cw
Name
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Before doing this lab, have students read section 25:1 in the text.
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Class
r----- 25-2
Period
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What Changes Occur During Birth?
FIGURE 2.
•
A human baby develops for about 38 weeks inside the mother. Then
labor begins and the baby is born. 'What changes take place during and after
birth? Why must a doctor sometimes have to perform a caesarean operation
to help in delivery?
INTERPRETATION
Process Skills: interpreting scientific iIIustraOBJECTIVES
tions, interpreting data, scientific terminology,
In this activity, you will:
summarizing
a. compare the changes that occur during birth.
b. learn why a caesarean delivery may be needed,
c. compare a delivery through the birth canal with a caesarean delivery.
placenta
few
minutes
after birth
during
birth
KEYWORDS
Define the following keywords:
caesarean
the birth of a baby in which the uterus must be cut open
2. Answer yes or no to each of the following questions in Table l.
contractions
muscles of the uterus shortening during birth
fetus
an embryo that has all of its body systems
labor
contractions of the uterus during birth
placenta
uterus
-----
an organ that connects the embryo to the mother's uterus
an organ in which a fertilized egg will develop
MATERIALS
..
... ~-
- - - _ . "OM _ •••••
Three days
before birth
Two hours
before birth
During
birth
Few minutes
after birth
Is baby inside the uterus?
yes
yes
yes
no
Is baby inside the vagina?
no
no
yes
no
Is baby outside the mother's body?
no
no
no
yes
yes
yes
yes
no
Has the sac broken?
no
yes
yes
yes
Are contractions occurring?
no
yes
yes
.yes
yes
yes
yes
no
yes
yes
yes
yes
yes
yes
yes
no
Is the placenta being pushed out?
no
no
no
yes
Has the vagina opened?
no
yes
yes
yes
yes
yes
yes
no
no
yes
yes
yes
yes
yes
yes
no
metric' ruler
Is baby inside the sac?
PROCEDURE
Part A. Stages of Birth
1. Look at the diagrams of four stages of birth shown in Figures 1 and 2.
FIGURE 1.
Is baby attached to the cord?
I.s the cord attached to
the placenta?
Is the placenta attached
to the uterus?
.~~
three days
before birth
Is baby attached to
the mother?
Has liquid been lost
from the sac?
Is baby still dependent on
the mother?
two hours
before birth
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Period
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Trait
Part B. What Is a Caesarean Birth?
1. Look at the diagram in Figure
3 that shows the outline. of the
pelvis and the head· of a fetus
just before the time of birth.
2. Note carefully that the head
must be able to pass through
the opening in the pelvis during
birth.
3. Measure line a. This represents
the width of the opening in the
pelvis.
4. Measure line b. This represents
the width of the head of the
fetus.
FIGURE 3. Sizes of pelvis and head of fetus
b. width of fetus head
6. Notice that this fetus would not
be able to pass through this
pelvis opening.
7. A caesarean operation must be
done to deliver the baby.
8. Look at how a caesarean birth
is done in Figure 4. This is
usually done before the mother
goes into labor.
9. To compare a birth canal
delivery with a caesarean
delivery, answer the questions
in Table 2.
Caesarean
Does the fetus pass through opening in the pelvis?
yes
no
Does the fetus pass through the vagina?
yes
no
Does the placenta move through the vagina?
yes
no
Is the fetus lifted from the uterus?
no
yes
Is the uterus cut open?
no
yes
Is the sac cut open?
no
yes
Must the cord be cut to separate the fetus from the placenta?
yes
yes
Do contractions occur?
yes
no
the mother's uterus and the fluid-filted sac
2. What is the job of the placenta?
31 mm
34 mm
.
.
Opening through
which fetus and placenta are
remOV.d~
_
carries food and oxygen to embryo and carries
waste from the embryo
3. What is the job of the cord? connects embryo
to placenta
-------------4. What is meant by the word labor? contractions of the muscles of the uterus during
birth
5. The placenta is sometimes called the afterbirth. Why is this a good name for this
part? The placenta is "born" or lea~es the uterus after the baby is bor~_.
6. List several changes that take place several hours before birth.
are occurring.
(2) The vagina has opened.
_
(1) Contractions
(3) The liquid is lost from the sac.
7. List several changes that take place a few minutes after birth.
(1) The baby is out of the mother's body.
(2) The baby is out of the sac.
(3) The baby is not attached to the cord or the mother.
attached to the uterus.
placenta
FIGURE 4. Caesarean birth
~
_.~
Birth canal
QUESTIONS
1. What two body parts surround and protect the fetus as it develops?
a
5. Record your data here:
a. width of pelvis opening
- _•.•
(4) The placenta is not
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