The endocrine system is made up of glands that release hormones directly into the bloodstream to regulate long-term body changes and daily activities. The glands include the hypothalamus, pituitary gland, thyroid and parathyroid glands, thymus gland, adrenal glands, pancreas, and reproductive glands. Hormones are chemical messengers released by endocrine glands that signal changes in other parts of the body and keep the endocrine system in balance.

1. Section 18.1 The Endocrine System
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• The endocrine system regulates long-term changes
in the body such as growth and development.
What Is the Endocrine System?
• It also controls many of your body’s daily activities.

2. Section 18.1 The Endocrine System
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• Your endocrine system is made up of a group of
organs, called endocrine glands.
Endocrine Glands
• An endocrine gland produces and releases
chemical substances that signal changes in other
parts of the body.
• Endocrine glands release substances directly into
the bloodstream.

3. Section 18.1 The Endocrine System
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• A chemical substance produced by an endocrine
gland is known as a hormone.
Hormones
• You can think of a hormone as a chemical
messenger.
• The endocrine system is kept in balance by the
coordinated action of various hormones.

4. Section 18.1 The Endocrine System
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The endocrine glands include the
Functions of the Endocrine Glands
• hypothalamus
• pituitary gland
• thyroid and parathyroid glands
• thymus gland
• adrenal glands
• pancreas
• reproductive glands

5. Section 18.1 The Endocrine System
Questions
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?
5. How is the onset of puberty related to the endocrine
system?
6. A driver brakes suddenly when a dog darts out in front of
her car. How did the endocrine system aid her quick
response?
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