Chapter 33. Stress Hurts
Learning Objectives
Describe the harmful effects of chronic stress on several organ systems, including the heart, the brain, and the immune system.
Review
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1. Stress is the process by which we appraise and cope with events (called stressors) that threaten and challenge us. Stress can be good for us: It arouses us and energizes us in times of crisis, and it motivates us to achieve significant accomplishments. However, research has demonstrated that our body pays a heavy price for the energizing effects of stress.
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2. When threats or challenges persist, chronic stress can destroy our health and shorten our life—especially if we compound the problem by engaging in unhealthy behaviors. Most of the health problems come from persistently high levels of glucocorticoid stress hormones such as cortisol, which combat inflammation and mobilize glucose that the body can burn for energy.
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3. On the next pages, we will explore the damaging effects of glucocorticoids on the cardiovascular system, the digestive system, the brain, and the immune system.
Practice 1: Stress Damages Body Tissues
Practice 1: Stress Damages Body Tissues
Roll over the brain, the heart, and the digestive tract to see how the body is affected by stress.
Recent studies have demonstrated that elevated levels of glucocorticoids can cause permanent damage to neurons in a part of the brain called the hippocampus (a structure involved in learning and memory). New evidence from brain scans suggests that the hippocampus is smaller than normal in chronically depressed patients (who tend to have elevated glucocorticoid levels in their bloodstreams) and military veterans with several years of combat exposure. The constant high levels of stress hormones in these individuals actually may have caused the hippocampus to shrink. Stress can damage your brain.
Chronic stress raises blood pressure, which over time causes damage to the heart and blood vessels and increases the risk of stroke. Also, high levels of glucocorticoids cause fat cells to release fatty acids into the bloodstream for fuel. If we don't need to burn the fat for energy, it builds up on the walls of our blood vessels (especially those damaged by high blood pressure), reducing blood flow to the brain and muscles, increasing the risk of heart attack. Stress can damage your heart.
Stress causes a reduction in enzyme production and a reduction in blood flow to the stomach and intestines, making the lining of the stomach more vulnerable to damage from hydrochloric acid and ulcer-causing bacteria. Stress can damage the digestive tract.
Practice 2: Stress Suppresses the Immune System
Practice 2: Stress Suppresses the Immune System
Select the PLAY button to watch the effects of stress hormones on the immune system.
Stress weakens your body’s defenses against disease. Students are more likely to become ill during or immediately after a period of high stress, such as exam week. Why does this happen?
Our immune system contains white blood cells called lymphocytes that identify and kill foreign microorganisms that invade the body. Stress hormones, particularly glucocorticoids, suppress the immune system, making it less effective in defending the body against disease. Here is how that suppression happens.
Quiz 1
Quiz 1
For each statement, indicate whether the statement is True or False. When responses have been indicated for all the statements, select the CHECK ANSWER.
| True | False | |
|---|---|---|
Stress damages the brain by keeping it in a chronic state of activity, thus preventing the normal processing and consolidation of memories. |
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Stress damages the digestive tract by suppressing enzyme production and reducing blood flow to the stomach and intestines. |
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Stress damages the heart by raising blood pressure and releasing excess fat into the bloodstream, which tends to accumulate on the coronary artery walls. |
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Stress damages the digestive tract by speeding up the rate of digestion in the stomach and intestines. |
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Stress damages the brain by harming neurons in the hippocampus, and perhaps shrinking the hippocampus. |
Quiz 2
Quiz 2
For each statement, indicate whether the statement is True or False. When responses have been indicated for all the statements, select the CHECK ANSWER.
| True | False | |
|---|---|---|
Glucocorticoids such as cortisol provide the glucose that the immune system needs in order to do its job. |
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Stress interferes with the immune system's functioning by suppressing the creation of lymphocytes. |
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Persons who are under prolonged stress are at increased risk for developing infectious diseases. |
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Glucocorticoids may prevent lymphocytes from mobilizing a coordinated defense against invading microorganisms. |
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Lymphocytes are red blood cells that carry oxygen from the lungs to the body's other organ systems. |