The skin (4.9) and white blood cells (8.1) have major roles in

defense. This chapter also draws on what you have learned

about proteins (2.11) and how cells take up substances by

the mechanisms of endocytosis and phagocytosis (3.11).

You will now learn more about how the cardiovascular

system interacts with the bodywide network of vessels and

organs that form the lymphatic system (7.1). You’ll also

see how circulating blood (7.3) serves as a highway for

defensive cells and substances.

Links to EarLiEr ConCEpts

kEy ConCEpts

Defenses against Disease

The body’s defenses against disease

threats include physical barriers and

two interacting sets of cells and pro-

teins. The lymphatic system has key

roles in defense. Sections 9.1–9.3

Top: © Cengage Learning; Middle: From Frances Sienkiewicz Sizer; Eleanor

Noss Whitney, Nutrition: Concepts and Controversies, © 2002 Cengage

Learning; Bottom: Colin Hawkins/Cultura/Getty Images

Innate and Adaptive Immunity

Inborn defenses provide innate

immunity, while encounters with

agents of disease provide adaptive

immunity. White blood cells and

defensive proteins act in both kinds

of immune responses. Sections

9.4–9.8

Immune System Malfunctions

Flawed or failed immune mechanisms

result in allergies, cancer, autoimmune

disorders, and immune deficiencies

such as AIDS. Section 9.9

theclimbofmylife.com

Kelly Perkins has climbed some of the highest

mountains in the world—all while relying on the heart that was

transplanted into her chest in 1995. She underwent the transplant

after a viral infection caused inflammation that seriously damaged

her own heart. After her surgery, Kelly took up mountain climbing,

trekking up dozens of peaks around the world, including 14,505-foot

Mt. Whitney in California. Her memoir about her experiences became

a best-selling book that continues to inspire transplant patients

everywhere.

Kelly’s story launches our study of the body’s powerful

responses to harmful viruses, bacteria, and many other health

threats. In most cases, such defensive weapons work amazingly

well to preserve and restore our health.

immUnity anD DisEasE

9

155

Copyright 2016 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).