Chapter 23 The Circulatory, Respiratory, Digestive, and Excretory ...

• Food allergies occur when the immune system reacts to substances in food as though they were
harmful “foreign invaders.” Foods that are most likely to cause allergies are pictured in Figure
23.26. Symptoms of food allergies often include vomiting and diarrhea.
• Ulcers are sores in the lining of the stomach or duodenum that are usually caused by bacterial
infections. Symptoms typically include abdominal pain and bleeding. You can see how stomach
ulcers develop at this link: http://www.youtube.com/watch?v=4bXZRgJ-1fk.
• Heartburn is a painful burning sensation in the chest caused by stomach acid backing up into the
esophagus. The stomach acid may eventually cause serious damage to the esophagus unless the
problem is corrected.
Figure 23.26: These foods are the most common causes of food allergies.
KQED: Hepatitis C: The Silent Epidemic
Hepatitis C is a virus that causes cirrhosis of the liver and liver cancer. It’s the leading cause for liver
transplants in the U.S., and an estimated 4 million Americans have the disease. Current treatments are
difficult to tolerate and are often ineffective, but recent breakthroughs from scientists may soon produce a
cure for the disease that claims more than 10,000 American lives each year. See http://www.kqed.org/
quest/television/hepatitis-c-the-silent-epidemic for additional information.
Food and Nutrients
Did you ever hear the saying, “You are what you eat”? It’s not just a saying. It’s actually true. What
you eat plays an important role in your health. Eating a variety of the right types of foods promotes good
health and provides energy for growth and activity. This is because healthful foods are rich in nutrients.
Nutrients are substances the body needs for energy, building materials, and control of body processes.
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