Health Psychology, 2nd Edition

24 BIOLOGICAL BASES OF HEALTH AND ILLNESS

Stress

Adrenal

medulla

Adrenal

cortex

Pituitary

Adrenocorticotropic

hormone

Hypothalamus

ANS – Sympathetic

Division

Secretion of catecholamines

Increased cardiovascular response

Increased respiration

Increased perspiration

Increased blood flow to muscles

Increased muscle strength

Increased mental activity

Secretion of corticosteroids

Increased protein and fat

mobilization

Increased access to energy

storage

Decreased inflammation

FIGURE 2.3Stress response. Hypothalamic–pituitary–adrenal (HPA) axis response
system (dashed line) and the sympathetic adrenal medullary system (SAM)
response system (solid line).

The stress response and cardiovascular disease

In evolutionary terms, these stress response processes are adaptive and help ensure
survival. Nevertheless, they are only adaptive in so much as they are short-lived and
the body’s systems swiftly return to normal. Our ancestors may well have encountered
acute stressors in the form of wild animals while hunting, which made such ‘flight or
fight’ responses adaptive. The SAM and HPA response systems would prepare the body
appropriately. However, the stress of modern-day life rarely affords such infrequent,
acute, life-threatening stressful encounters. Instead, we are exposed to frequent daily
hassles as well as long-lasting, chronic stressors. As a result, the stress response system
is repeatedly activated and the cardiovascular system is potentially exposed to excessive
wear and tear. Over time, such repetitive activation may contribute to future ill health
by increasing cardiovascular disease risk (see Steptoe and Kivimaki, 2013).
This may result in the development of atherosclerosis, that is, the build-up of fatty
plaques in the inner lining of the blood vessels, which leads to the occlusion
(narrowing) of the arteries. The increase in blood pressure as a result of the repeated
activation of the SAM system may cause damage to the lining of the blood vessels,
thus allowing access to fatty acids and glucose. At the same time, activation of the HPA
axis leads to the release of cortisol, which increases the liberation of glucose from
glycogen stores. These processes taken together increase the likelihood that chronic
stress may lead to a build-up of plaque. The development of plaque can have serious
health consequences. The first symptom of a narrowing artery may be pain or cramps
at times when the blood flow cannot keep up with the body’s demands for oxygen.
During exercise, an individual may feel chest pain (angina) because of the lack of