Section 18.1 The Endocrine System
Health Stats What trends in growth rate does this graph show?
Does your observation of classmates support the trends shown
in the graph? Explain.
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Section 18.1 The Endocrine System
The Endocrine System
Goals/ Objectives
Describe the general roles of the endocrine
system.
Identify the glands of the endocrine system.
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Section 18.1 The Endocrine System
Key Terms
endocrine gland
hormone
A gland that produces and releases chemical
substances that signal changes in other parts of
the body.
A chemical substance produced by an
endocrine gland.
hypothalamus
An endocrine gland in the brain that is part of
both the nervous and endocrine systems.
pituitary gland
An endocrine gland in the brain that controls
many of the body’s functions, including growth,
reproduction, and metabolism.
puberty
The period of sexual development during which
a person becomes sexually mature and
physically able to reproduce.
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Section 18.1 The Endocrine System
Key Terms
Endocrine System
The body system that consists of glands that
produce hormones.
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Section 18.1 The Endocrine System
What Is the Endocrine System?
• The endocrine system regulates long-term changes
in the body such as growth and development.
• It also controls many of your body’s daily activities.
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Section 18.1 The Endocrine System
Endocrine Glands
• Your endocrine system is made up of a group of
organs, called 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.
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Section 18.1 The Endocrine System
Hormones
• A chemical substance produced by an endocrine
gland is known as a hormone.
• You can think of a hormone as a chemical
messenger.
• The endocrine system is kept in balance by the
coordinated action of various hormones.
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Section 18.1 The Endocrine System
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Section 18.1 The Endocrine System
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Section 18.1 The Endocrine System
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Section 18.1 The Endocrine System
Functions of the Endocrine Glands
The endocrine glands include the
• hypothalamus
• pituitary gland
• thyroid and parathyroid glands
• thymus gland
• adrenal glands
• pancreas
• reproductive glands
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Section 18.1 The Endocrine System
The Endocrine System
Thyroid Gland
The thyroid gland regulates
the body’s overall metabolic
rate and controls calcium
levels in the bloodstream.
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.
Pancreas
The pancreas is a large
gland, located behind the
stomach, that controls
sugar levels in the blood.
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Section 18.1 The Endocrine System
The Endocrine System
Hypothalamus
The hypothalamus links the nervous system and
the endocrine system and controls many of the
pituitary gland functions.
Pituitary Gland
The pituitary gland controls other endocrine glands and
regulates growth rate, reproduction, and metabolism.
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.
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Section 18.1 The Endocrine System
The Endocrine System
Ovaries
Testes
The female reproductive glands
release sex hormones that
regulate egg maturation and
control changes in a female’s
body at puberty.
The male reproductive
glands release a sex
hormone that
regulates sperm
production and
control changes in a
male’s body at
puberty.
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Section 18.1 The Endocrine System
Hypothalamus
• The hypothalamus, an endocrine gland located in the
brain, is actually part of both the nervous and the
endocrine systems.
• Nerve signals from the hypothalamus control body
temperature and feelings of sleep and hunger.
• Hormones from the hypothalamus control the body’s
water levels.
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Section 18.1 The Endocrine System
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.
• The pituitary controls many of your body’s functions.
• These functions include
• growth
• reproduction
• metabolism
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Section 18.1 The Endocrine System
Other Endocrine Glands
• The reproductive glands are an important part of the
endocrine system.
• Puberty is the period of sexual development during
which a person becomes sexually mature and
physically able to reproduce.
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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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