Download The Endocrine System

The Endocrine
System
Section 1
Objectives
䊳
Describe the general
roles of the endocrine
system.
䊳
Identify the glands of the
endocrine system.
Objectives
Before class begins, write the objectives
on the board. Have students copy the
objectives into their notebooks at the
start of class.
1. Focus
Vocabulary
•
•
•
•
•
endocrine gland
hormone
hypothalamus
pituitary gland
puberty
Warm-Up Health Stats
Call on students to describe in words
the trends in growth rates shown in
the graph. Ask students to stand to
facilitate comparison of heights of
boys and girls in the class. Class gender differences are likely to be similar to the gender differences in the
graph. Ask students what might
explain the gender differences.
The Endocrine
System
Health Stats What trends in growth rate does this graph
show?
Average Height of American Teens
70
Males
Height (inches)
Section 1
65
60
Females
55
50
0
9
10
11
12
13 14 15 16
Age (years)
17
18
19
20
Does your observation of classmates support the trends
shown in the graph? Explain.
What Is the Endocrine System?
Teaching Transparency W61
How much have you grown in the past year? When will you reach your
adult height? Your growth rate is one of the many functions controlled
by your body’s endocrine system. The endocrine system regulates longterm changes in the body such as growth and development. It also
controls many of your body’s daily activities. Two examples of daily
activities include your body’s use of energy from a meal and its response
to stress.
Endocrine Glands Your endocrine system is made up of a group of
organs, called endocrine glands (EN duh krin). An endocrine gland produces and releases chemical substances that signal changes in other parts
of the body. Some of your body’s glands, such as sweat glands, release
their chemicals into tiny tubes called ducts. The ducts carry the chemicals
to the place where they will be used. Endocrine glands, on the other hand,
do not have ducts. Instead, they release substances directly into the bloodstream. The blood then carries those substances throughout the body.
460
Chapter 18
Sensitive Issues
This section introduces puberty, which
may be a sensitive issue to students
who are at or near puberty. These
students may be self-conscious about
the obvious physical changes they are
experiencing. Take care in asking
students to relate the content to
personal experience. They may not
be comfortable doing this.
460
Chapter 18
and Health
L3 Calculating Rates
You can use the data in the Warm-Up
graph to give students a chance to practice calculating rates. Have them use the
average heights of boys and girls at ages
12, 13, 14, and 15 years to calculate average annual rates of growth in height. (For
boys, the rates are 3 in/yr from ages 12 to
13 yr, 4 in/yr from ages 13 to 14 yr, and
3 in/yr from ages 14 to 15 yr. For girls, the
corresponding rates are 4 in/yr, 2 in/yr, and
1 in/yr, respectively.) Discuss how the rates
give a different perspective on gender differences in growth by showing how fast
growth occurs, rather than how much
growth occurs.
2. Teach
Growth hormone
regulates your growth
to adult height.
L3 EL Reading/Note Taking 18-1
L2 Adapted Reading/Note Taking 18-1
What Is the Endocrine
System?
L2 Active Learning
Adrenaline directs your
response to sudden
stress or fear.
Testosterone controls beard
growth in males.
Hormones A chemical substance produced by an endocrine gland is
known as a hormone. You can think of a hormone as a chemical messenger. Each hormone has a specific function and specific “targets” in the body.
Once released into the bloodstream, a hormone travels to its target cells,
where it turns on, turns off, speeds up, or slows down the activities of those
cells. For example, targets of the hormone adrenaline include cells in your
heart, muscles, and brain. Adrenaline causes a faster heartbeat, tensing of
the muscles, and increased alertness—your “fight-or-flight” response.
The endocrine system is kept in balance by the coordinated action of
various hormones. For example, a hormone from one gland may turn on
the production of a different hormone by a second gland. In turn, the
hormone from the second gland signals the first gland to stop releasing its
hormone. By this system of checks and balances, the endocrine system
keeps the body’s activities functioning smoothly.
Connect to
YOUR LIFE
FIGURE 1 Hormones play
many roles in the body.
EL Class Discussion
For students who are having trouble
understanding the role of endocrine
glands, use an analogy. Have students
describe the relationship between a
conductor and an orchestra. (The
conductor signals the orchestra how
to play.) Discuss how endocrine glands
regulate body functions in a similar way.
Describe a time when you experienced a surge
of adrenaline.
Functions of Endocrine Glands
Each of your endocrine glands plays a specific, important role in
your body. The endocrine glands include the hypothalamus, pituitary
gland, thyroid and parathyroid glands, thymus gland, adrenal glands,
pancreas, and reproductive glands.
