Transcript Chapter_19.1.ppt

Lesson 1
The Beginning of the Life Cycle
Did you know that your body is
made of trillions of cells?
Your heart, lungs, skin, bones, and
other body organs all began as a single
cell that is smaller than the period at
the end of this sentence.
Lesson 1
Lesson Objectives
In this lesson, you’ll learn to:
Explain fetal development from conception through pregnancy
and birth.
Recognize how nutrients and other substances are transferred
from a pregnant female to her fetus.
Lesson 1
Conception and Implantation
Fertilization
The entire complex human body begins as one microscopic
cell that is formed by fertilization.
The resulting cell is called a zygote.
Within a day after the zygote forms, it begins dividing as it
travels down the fallopian tube.
Lesson 1
Conception and Implantation
Implantation
By the time it reaches the uterus,
the zygote has divided many times
to form a cluster of cells.
After implantation of the zygote,
the cluster of cells is known as an
embryo.
Click image to view movie.
Lesson 1
Conception and Implantation
Embryo
Click image to view movie.
Lesson 1
Embryonic Growth
Structures Formed During Embryonic Growth
As the embryo grows, its cells continue to divide, forming
three tissue layers that later become various body systems.
During this time, two important structures form outside the
embryo:
1. Amniotic sac
2. Umbilical cord
Lesson 1
Embryonic Growth
Substances Passed to the Embryo
Although the blood supply of the mother and the developing
embryo are kept separate, materials diffuse from one blood
supply to the other through the umbilical cord.
Nutrients and oxygen pass from the mother’s blood to the
embryo, and wastes from the embryo diffuse into the mother’s
blood.
If a pregnant female uses harmful substances, they can cross
the placenta and harm the developing embryo.
Lesson 1
Fetal Development
Trimesters
The time from conception to birth is usually about nine full
months.
These nine months are divided into three 3-month periods
called trimesters.
During the period of growth in the uterus, the fetus develops
in preparation for living outside the mother’s body.
Lesson 1
Fetal Development
First Trimester – 0-14 Weeks
In the first trimester, the fetus develops a human profile. By week
12 the fetus makes crying motions but no sound and may suck its
thumb.
Lesson 1
Fetal Development
Second Trimester – 15-28 Weeks
In the second trimester, the fetus can hear conversations and has
a regular cycle of waking and sleeping. Weight increases rapidly.
Lesson 1
Fetal Development
Third Trimester – 29 Weeks to Birth
In the third trimester, the fetus uses all five senses and begins to
pass water from the bladder.
Lesson 1
Stages of Birth
Changes Experienced During Labor
Many females experience weak, irregular muscular
contractions of the uterus for weeks or even months before
the baby is born.
As the time approaches for the baby to be born, however,
these contractions become regular, stronger, and closer
together.
The stronger contractions induce labor.
Lesson 1
Stages of Birth
Stages of Labor
Stage 1: Dilation
Stage 2: Passage
through birth canal
Stage 3: Afterbirth
Lesson 1
Quick Review
Choose the appropriate option.
Q. The union of a male sperm cell
and a female egg cell is called
_________.
1. zygote
2. implantation
3. fertilization
4. labor
Lesson 1
Quick Review - Answer
A. The union of a male sperm cell and a female egg cell is
called fertilization.
Click Next to attempt another question.
Lesson 1
Quick Review
Choose the appropriate option.
Q. The zygote attaches to the
uterine wall in the process
called _________.
1. labor
2. implantation
3. fertilization
4. cell division
Lesson 1
Quick Review - Answer
A. The zygote attaches to the uterine wall in the process
called implantation.
Click Next to attempt another question.
Lesson 1
Quick Review
Provide a short answer to the question given below.
Q. How is a developing fetus nourished?
Click Next to view the answer.
Lesson 1
Quick Review - Answer
A. Nutrients from the mother pass to the developing fetus
through the blood in the umbilical cord.
Click Next to attempt another question.
Lesson 1
Quick Review
Provide a suitable explanation.
