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Protocols for measurements that actually cause stress have little value; is one

measuring the individual’s current stress or creating the stress that is being quan-

tified? One example is the use of venipuncture to obtain blood samples.

Venipuncture stimulates a marked increase in sympathetic nervous system activity
and leads to an increase in plasma catecholamine (epinephrine and norepinephrine)

levels by over 50% (Carruthers et al. 1970 ; Brown 2007 ).

The most direct measures of stress would somehow tap into the brain activities

involved with stress appraisal. This is not possible for studies that involve people

doing normal activities. The next most direct measures would examine the markers

of brain activity that“spill over”into other parts of the body: for instance, the

presence of catecholamines in the blood (Esler 1993 ; Brown 2007 ). Again, the

problem of obtaining adequate samples of blood without actually being a cause of

stress impedes the ability to use these direct measures. Human biologists have

instead used more indirect measures of stress appraisal, such as urinary cate-

cholamines, urinary or salivary cortisol, cortisol deposited in hair, and salivary

alpha-amylase—an indicator of sympathetic nervous system activity (Ice and James

Cortisol

Epinephrine

Norepinephrine

Stressor

(stimulus)

Cognitive Brain

Centers

Amygdala

Sympathetic

Nervous System

and Adrenal

Medulla

Brain/

Spinal Cord

Stress induced

analgesia

Circulatory

System

Increased heart rate,

stroke volume, blood

pressure

Increased ventilation, Lungs

Bronchial dilation

Vasodilation Muscle

Glycogenolysis, Liver

gluconeogenesis

Pituitary Adrenal

Cortical System

Immune

System

Inhibition of

T cells; reduced

inflammation

Sweat

Glands

Increased sweat

production

Hypothalamus

Fig. 7.2 A simplified diagram of the physiological stress response (after Brown 1981 )

122 D.E. Brown