Stress Illness and the Cardiovascular System

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A patrolling immune system cell sends out
an extension known as a pseudopod
(pronounced “SUE-doh-pod”) to engulf
and destroy a bacterial cell before alerting more defenders. These immune cells
are able to squeeze out of the bloodstream and enter organs, where they
destroy foreign cells.
THE FIRST LINE OF DEFENSE
Chapter 10 Health, Stress, and Coping
whereas others circulate in the bloodstream, entering tissues throughout the body.
Components of the immune system kill or inactivate foreign or harmful substances in
the body, such as viruses and bacteria (Simpson, Hurtley, & Marx, 2000). If our immune
systems are impaired, we are left more vulnerable to colds, mononucleosis, and many
other infectious diseases (Potter & Zautra, 1997). It is by disabling the immune system
that the human immunodeficiency virus (HIV) leads to AIDS and leaves the HIVinfected person defenseless against other infections or cancers. The immune system can
also become overactive, with devastating results. Many chronic, progressive diseases—
including arthritis, diabetes, and lupus erythematosus—are now recognized as autoimmune disorders. In these cases, cells of the immune system begin to attack and destroy
normal body cells (Oldenberg et al., 2000).
An important aspect of the human immune system is the action of the white
blood cells, called leukocytes (pronounced “LU-koh-sites”). These cells are formed in
the bone marrow and serve as the body’s mobile defense units. Leukocytes are called
to action when foreign substances are detected. Among the varied types of leukocytes are B-cells, which produce antibodies to fight foreign toxins; T-cells, which kill
other cells; and natural killer cells, which destroy a variety of foreign organisms and
are particularly important in fighting viruses and tumors. The brain can influence
the immune system indirectly by altering the secretion of adrenal hormones, such
as cortisol, that modify the circulation of T-cells and B-cells. The brain can also
influence the immune system directly by making connections with the immune
organs, such as the thymus, where T-cells and B-cells are stored (Felten et al., 1991;
Maier & Watkins, 2000).
The Immune System and Stress A wide variety of stressors can lead to sup-
pression of the immune system. The effects are especially strong in the elderly
(Penedo & Dahn, 2004), but they occur in everyone (Kiecolt-Glaser & Glaser, 2001;
Kiecolt-Glaser et al., 2002). One study showed that as first-year law students participated in class, took exams, and experienced other stressful aspects of law school, they
showed a decline in several measures of immune functioning (Segerstrom et al.,
1998). Similarly, decreases in natural killer cell activity have been observed in both
men and women following the deaths of their spouses (Irwin et al., 1987), and a variety of immune system impairments have been found in people suffering the effects
of prolonged marital conflict, divorce, or extended periods of caring for elderly relatives (Cacioppo et al., 1998; Kiecolt-Glaser et al., 2003, 2005; Vitaliano, Zhang, &
Scanlan, 2003).
The relationship between stress and the immune system can be critical to people who
are HIV-positive but do not yet have AIDS. Because their immune systems are already
fragile, further stress-related impairments could be life threatening. Research indicates
that psychological stressors are associated with the progression of HIV-related illnesses
(e.g., Antoni et al., 2000; Nott & Vedhara, 2000). Unfortunately, people with HIV (and
AIDS) face a particularly heavy load of immune-suppressing psychological stressors,
including uncertainty about the future. A lack of perceived control and resulting depression and anxiety can further magnify their stress responses (e.g., Sewell et al., 2000).
Stress, Illness, and the Cardiovascular System
Earlier we mentioned the role of the sympatho-adreno-medullary (SAM) system in
mobilizing the body’s defenses during times of threat. Because the SAM system is linked
to the cardiovascular system, its repeated activation in response to stressors has been
linked to the development of coronary heart disease (CHD), high blood pressure
(hypertension), and stroke (Krantz & McCeney, 2002). The link appears especially
strong in people who display strong physical reactions to stressors (Andre-Petersson
et al., 2001; Ming et al., 2004; Treiber et al., 2001). For example, among healthy young
adult research participants, those whose blood pressure rose most dramatically in
response to a mild stressor or a series of stressors were the ones most likely to develop