Connect to Sample answer: I experienced
YOUR LIFE a surge of adrenaline when I
Hypothalamus The hypothalamus (hy poh THAL uh mus), an
endocrine gland located in the brain, is actually part of both the nervous
and the endocrine systems. For example, nerve signals from the hypothalamus control body temperature and feelings of sleep and hunger, and
hormones from the hypothalamus control the body’s water levels. The hypothalamus also produces a class of hormones called “releasing hormones”
that signal the release of hormones from another region of the brain.
rode on a roller coaster.
Functions of Endocrine
Glands
L2 Active Learning
Reproduction and Heredity 461
L1 Special Needs
Students who need extra help, as well as
visual and tactile learners, may learn more
about the endocrine system by actively making their own drawing of it. Give each student a sheet of tracing paper or thin unlined
paper. Ask students to trace the outline of
the person in Figure 2. Then have them add
the endocrine glands to their drawing, label
Demonstrate with a simple role-play
how an endocrine hormone acts as a
chemical messenger. Explain that you
will play the role of an endocrine gland.
Select a nearby student to play the role
of a hormone and a student across the
room the role of a target cell. Write a
note that reads, “When you get this
note, raise your hand.” Hand the note
to the “hormone,” and tell the “hormone” to carry it to the “target cell,”
who should respond by raising his or
her hand. After the demonstration, call
on volunteers to describe the role of an
endocrine hormone, based on what
they observed.
the glands, and write one function of each
gland under its label. Help students reword
functions that are expressed in difficult
terms. For example, you might reword the
function of the thyroid gland as, “controls
how fast the body breaks down food to get
energy.” Check students’ completed drawings for errors and omissions.
Have students create an eight-column,
3-row table. Along the first row, have
them fill in the names of eight different
endocrine glands (listed in the boldfaced sentence in their text). Tell them
to fill in details about each of the glands
in the next two rows—gland locations
and functions—as they continue reading
this section.
Reproduction and Heredity
461
Chapter 18, Section 1
The Endocrine System
L2 Visual Learning: Figure 2
Teaching Transparency 49
Have pairs of students write the names
of the endocrine glands on one set of
index cards and the functions of the
glands on another set of index cards,
using information in the figure. Then
have partners try to match the two sets
of cards. Students should repeat the
activity until they have learned the
functions of all the endocrine glands.
Caption Answer The adrenal glands are
located on top of the kidneys. They
release hormones that trigger the
body’s response to sudden stress, affect
salt and water balance in the kidneys,
and influence general metabolism.
Hypothalamus
The hypothalamus links the nervous system
and the endocrine system and controls
many of the pituitary gland functions.
Thyroid Gland
The thyroid gland regulates
the body’s overall metabolic
rate and controls calcium
levels in the bloodstream.
Pituitary Gland
The pituitary gland controls other endocrine
glands and regulates growth rate, reproduction,
and metabolism.
Parathyroid Glands
Four tiny parathyroid glands
regulate levels of calcium and
phosphorus—minerals that
are necessary for proper
bone and tooth formation
and for muscle and
nerve activity.
Thymus Gland
Hormones released by the thymus gland
help the immune system develop during
childhood. By adolescence, this gland
has shrunk considerably in size.
Adrenal Glands
These glands release several hormones.
Adrenaline triggers the body’s response
to sudden stress. Other hormones affect
salt and water balance in the kidneys
and general metabolism.
L3 Building Health Skills
Accessing Information Have students
assume they have been feeling unusually tired for no apparent reason. As a
homework assignment, ask them to use
a library reference book (e.g., medical
encyclopedia) to find out (1) whether
tiredness can be a symptom of a thyroid
problem, and (2) what type of doctor
treats thyroid problems. During the
next class, call on volunteers to share
what they learned. (Tiredness can be a
symptom of hypothyroidism, or inadequate thyroid hormone. Endocrinologists
treat thyroid problems and problems of
other endocrine glands.) Ask: How
could you locate an endocrinologist in
your community? (Sample answers:
Look in the yellow pages of the local
telephone directory; ask your family
doctor.)
Pancreas
The pancreas is a
large gland, located
behind the stomach,
that controls sugar
levels in the blood.
Ovaries
The female reproductive glands
release sex hormones that
regulate egg maturation and
control changes in a female’s
body at puberty.
Testes
The male reproductive
glands release a sex
hormone that regulates
sperm production and
controls changes in a
male’s body at puberty.
Each of the endocrine
glands plays an important
regulatory role in the body.
Interpreting Diagrams Where
are the adrenal glands located?
What is their function?
FIGURE 2
Female
462
Male
Chapter 18
TEENS Are Asking . . .
