CHAPTER 6
Understanding Stress, Immunity, and Disease
Lecture Outline
I. Physiology of the Immune System
The immune system consists of tissues, organs, and processes that protect the body from
invasion by foreign material such as bacteria, viruses, and fungi. It also removes worn-out or
damaged cells from the body.
A. Organs of the Immune System
The immune system includes lymph (circulating fluid that contains a type of white blood
cell called lymphocytes) and lymph nodes (interspersed oval capsule structures) through
which lymph circulates (see Figure 6.1). Various types of lymphocytes include T-cells, B-
cells, and natural killer (NK) cells. The thymus, tonsils, and spleen are also involved with
the production, maturation, or differentiation of the various types of lymphocytes.
B. Function of the Immune System
The immune system is the body’s defense against foreign invaders, and it must be
virtually 100% effective in destroying invaders (see Figure 6.2).
1. Nonspecific Immune System Responses
Phagocytosis (attack of foreign particles by granulocytes or macrophages) and
2. Specific Immune System Responses
Contact with invading microorganisms sensitizes T-cells, allowing the cytotoxic T-
3. Creating Immunity
Vaccination is the introduction of weakened or dead bacteria or viruses, thus creating
a specific immunity. Each virus requires such treatment, which makes this process
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II. Psychoneuroimmunology
Psychoneuroimmunology is the interdisciplinary field that focuses on the interactions
among behavior, the nervous system, the endocrine system, and the immune system.
A. The History of Psychoneuroimmunology
Until the 1960s, the immune system was thought to be independent of the nervous system
B. Research in Psychoneuroimmunology
Research in psychoneuroimmunology has attempted to reveal the interactions among
behavior, the nervous system, the endocrine system, and the immune system by
demonstrating that behavior can affect the immune system and that disease can result from
C. Physical Mechanisms of Influence
The link between behavior and depressed immune function must occur through some
physical mechanism, and research has examined both the action of the peripheral nervous
system during stress and neuroendocrine responses in the brain. The immune system also
signals the nervous system by way of cytokines. Stressed people behave differently, often
paying less attention to a healthy lifestyle. Thus, the interrelationship between nervous
system and immune system is complex, with many possibilities for mutual influence.
III. Does Stress Cause Disease?
A. The Diathesis-Stress Model
Why does stress affect some people, apparently causing them to get sick, while leaving
others unaffected? The diathesis-stress model offers a possible answer to this question. This
model suggests that some individuals are vulnerable to stress-related diseases because either
genetic weakness or biochemical imbalance inherently predisposes them to those diseases.
Whether inherited or acquired, the vulnerability to stress-related disease is relatively
permanent. For people with a strong predisposition to a disease, even a mild environmental
stressor may be sufficient to produce an illness episode.
B. Stress and Disease
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The link between stress and disease may come through effects to the nervous, immune, or
endocrine system. Indirect effects could include health threats that occur because of changes
in health-related behaviors related to stress. Some evidence exists concerning the link
between stress and a variety of physical and psychological problems.
1. Headaches
2. Infectious Disease
Early research indicated that stress was a weak factor in developing infectious
disease. However, later research by Sheldon Cohen and his associates intentionally
3. Cardiovascular Disease
Cardiovascular disease has a number of risk factors, some of which are related to
stress. For people with preexisting CVD, stress increases their risk of heart attack. A
large international study identified several psychological stressors as a risk for heart
attack; these risks included workplace and home stress, financial problems, major life
events, depression, and external locus of control.
4. Ulcers
Despite the widespread belief that stress causes ulcers, the underlying cause of most
5. Other Physical Disorders
Stress may be implicated in the development and management of Type 1 and Type 2
diabetes mellitus and rheumatoid arthritis. Stress experienced by pregnant women
C. Stress and Psychological Disorders
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1. Depression
Stress is one factor that makes people vulnerable to depression, but effective coping
protects against depression. The tendency to ruminate over negative events increases the
risk for depression, and genetic vulnerability is also a risk. Chronic workplace stress,
poor health, and caregiving are stressors that increase the risk for depression. The route
2. Anxiety Disorders
Anxiety disorders include panic attack, agoraphobia, generalized anxiety, obsessive-
compulsive disorders, and posttraumatic stress disorder (PTSD). PTSD is, by
definition, related to stress, and PTSD also produces suppression of the immune system.
Stress is less clearly related to the other anxiety disorders, partly because the overlap
between anxiety and depression makes it difficult to disentangle these two problems.
Exploring Health on the Web
The vast amount of information about stress on the Internet also includes diseases related to
stress. Websites listed in Chapters 5 and 8 may also be of interest.
Suggested Activities
Personal Health Profile — Recording Stress
For Chapter 5 we suggested asking your students to fill out a life events scale, such as
The Undergraduate Stress Questionnaire. For this chapter we suggest that your students begin
keeping a stress diary or daily log as part of their Personal Health Profile. Such a procedure
allows students to record daily stresses and to rate them on a scale of 1 to 10, with 1 being least
stressful and 10 being most severe. This activity enables each student to profile his or her own
stresses, and to look for external events, such as examinations or interpersonal problems, to
determine any possible pattern. Also, your students may discover personal variables that tend to
magnify stressful events. This diary will add useful information that will give the students some
clues regarding changes they may wish to make in their lifestyle.
