Health, Illness, and Optimal Aging- Biological and Psychological Perspectives
oPituitary releases adrenocorticotropin hormone (ACTH) into blood stream
oACTH stimulates the cortex of adrenal glands to release corticosteroids
-Cannon argued that this fight/flight reaction, although adaptive in the short run, could
have very harmful effects if prolonged.
-Hans Selye expanded on Cannon’s conceptions in two ways. First, he noticed that
corticosteroids, which are released by the adrenal cortex (or top layer of the adrenal
glands), are also elevated in response to a wide variety of stressors.
-Glucocorticoids are fat-soluble molecules, which enables them to cross cell membranes in
every organ system in the body. Thus, they have a wide range of effects. Thus, stress can
affect the functioning of nearly every organ system in the body, either through SNS or
-Second, Selye expanded Cannon’s dualistic processes (SNS vs. PNS activation) by
describing three stages in reaction to stress.
oThe alarm stage is similar to Cannon’s fight/flight reaction but involves the
adrenal glands as well as SNS activation.
oThe second stage was adaptation- in which there is a return to physiological
homeostasis (due to PNS activation)
oThird stage, exhaustion, the organism may fall ill or die if the stress continues
[hormones becoming depleted]
-Both Cannon and Seyle argued that there are general responses to stress, but it is now
widely recognized that there are individual differences in stress reactions.
-From a psychosocial perspective, studies investigating the effect of stress on sympathetic
arousal, including heart rate, respiratory rate, and galvanic skin response (a measure of
the degree to which the electrical conductance of the skin is affected by sweating)
consistently found individual differences in the patterning of sympathetic arousal.
-In addition, it is now recognized that activation of the HPA axis is an attempt to buffer the
rather damaging influence of prolonged SNS activation.
-SNS activates immune system responses, encouraging inflammation; HPA activation
suppresses the immune/inflammatory response
-In addition, we now know that most, if not all, of the endocrine hormones are affected by
stress, increasing or decreasing in fairly complex temporal patterns.
-In general, stress activates those hormones that increase metabolic functioning and
suppresses those involved in long-term growth and maintenance.
-The recognition of broader endocrine responses to stress has led to an argument for a
third stress pathway, through oxytocin.
-Oxytocin is a hormone that is very important in reproductive activities such as breast-