Q:
I’m the youngest boy in my class. I always
used to be about as tall as my friends, but
now they are all at least three inches taller.
Will I always be shorter than my friends?
A:
If you were as tall as your friends
throughout childhood, most likely you will
be as tall as they are by the time you are an
adult. At your age, you probably are about
to begin a period of very rapid growth. You
462
Chapter 18
are likely to grow six or seven inches over
the next couple of years. Most likely, your
friends, who are older, have already begun
this period of very rapid growth. Try to be
patient—you will probably catch up with
your friends soon. If you are still worried
about your height, you should talk with a
doctor about your concerns.
Pituitary Gland “Releasing hormones” from the hypothalamus
signal the release of hormones from a pea-sized endocrine gland in the
brain, called the pituitary gland (pih TOO ih tehr ee). The pituitary controls many of your body’s functions. These functions include growth,
reproduction, and metabolism. Metabolism is the process by which you
obtain energy from food.
Some pituitary hormones act as “on” switches for other endocrine
glands. For example, one pituitary hormone signals the thyroid gland to
release hormones essential for normal metabolism. Other pituitary hormones control body activities directly. For example, growth hormone
released by the pituitary gland regulates growth throughout your body
from infancy to adulthood.
L3 Online Activity
PHSchool.com
For: More on endocrine
glands
Visit: PHSchool.com
Web Code: ctd-6181
Use the Web Code to
access an online activity about coping
with stress. Have students complete the
Web activity.
3. Assess
Evaluate
These assignments can help you assess
students’ mastery of the section content.
Other Endocrine Glands Endocrine glands are found throughout
the body, as shown in Figure 2. Notice the range of body functions that
your endocrine system controls—from your blood sugar level over the
course of a day to the long-term changes in your body that you experience
as a teen.
The reproductive glands are an important part of the endocrine
system. In males, the reproductive glands consist of two testes, and in
females, two ovaries. The reproductive glands work at low levels in both
boys and girls until about the age of ten, when puberty typically begins.
Puberty is the period of sexual development during which a person
becomes sexually mature and physically able to reproduce.
Puberty starts when the hypothalamus signals the pituitary gland to
begin producing two hormones. Those hormones in turn signal the reproductive glands to produce sex hormones. Sex hormones activate several
changes in your outward appearance during puberty. Sex hormones also
control reproductive functions inside your body. You will learn more about
the reproductive glands and their hormones in the next two sections.
Section 1 Review
Answers appear below.
Teaching Resources
• Practice 18-1
• Section 18-1 Quiz
L2 Reteach
Play a quiz game in which you describe
the functions of the endocrine glands
and students try to name the glands.
Go around the room, calling on one
student after another, until most students show mastery of the information.
L4 Enrich
Teaching Resources
Health at School
Section 1 Review
Key Ideas and Vocabulary
1. What roles does the endocrine system play in the
body?
2. What is a hormone? Explain how hormones reach
the cells where they have their effect.
3. List the glands of the endocrine system.
4. What is the hypothalamus? How does it interact
with the pituitary gland?
Critical Thinking
Adrenaline in Action Interview a musician or an
athlete at your school about the role that
adrenaline might play during a performance or
game. Find out the conditions under which they
have noticed this response and whether it helped
their performance. Write a transcript of your
interview.
6. Applying Concepts A driver brakes suddenly when
a dog darts out in front of her car. How did the
endocrine system aid her quick response?
5. Relating Cause and Effect How is the onset of
puberty related to the endocrine system?
• Enrich 18-1
Health at
School
Adrenaline in Action Students can
interview anyone who has ever had
“butterflies” in the stomach or a
racing heart because of an upcoming
performance. Such a reaction can
either help or hinder a performance,
depending on the individual. Students
can record the interview (with the
interviewee’s permission) and play it
back later to transcribe it.
Reproduction and Heredity 463
Section 1 Review
1. It regulates long-term changes in the body,
such as growth and development, and controls many of the body’s daily activities.
2. A hormone is a chemical substance produced by an endocrine gland. Hormones
travel through the bloodstream to reach
target cells.
3. hypothalamus, pituitary gland, thymus
gland, adrenal glands, thyroid gland,
parathyroid glands, pancreas, and ovaries
or testes
4. The hypothalamus is an endocrine gland
located in the brain. It produces hormones
called “releasing hormones” that signal the
pituitary gland to release its hormones.
5. Puberty starts when the hypothalamus signals the pituitary gland to
begin producing two hormones.
Those hormones in turn signal the
reproductive glands to produce sex
hormones. Sex hormones activate
several changes in outward appearance and inside the body.
6. The adrenal glands released adrenaline, which increased alertness.
Reproduction and Heredity
463