process can last about 5 to 7 days until a
woman reaches menopause.
– Menopause is when most of a woman’s follicles have
either matured and ruptured or degenerated. Thus,
menstruation ceases.
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Chapter 51
Section 3 Gestation
Objectives
• Sequence the events of fertilization, cleavage, and
implantation.
• Describe the three stages of pregnancy.
• Summarize the development of an embryo during
pregnancy.
• Discuss the effects of unnecessary drug use on
development.
• Describe the changes in a mother’s body during
birth.
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Chapter 51
Section 3 Gestation
Fertilization
• If sperm are ejaculated into a female within 48 to 72
hours of ovulation, the chances of those sperm
finding and fertilizing and egg are likely.
• Once any sperm encounters an egg, it will try to
penetrate its outer layers, but usually only one
sperm is successful in fertilizing the egg.
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Chapter 51
Section 3 Gestation
Fertilization, continued
• When fertilization occurs, the egg and sperm fuse to
form a zygote.
– A zygote is the diploid cell that results when the
egg and sperm fuse together.
– **Both egg and sperm have the haploid (1n)
number of chromosomes
• The period of development from fertilization of the
egg through the next **nine months is known as
gestation.
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Chapter 51
Section 3 Gestation
Early Zygote Development
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Chapter 51
Section 3 Gestation
Fertilization, continued
• Cleavage and Implantation
– Once the egg is fertilized, the zygote will begin a
series of mitotic divisions known as cleavage.
– **Transformation of a zygote to a blastocyst
requires cleavage
– **The male reproductive organ that has similar
functions to those of an ovary is the testis
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Chapter 51
Section 3 Gestation
Fertilization, continued
• Cleavage and Implantation
– The morula has become a blastocyst by the
time it reaches the uterus.
– Once at the uterus, the blastocyst releases an
enzyme that allows it to burrow into the
thickened walls of the uterine lining. This
process is called implantation.
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Chapter 51
Section 3 Gestation
Pregnancy
• The **nine-month period of growth and development
that a blastocyst undergoes is called gestation or
pregnancy.
• Pregnancy is divided into three equal periods called
trimesters, and each trimester is signaled by specific
events.
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Chapter 51
Section 3 Gestation
Pregnancy, continued
• First Trimester
– During the first eight weeks of pregnancy, the
developing human is called an embryo.
– The embryo during this phase looks much like all
other developing animal embryos, but it will soon
reorganize into the primary germ layers: the
endoderm, mesoderm, and ectoderm.
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Chapter 51
Section 3 Gestation
Pregnancy, continued
• First Trimester
– During the first trimester, four membranes form
that will be essential in the development of the
embryo.
– One membrane is called the amnion and forms
the amniotic sac, which keeps the embryo moist
and protected by surrounding the developing
embryo.
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Chapter 51
Section 3 Gestation
Pregnancy, continued
• **First Trimester
– The second membrane is called the yolk sac, which is where
the first blood cells will originate from.
– The third membrane is called the allantois chorion.
– The fourth membrane is called the chorion, which surrounds
all other membranes and forms the chorionic villi.
• The chorionic villi are finger like projections that will
attach and extend into the uterine lining.
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Chapter 51
Section 3 Gestation
Pregnancy, continued
• First Trimester
– The chorionic villi and part of the uterine lining will form the
placenta. The **placenta is the structure through which the
mother nourishes the embryo (passes nutrients from mother
to fetus)
– The placenta connects the mother to the embryo by way of
the umbilical cord. The umbilical cord allows substances to
exchange between mother and embryo by way of diffusion.
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Chapter 51
Section 3 Gestation
Pregnancy, continued
• First Trimester
– From eight weeks until birth, the developing child
is called a fetus.
– At the end of the first trimester, all of the organs of
the fetus have begun to form.
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Chapter 51
Section 3 Gestation
Pregnancy, continued
• Second Trimester
– During the second trimester,
the heartbeat of the fetus can
be heard, its skeleton begins
to form, and it begins to
develop body fat.
– The baby has a layer of soft
hair called lanugo growing
over its skin.
– The baby begins to move,
sleep, and wake.
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Chapter 51
Section 3 Gestation
Pregnancy, continued
• Third Trimester
– During the third trimester, the baby undergoes
changes that will enable it to live outside the
mother.
– It also develops fat deposits under its skin to
insulate its body.
• These fat deposits also make the fetus look
more rounded and less wrinkled.
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Chapter 51
Section 3 Gestation
Birth
• In reaction to hormones
produced by both the
fetus and the mother,
childbirth is initiated.
• During childbirth, the
smooth muscles of the
uterus begin to contract
and the muscles in the
vagina and cervix relax
and enlarge, which allow
the fetus to pass through.
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Chapter 51
Section 3 Gestation
Birth, continued
• The process of muscle contractions and other related
events that lead up to childbirth are called labor.
• **Labor is the process in which the fetus leaves the
mother’s body
• After the fetus has been pushed through the vagina,
contractions of the uterus help the mother expel the
**placenta, amnion, and uterine lining. This group of
membranes is called the afterbirth.
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Chapter 51
Standardized Test Prep
Multiple Choice
1. Which of the following is the correct pathway for
sperm as it exits the body?
A. the testes to the penis to the epididymis
B. the urethra to the vas deferens to the testes
C. the epididymis to the vas deferens to the urethra
D. the testes to the vas deferens to the epididymis
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Chapter 51
Standardized Test Prep
Multiple Choice, continued
1. Which of the following is the correct pathway for
sperm as it exits the body?
