1. Content Vocabulary nervous system hormonal system hormone gland
stress hormones
immune system
immunity

2. The Nervous System
The nervous system responds to challenges by producing reactions that restore normal body conditions. 2

3. The Nervous System
The nervous system plays a key role in how your body deals with stress.
The nervous system creates a set of reactions to restore normal conditions inside the body.
nervous system
The body system that manages the body’s activities by sending and receiving messages between the brain, spinal cord, and nerves 3

4. The Hormonal System
The hormonal system consists of glands that produce hormones. 4

5. The Hormonal System
The hormonal system works with the nervous system to maintain communication among body organs.
hormonal system
a system of glands that control body functions in cooperation with the nervous system 5

6. The Hormonal System
Hormones are released by glands and travel in the blood stream to one or more target organs, where they bring about responses.
hormone
A chemical that serves as a messenger
gland
An organ that secrets one or more hormones in response to information about changing body conditions. 6

7. The Hormonal System
Stress hormones regulate the body’s activities during emergencies and when the body is in a period of stress.
stress hormones
The hormones that control the body’s response to stress 7

8. The Immune System
The immune system is the body’s main defense against disease. Unrelieved stress can weaken the immune system. 8

9. The Immune System
The immune system includes white blood cells, bone marrow, the thymus gland, and the spleen.
immune system
The cells, tissues, and organs that protect the body from disease 9

10. White blood cells are the main cells of immunity.
The Immune System
White blood cells are the main cells of immunity.
White blood cells are made in bone marrow and make antibodies to protect against infection.
immunity
The body’s capacity for identifying, destroying, and disposing of disease-causing agents 10

11. The Immune System
The activity of the immune system is lower than normal during times of stress.
Long periods of unrelieved stress can reduce the number of white blood cells and make a person likely to suffer disease. 11

12. Section Review: Reviewing the Vocabulary
What is the nervous system?
nervous system
The body system that manages the body’s activities by sending and receiving messages between the brain, spinal cord, and nerves

13. Section Review: Reviewing the Vocabulary
What is a hormone?
hormone
A chemical that serves as a messenger