Stress: Brain and Body

Sam Yarmis

Every day, you probably face a number of stressors: a paper to write, an exam to study for, a difficult situation at work or at home. So you are no stranger to the headaches, sweaty hands, and queasy stomach feelings associated with stress. However, the body’s response to stress, like many other emotional and physical responses, is governed by its innate drive to protect itself in the face of an external threat.

Hans Selye, an endocrinologist instrumental in defining and researching stress, defined the general adaptation syndrome (abbreviated GAS), which describes how the body reacts to a stressor. The first stage of GAS is alarm; the body produces adrenaline, thus activating the fight-or-flight response, which is the immediate reaction to a new stressor. This pathway involves many physiological and behavioral changes in response to high-pressure situations, preparing the body to either stay and fight or run away from the stressor.

Such acute-stress situations activate the hypothalamus, a region of the brain just above the brain stem. The hypothalamus, which links the nervous system to the endocrine system, releases a variety of hormones; these hormones regulate body temperature, hunger, thirst, and the release of hormones from other glands, most importantly the pituitary gland. Given the breadth of action of this organ, it’s no wonder that the hypothalamus can trigger the numerous effects of the fight-or-flight response.

Also important in acute stress response is the adrenal gland, which is controlled by the liver. The adrenal gland releases the hormone and neurotransmitter adrenaline, causing an increased heartbeat, shallow breathing, and dilated pupils. The gland also releases the hormone cortisol and other similar substances, called corticoids, which increase blood pressure and blood sugar by stimulating the liver to release glucose. If the difficulty is dealt with quickly, the body returns to homeostasis, or equilibrium, following fight-or-flight.

However, if someone is in a constantly taxing situation, the second stage of GAS, resistance, begins, which can have much more detrimental effects on the body. In chronically stressful situations, there is no opportunity for the body to return to homeostasis and turn off the pathways initialized by the fight-or-flight response. Some symptoms of chronic stress in the second stage of GAS include teeth grinding, dry mouth, chest pain, and hypertension, or high blood pressure, which can lead to heart disease or cardiac arrest. Chronic stress is also linked with an increased risk of Alzheimer’s disease, although the correlation cannot clearly be explained yet.

Ultimately, chronic stress leads to the third and final stage of GAS, exhaustion. In this stage, the body’s resources are drained. In these situations, the liver is bypassed and the hormones of the adrenal gland cannot be controlled. The overproduction of the adrenal gland hormones leads to a weakened immune system and, due to its prolonged secretion, an increased resistance to adrenaline. This excess of adrenaline increases the output of stomach acid, which can lead to stomach ulcers and heartburn. If this stage is prolonged, the body may sustain long-term damage due to the depleted immune system and increased stomach acid.

Whenever possible, chronically stressful situations should be eliminated. One common technique to do this is to identify and list your stressors. Then, decide which can be eliminated, such as extra, unnecessary tasks at work, at home, or in your community. For stressors that cannot be removed, such as a difficult situation at work, there are a variety of relaxation techniques to manage all three stages of GAS. Dozens of studies have proved that exercise releases endorphins, which help relieve stress and encourage positive thinking; experts recommend exercising for at least 30 minutes per day, three days a week. Deep breathing, meditation, and yoga have all been shown to help increase blood flow; these techniques help clear the mind and allow the user to find a measure of calmness and quiet in an otherwise hectic, stressful day. Mindfulness-based stress reduction (MBSR) is another stress-relief technique growing in popularity. People can enroll in MBSR classes, often offered at university hospitals, which are designed to help them learn to cope with chronic stress and pain.

Further information on stress and management techniques can be found at the American Institute of Stress ( and the National Institutes of Health (

Filed Under: Scientific Focus


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