Stress and Health Habits
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Chapter 6 presented a great deal of information about how stress might affect health
through its influence on the immune system. Another possible link between stress and disease
that Chapter 6 also mentions is the relationship between stress and health habits. When people
are stressed, their behavior changes, and they often indulge in unhealthy behaviors that they
might not if they felt better. Also, stress may reduce people’s motivations to adhere to healthy
habits, such as a healthy diet or an exercise regimen. Therefore, stress can reduce people’s
adherence to a healthy behaviors in two ways—adding unhealthy behaviors and failing to enact
healthy ones.
Encourage your students to explore this stress-illness link by examining their own health
habits when they are under stress. Do they become more likely to overeat, drink, smoke, or use
drugs as ways to manage stress and feel better? If so, prompt them to formulate some alternative
coping strategies that present less risk to their health.
Debate: Does Stress Cause Disease?
Stress and Illness in Your Class
Crandall and his associates determined that scores on the USQ were correlated with
health care visits. Determine if this relationship holds for the students in your class. Based on
your students’ scores for the USQ, determine the relationship between scores and recent health
care visits or problems. This procedure may include gathering USQ scores and number of health
problems within the past month and computing a correlation.
Stress and Illness on Campus
You can examine the relationship between stress and illness on your campus by charting
the number of times students seek medical care during the school year. If your school has a
campus health center, hospital, or student infirmary, you may be able to obtain records
concerning number of visits during each week of the year. If you can find out how many students
sought health care, then your students can chart the number of visits per week and examine the
school’s calendar to determine possible stressors during the preceding weeks to determine any
relationship.
You will not need any personal information about the patients who sought health care, so
confidentiality should not be an issue in obtaining this information. The ideal data would consist
of the number of visits per week by diagnosis so that your students can eliminate patients who
sought care for problems that have no relationship to immune system function.
Sociocultural Factors, Stress, and Health
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Post-Traumatic Stress Disorder
Have students discuss Post-Traumatic Stress Disorder (PTSD) from a variety of
viewpoints: the diathesis-stress model; a biopsychosocial perspective; a cultural or social
phenomenon only; or a psychoneuroimmunology explanation. What research supports each
viewpoint? Can we, at this time, definitively choose one model that best explains PTSD?
Video Recommendations
From Films for the Humanities & Sciences:
Your Immune System (2003) presents the function of the immune system and the problems that
may affect it.
Seriously Stressed (2006) explores the stress produced by modern society, including symptoms
of chronic stress and potential negative effects by featuring case studies of individuals and the
stresses in their lives.
Videos from the Web:
Multiple Choice Questions
Understanding Stress, Immunity, and Disease
1. The main function of the immune system is to
a. manufacture white blood cells.
b. manufacture red blood cells.
c. protect internal organs.
d. defend against foreign invaders.
2. Leukocytes are
a. white blood cells.
b. red blood cells.
c. platelets.
d. capillaries.
3. A function of lymph nodes is to
a. secrete thymosin.
b. serve as a holding station for red blood cells.
c. cleanse lymph of foreign debris.
d. all of these.
4. Which of these is NOT an organ of the immune system?
a. liver
b. spleen
c. tonsils
d. thymus
5. Which of the following performs specific immune responses?
a. phagocytosis
b. T-cells and B-cells
c. granulocytes
d. macrophages
6. Nonspecific immune system response
a. provides the first line of defense against foreign substances in the body.
b. occurs in a nonspecific order.
c. has the ability to create a type of memory that confers immunity.
d. protects against specific immune responses that threaten the body.
7. Immunity occurs when
a. memory lymphocytes persist after initial exposure to a virus.
b. antigens build up.
c. antibody levels fall.
d. interferon is transferred from one person to another.
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8. The development of immunity depends on the creation of
a. leukocytes.
b. natural killer cells.
c. antigens.
d. antibodies.
9. HIV is caused by
a. a viral infection.
b. a bacterial infection.
c. exposure to a cancer-causing agent.
d. homosexuality.
10. Suppression of the immune system
a. is a desirable action following most major surgery.
b. will stop infection.
c. leaves the body vulnerable to infection.
d. never occurs naturally, but can be induced with drugs.
11. Allergic reactions are
a. a result of digestive system dysfunction.
b. an abnormal immune system reaction to a foreign substance.
c. caused by viruses.
d. more common in people whose immune systems are not fully functional at birth.
12. Autoimmune disease occurs when
a. the immune system loses its effectiveness.
b. T-cells are reduced by 90%.
c. malignant cells proliferate, producing a demand for numerous immune system
responses.
d. the immune system attacks body cells rather than invaders.
13. Increasing the efficiency of the immune system would be a problem for whom?
a. people with cancer
b. people with AIDS
c. people who have received transplanted organs
d. people with bacterial diseases
14. Enhancing immune system function would be useful in the treatment of
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a. allergies.
b. organ transplant patients.
c. AIDS.
d. cardiovascular disease.