Explain how harmful substances taken in by a pregnant female
can be transferred to a developing fetus. How might fetal
development be affected?
Lesson 1
Quick Review - Answer
A. Correct! The union of a male sperm cell and a female egg cell
is called fertilization.
Click Next to attempt another question.
Lesson 1
Quick Review - Answer
You have answered the question incorrectly. Go back to try
again, or click Next to view the correct answer.
Lesson 1
Quick Review - Answer
A. Correct! The zygote attaches to the uterine wall in the
process called implantation.
Click Next to attempt another question.
Lesson 1
Quick Review - Answer
You have answered the question incorrectly. Go back to try
again, or click Next to view the correct answer.
Lesson 1
Stages of Birth
Stages of Labor
Stage 1: Dilation
Stage 2: Passage
through birth canal
Stage 3: Afterbirth
Lesson 1
Stages of Birth
Stages of Labor
Stage 1: Dilation
Stage 2: Passage
through birth canal
Stage 3: Afterbirth
Lesson 1
Conception and Implantation
Fertilization
The entire complex human body begins as one microscopic
cell that is formed by fertilization.
The resulting cell is called a zygote.
The union of
a male
sperm
cell dividing as it
Within a day after the zygote
forms,
it begins
and a female egg
travels down the fallopian tube.
cell is called
fertilization.
Lesson 1
Conception and Implantation
Implantation
By the time it reaches the uterus,
the zygote has divided many times
to form a cluster of cells.
After implantation of the zygote,
the cluster of cells is known as an
The zygote
embryo.
attaches to the
uterine wall in the
process called
implantation.
Click image to view movie.
Lesson 1
Conception and Implantation
Implantation
By the time it reaches the uterus,
the zygote has divided many times
to form a cluster of cells.
After implantation of the zygote,
the cluster of cells is known as an
embryo.
The cluster of
cells that develop
between the third
and eighth weeks of
pregnancy is called
an embryo.
Click image to view movie.
Lesson 1
Embryonic Growth
Structures Formed During Embryonic Growth
amniotic
As the embryo grows,The
its cells
continue to divide, forming
sacthat
is alater
thin,become
fluid- various body systems.
three tissue layers
filled membrane that
and structures form outside the
During this time,surrounds
two important
protects the
embryo:
developing embryo.
1. Amniotic sac
2. Umbilical cord
Lesson 1
Embryonic Growth
Structures Formed During Embryonic Growth
As the embryo grows, its cells continue to divide, forming
three tissue layers thatThe
later
become various body systems.
umbilical
cord is a ropelike
During this time, two
important
structure
that structures form outside the
embryo:
connects the embryo
and the mother’s
1. Amniotic sac
placenta.
2. Umbilical cord
Lesson 1
Embryonic Growth
Substances Passed to the Embryo
Although the blood supply of the mother and the developing
embryo are The
keptplacenta
separate, materials diffuse from one blood
is athe
thick,
blood-rich
supply to
other
through the umbilical cord.
tissue that lines the
Nutrients
andofoxygen
pass from the mother’s blood to the
walls
the uterus
embryo,
and wastes
fromand
the embryo diffuse into the mother’s
during
pregnancy
blood. nourishes the embryo.
If a pregnant female uses harmful substances, they can cross
the placenta and harm the developing embryo.
Lesson 1
Fetal Development
Trimesters
After about the
The time from conception to birth
is usually
eighth
week,about
the nine full
months.
developing group of
cells is called a
These nine months are divided into three 3-month periods
fetus.
called trimesters.
During the period of growth in the uterus, the fetus develops
in preparation for living outside the mother’s body.
Lesson 1
Stages of Birth
Changes Experienced During Labor
Many females experience weak,
irregular
Labor
is themuscular
final
contractions of the uterusstage
for weeks
or even months
before
of pregnancy
in
the baby is born.
which the uterus
contracts and pushes
As the time approaches for
baby
born, however,
thethe
baby
outtoofbe
the
these contractions become
regular,body.
stronger, and closer
mother’s
together.
The stronger contractions induce labor.