1. Growth and Development
Chapter 17
Growth and Development
Lesson 1
The Beginning of Life
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2. The joining together of a male sperm cell and a female egg cell
fertilization
The reproductive cell from the female that joins with a sperm cell to make a new life
egg cell
The cell from the male that enters the egg cell during fertilization
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sperm cell

3. The developing organism from the end of the eighth week until birth
A pear-shaped organ inside a female’s body where the embryo is protected and nourished
uterus
The developing organism from fertilization to about the eighth week of its development
embryo
The developing organism from the end of the eighth week until birth
Click to reveal the definitions.
fetus

4. A tube that connects the mother’s placenta to the fetus
A thick, rich tissue that lines the walls of the uterus during pregnancy and that nourishes the fetus
placenta
umbilical cord
A tube that connects the mother’s placenta to the fetus
Click to reveal the definitions.
cervix
The entry to the uterus

5. In this lesson, you will learn to
identify the building blocks of life.
explain how a single cell develops into a baby.
describe the stages of birth.
access information on the physical and emotional changes a pregnant female experiences.

6. Analyzing a Graphic
Using Figure 17.2 on page 452, summarize the process that a fetus goes through during the months before its birth.

7. Building Blocks of Life
The cell is the basic unit of life.
Cells that do similar jobs come together to form tissues.
The human body is composed of trillions of cells, each with its own job to do.
Tissues combine to form organs.
Organs come together to form body systems.

8. Fertilization takes place in the mother’s reproductive system.
fertilization The joining together of a male sperm cell and a female egg cell
Your body started as a fertilized cell.

9. Fertilization
As soon as a sperm cell enters the egg cell, a film is produced around the egg preventing any additional sperm cells from entering.
sperm cell The cell from the male that enters the egg cell during fertilization
The egg cell is fertilized inside one of the female’s two fallopian tubes.
Once fertilization takes place, a new life begins to grow.
egg cell The reproductive cell from the female that joins with a sperm cell to make a new life

10. Growth During Pregnancy
In the uterus, the egg develops into a cluster of cells called an embryo.
uterus A pear-shaped organ inside a female’s body where the embryo is protected and nourished
The egg travels to the uterus once it has been fertilized.
The embryo attaches itself to the inside wall of the uterus where the cells continue to divide into cells that do specific jobs.
embryo The developing organism from fertilization to about the eighth week of its development

11. Growth During Pregnancy
The fetus grows and develops for about nine months.
fetus The developing organism from the end of the eighth week until birth
Over time, cells combine to form tissues. Tissues that do similar jobs combine to form organs, and organs combine to form body systems.
By the end of the eighth week, the embryo’s organs have started to develop.

12. Growth During Pregnancy
Month
Development 1
The heart, brain, and lungs of the embryo are forming. 2
The heart of the fetus begins to beat, and organs are developing. 3
The fetus begins to move around. It weighs about 1 ounce. 4
The facial features of the fetus are well developed. 5
The eyelashes and nails of the fetus appear and its heartbeat can be heard. 6
The fetus can hear, kick, swallow, and open and close its mouth. 7
The fetus can open its eyes and move its arms and legs freely. 8
The fetus’s hair is getting longer and its skin is smoother. 9
The baby’s organs are all ready to work on their own.
Month Weight and Height
End of month one: One third of an inch long
End of month two: 1 inch long
End of month three: 1 ounce, 3 inches long
End of month four: 6 ounces, 5 inches long
End of month five: 1 pound, 10 inches long
End of month six: 1.5 pounds, 12.5 inches long
End of month seven: 2 to 2.5 pounds, 14.5 inches long
End of month eight: 4 pounds, 18 inches long
End of month nine: 7 to 9 pounds, 18 to 20 inches long

13. Growth Inside the Uterus
The fetus receives nourishment from the placenta through the umbilical cord.
placenta A thick, rich tissue that lines the walls of the uterus during pregnancy and that nourishes the fetus
The umbilical cord also carries away the wastes produced by the growing fetus.
umbilical cord A tube that connects the mother’s placenta to the fetus

14. Growth Inside the Uterus
Substances such as tobacco, alcohol, and other drugs can do harm to a fetus.

15. The cervix begins to dilate.
Stages of Birth
The cervix begins to dilate.
Stage One
Strong contractions push the baby through the cervix and out of the mother’s body.
Stage Two
Muscles of the uterus keep contracting until the placenta is pushed out of the mother’s body.
Stage Three
Stage one:
The muscles in the uterus begin to squeeze and release gently. These muscle movements are called contractions and they signal that birth is starting.
Stage Two:
The cervix continues to dilate, preparing for the baby to pass through. Contractions become very strong.
Stage Three:
The placenta is no longer needed.
cervix The entry to the uterus

16. What I Learned Vocabulary Define fertilization. Lesson 1 Review
Fertilization is the joining together of two special cells, one from each parent, to form one cell.

17. Lesson 1 Review
What I Learned
Identify What structure carries food and oxygen from the mother’s body to her developing fetus?
The umbilical cord carries food and oxygen to a developing fetus.

18. What I Learned Recall How is an organ different from a body system?
Lesson 1 Review
What I Learned
Recall How is an organ different from a body system?
Organs are formed from tissues. Body systems are groups of organs that work together.

19. Lesson 1 Review
Thinking Critically
Analyze How does a woman know that her baby is ready to be born?
A pregnant female knows her baby is ready to be born when she has muscle contractions.

20. Lesson 1 Review
Thinking Critically
Apply Janice is thinking about having a baby, but she likes to smoke cigarettes. Based on what you’ve learned in this lesson, what advice would you give her?
Janice should stop smoking before she becomes pregnant because tobacco harms the fetus.

21. Growth and Development
End of
Chapter 17
Growth and Development
Lesson 1
The Beginning of Life
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