15. The two general, or nonspecific, mechanisms that foreign substances “face” are:
a. phagocytosis and inflammation
b. phagocytosis and mucous membranes
c. inflammation and mucous membranes
d. the spleen and inflammation
16. Substances that evoke the production of one or more antibodies are called _____.
a. antigens
b. vaccination
c. phagocytes
d. lymph nodes
17. __________ enable the immune system to have a rapid response when the foreign
invader reappears.
a. Antigens
b. Phagocytes
c. Memory lymphocytes
d. Leukocytes
18. The highest concentration of the virus for HIV is found in ______.
a. saliva and in the blood.
b. saliva and in semen.
c. blood and in semen.
d. saliva, in the blood, and in semen.
19. The discipline concerned specifically with the interactions among behavior, the endocrine
system, the immune system, and the nervous system is
a. transactional analysis.
b. behavioral medicine.
c. health psychology.
d. psychoneuroimmunology.
20. Ader and Cohen demonstrated that
a. the immune system could be conditioned.
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b. the immune system was independent of the nervous system.
c. the adrenomedullary response was independent of the adrenocortical response.
d. allostasis does not apply to the General Adaptation Syndrome.
21. What relationship is the basis of psychoneuroimmunology?
a. Endocrine function affects behavior, and behavior can either raise or lower
immune system function.
b. Behavior affects the immune system, and immune system function affects health.
c. Health and disease affect immune system function, and behavior affects the
nervous system as well as the endocrine system.
d. The action of the immune system is independent of behavior, and the endocrine
and nervous systems are less dependent than has been previously assumed.
22. Research in the field of psychoneuroimmunology has found evidence that immune
function can be decreased by
a. exam stress.
b. caring for someone with Alzheimer’s disease.
c. relationship conflict.
d. all of these.
23. Research by Kiecolt-Glaser and her colleagues has shown that Alzheimer’s caregivers,
compared with other people of the same age and gender,
a. had poorer psychological and physical health.
b. had lowered immune system function.
c. more quickly recovered their own health after the death of the Alzheimer’s
patient.
d. both a and b are correct.
24. Recent research that presented photographs of infectious disease to participants found
that, after viewing this pictures, participants
a. sneezed and felt nauseous.
b. reported more trips to the health center that semester.
c. had increased production of proinflammatory cytokines.
d. all of the above.
25. Marital conflict is associated with __________
a. faster response times to dangerous stimuli.
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b. slower response times to dangerous stimuli.
c. faster wound healing.
d. slower wound healing.
26. __________ experience poorer psychological and physical health, longer healing times
for wounds, and lowered immune functioning.
a. First-time mothers
b. First-time fathers
c. Alzheimer’s caregivers
d. The elderly
27. Which of the following individuals would be most likely to have decreased immune
system functioning?
a. Anna, who is taking her first exam in psychology this week
b. Nathan, who has an hour commute to school each week
c. Marissa, who just had her first child
d. Claude, who is unemployed and lives in a high-crime neighborhood
28. Antoni and colleagues (2009) designed a cognitive behavioral stress management
intervention for women with breast cancer, and over a 6-month period, improvements in
______ were found.
a. depression levels
b. anxiety levels
c. immune measures
d. cortisol
29. These chemicals secreted by the immune system signal the nervous system:
a. cytokines
b. leukocytes
c. phagocytes
d. antigens
30. In order for stress to cause illness, stress must affect physiological processes that produce
illness. The most likely candidate for a mechanism is the _____ system.
a. immune
b. nervous
c. endocrine
d. digestive
31. Direct effects of stress on the immune system occur through ______, and indirect effects
can occur through ______.
a. the cardiovascular system . . . autonomic nervous system activation effects
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b. the sympathetic nervous system . . . parasympathetic nervous system suppression
c. connections between the immune and nervous systems . . . secretion of hormones
d. the adrenal medulla . . . activation of the pituitary gland and releasing factors
32. One route through which stress may affect the immune system is through
a. lowered epinephrine levels.
b. elevated cortisol levels.
c. reverse peristalsis.
d. any of these.
33. With regard to stress and illness, which of these statements is true?
a. Stress is a better predictor of heart disease than it is of hypertension.
b. Most people at risk from stressful experience will not develop a disease.
c. Stress is a better predictor of heart disease than cigarette smoking.
d. Both a and c are correct.
34. Stress may relate to disease because people under stress may
a. abuse alcohol.
b. eat unhealthy foods.
c. use illicit drugs.
d. do any or all of these.
35. The diathesis-stress model hypothesizes that
a. stress is most likely to produce illness in a healthy person.
b. stress and psychological functioning interact to produce better health.
c. some people are more inherently vulnerable to the effects of stress.
d. some people learn to cope with stress but not with stressful life events.
36. With regard to stress and disease,
a. executives are more likely than middle-level managers to develop stress-related
diseases.
b. stress can affect the development of disease directly through the immune system
or indirectly through unhealthy behaviors.
c. stress is more likely to result in psychological disorders than in physical diseases.
d. both a and c are correct.
37. The diathesis-stress model assumes that to become ill
a. a person must have a relatively permanent predisposition to the illness.
b. a person must experience some sort of stress.