The Bodys Response to Stress

How our bodies react to stress has been studied for decades. Stress begins with a stimulus in our environment that we interpret as threatening. It can involve hearing, seeing, touching, or all of these senses. The brain integrates these sensations, and as a result, the amygdala, hypothalamus, and pituitary gland are activated. The amygdala and hypothalamus are parts of the brain associated with fear, stress, and the integration of bodily functions. The pituitary gland, which is controlled by the hypothalamus, is located just beneath the brain and releases hormones needed by the body. As part of the stress response, ACTH, a hormone released from the pituitary gland activates the adrenal glands, which in turn release the stress hormones, epineph-rine and cortisol (see Figure 9-1). These hormones act throughout the body to prepare us for responsive action. Epinephrine increases heart rate and blood pressure to help the body meet the new demands. Cortisol increases blood sugar (glucose) to provide more fuel for the energy needed to deal with the stressor, and it does this by promoting the synthesis of glucose and by assisting in the metabolism of fat, protein, and carbohydrates that produce additional glucose. Chronic stress can affect many organ systems and leave us depressed, with aches and pains, nausea, dizziness, rapid heartbeat, and exhaustion. Stress can also suppress our immune system, leaving us with a greater risk for infection.

There are also emotional and mental responses to stress. Normally the frontal cortex, a highly evolved part of the brain, regulates reality testing, guides attention and thought, inhibits inappropriate actions, and regulates emotion. But under stress, other brain regions strongly come into play. The amygdala activates stress pathways in the hypothalamus and brainstem, which results in a loss of prefrontal cortex regulation and disposes us toward habitual responding rather than more cognitively controlled actions. So, stress causes a switch from reflective and modulated responses to emotionally driven reflexive responses.

Stressors can be personal, and what stresses one person might not stress another. There are many kinds of stressors. Environmental stressors include a natural disaster such as an earthquake, the 9/11 terrorist attack, or even such things as uncontrollable loud sounds or bright lights. Life changes such as divorce, job loss, or deaths in the family can be serious stressors. The workplace can be stressful, and this is often related to how much control an employee has over his or her job and its conditions. Also, daily events such as a fender bender, loss of house keys, or theft of a purse or wallet can be very troublesome. Because of the dangers of stress and cumulative layers of stress, we must develop styles and support systems to help us handle it. Stress busters include play and exercise, meditation, improved diet, and medical care.

Figure 9-1 The body's stress response. When someone is stressed, the brain's stress pathways are activated such that the hypothalamus, found in the base of the brain, sends a chemical signal, CRH, to the pituitary gland, which sends another chemical signal, ACTH, to the adrenal glands (found near the kidneys). The adrenals secrete cortisol, which is the well known "stress hormone" into the blood. Cortisol then stimulates a metabolic response and circulates back to the brain to stop or regulate the release of chemicals from the hypothalamus and pituitary. This regulation is important so that this stress response is not a "runaway" process. Many addicts are hypersensitive to stress. (From http://being.publicradio.org/programs/stress/particulars.shtml and Roberto Osti, with permission.)

Figure 9-1 The body's stress response. When someone is stressed, the brain's stress pathways are activated such that the hypothalamus, found in the base of the brain, sends a chemical signal, CRH, to the pituitary gland, which sends another chemical signal, ACTH, to the adrenal glands (found near the kidneys). The adrenals secrete cortisol, which is the well known "stress hormone" into the blood. Cortisol then stimulates a metabolic response and circulates back to the brain to stop or regulate the release of chemicals from the hypothalamus and pituitary. This regulation is important so that this stress response is not a "runaway" process. Many addicts are hypersensitive to stress. (From http://being.publicradio.org/programs/stress/particulars.shtml and Roberto Osti, with permission.)

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