A. the testes to the penis to the epididymis
B. the urethra to the vas deferens to the testes
C. the epididymis to the vas deferens to the urethra
D. the testes to the vas deferens to the epididymis
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Standardized Test Prep
Multiple Choice, continued
2. Which of the following is true about follicle-stimulating
hormone?
F. It is secreted by the follicle.
G. It is secreted by the pituitary gland.
H. It promotes contractions of the uterus.
J. It stimulates the development of the placenta.
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Chapter 51
Standardized Test Prep
Multiple Choice, continued
2. Which of the following is true about follicle-stimulating
hormone?
F. It is secreted by the follicle.
G. It is secreted by the pituitary gland.
H. It promotes contractions of the uterus.
J. It stimulates the development of the placenta.
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Chapter 51
Standardized Test Prep
Multiple Choice, continued
3. Which of the following help form the placenta and
umbilical cord?
A. the amnion and chorion
B. the amnion and yolk sac
C. the chorion and yolk sac
D. the chorion and allantois
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Standardized Test Prep
Multiple Choice, continued
3. Which of the following help form the placenta and
umbilical cord?
A. the amnion and chorion
B. the amnion and yolk sac
C. the chorion and yolk sac
D. the chorion and allantois
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Standardized Test Prep
Multiple Choice, continued
4. By the end of the first trimester, which of following
has occurred in the fetus?
F. The fetus has a full head of hair.
G. The fetus uses its lungs to breathe.
H. The brain of the fetus is fully developed.
J. All of the organs of the fetus have begun to form.
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Standardized Test Prep
Multiple Choice, continued
4. By the end of the first trimester, which of following
has occurred in the fetus?
F. The fetus has a full head of hair.
G. The fetus uses its lungs to breathe.
H. The brain of the fetus is fully developed.
J. All of the organs of the fetus have begun to form.
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Standardized Test Prep
Multiple Choice, continued
Use the figure below to answer questions 5–6. The
figure shows the image of a sperm cell.
5. Where are the enzymes that help the sperm
penetrate the ovum found?
A. in the head
B. in the nucleus
C. in the midpiece
D. in the flagellum
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Chapter 51
Standardized Test Prep
Multiple Choice, continued
Use the figure below to answer questions 5–6. The
figure shows the image of a sperm cell.
5. Where are the enzymes that help the sperm
penetrate the ovum found?
A. in the head
B. in the nucleus
C. in the midpiece
D. in the flagellum
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Chapter 51
Standardized Test Prep
Multiple Choice, continued
Use the figure below to answer questions 5–6. The
figure shows the image of a sperm cell.
6. Where are the mitochondria that supply the energy
that sperm need for movement?
F. in the head
G. in the nucleus
H. in the midpiece
J. in the flagellum
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Chapter 51
Standardized Test Prep
Multiple Choice, continued
Use the figure below to answer questions 5–6. The
figure shows the image of a sperm cell.
6. Where are the mitochondria that supply the energy
that sperm need for movement?
F. in the head
G. in the nucleus
H. in the midpiece
J. in the flagellum
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Multiple Choice, continued
7. testis : ovary :: vas deferens :
A. sperm
B. urethra
C. fallopian tube
D. prostate gland
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Multiple Choice, continued
7. testis : ovary :: vas deferens :
A. sperm
B. urethra
C. fallopian tube
D. prostate gland
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Multiple Choice, continued
Use the figure below to answer question 8. The
figure shows the image of a an ovary.
8. What event is illustrated by this figure?
F. ovulation
G. ejaculation
H. fertilization
J. menstruation
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Multiple Choice, continued
Use the figure below to answer question 8. The
figure shows the image of a an ovary.
8. What event is illustrated by this figure?
F. ovulation
G. ejaculation
H. fertilization
J. menstruation
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Chapter 51
Standardized Test Prep
Short Response
Sperm are able to survive for around 48 hours in a
female even though they have very little
cytoplasm to provide nutrients. Explain why you
think sperm can survive with few nutrients.
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Standardized Test Prep
Short Response, continued
Sperm are able to survive for around 48 hours in a
female even though they have very little
cytoplasm to provide nutrients. Explain why you
think sperm can survive with few nutrients.
Answer: The seminal fluids secreted by exocrine
glands nourish and protect the sperm.
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Chapter 51
Standardized Test Prep
Extended Response
Base your answers to parts A & B on the information below.
During the 1950s, a number of women were prescribed
thalidomide, a drug to relieve morning sickness. These
women gave birth to babies with serious limb defects.
Scientists later discovered that thalidomide caused limb
defects in fetuses.
Part A Do you think it is safe for a woman to take thalidomide
during her first and second trimesters of pregnancy? Explain
your answer.
Part B Do you think it is safe for a woman to take thalidomide
during the third trimester of her pregnancy? Explain your
answer.
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Extended Response, continued
Answer:
Part A It is not safe because the drug can cause limb
deformations and the fetus’s limbs are forming
during these trimesters.
Part B It is probably safer for the woman to take this
drug during this trimester than the first and second
trimester because the drug’s only known side effect
is limb deformation and the fetus’s limbs would have
already formed by the third trimester. However,
women should avoid taking any drugs during
pregnancy without consulting a doctor.
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