Causes and Effect of Stress

Introduction

The stress response refers to how the different physiological systems of the body respond to a stressor. A stressor can be either physical, such as the demands imposed on the body by the physical exertion of exercise, or psychological or mental, such as the stress we may experience in our day-to-day lives. (Grant, Compas, Thurm, McMahon and Gipson, 412-425) These include a student taking an exam, meeting work deadlines, and being stuck in traffic; even winning a lottery ticket can be experienced by some people as a stressor. It is important to keep in mind that not all people experience the same event as stressful. That is, it is more our reaction that determines whether it is stressful rather than any necessarily inherent nature of the event or experience itself.

The stress response as we know it is rooted in an ancient part of our body's physiological responses (Grinker and Spiegel, 24-32) known as the fight-or-flight response. In this sense, the response first evolved as a mechanism for survival. It is only when this same response is turned on chronically that it can exert deleterious effects on our physical and mental health.

This section reviews how the major physiological systems of the body are affected by acute and chronic stress.

Nervous System

The brain regulates body functions at all times. The hypothalamic-pituitary-adrenal axis together with the autonomic nervous system controls the stress response (Sapolsky, 57-66). The hypothalamic-pituitary-adrenal axis consists of the hypothalamus (base of the brain), pituitary gland (below the hypothalamus), and adrenal gland (over the kidneys). The hypothalamus releases corticotropin-releasing factor, which stimulates the pituitary gland to release adrenocorticotropic hormone. Adrenocorticotropic hormone in turn stimulates the adrenal gland to release steroids called glucocorticoids (e.g., cortisol). Cortisol acts as a key regulator of the body's stress response (Grinker and Spiegel, 24-32). There is a negative feedback system that regulates cortisol levels. When cortisol levels rise, a negative feedback signal to the hypothalamus inhibits further release of corticotropin-releasing hormone. This essential ability of the negative feedback system to limit the production of cortisol is impaired in individuals with a history of chronic emotional/physical stress. Excessive and sustained cortisol secretion has been linked to a host of diseases such as hypertension, depression, and osteoporosis.

The autonomic nervous system is the other part of the nervous system that controls the stress response. The autonomic nervous system consists of two components, a sympathetic nervous system and a parasympathetic nervous system. The two systems work in opposition whereby the activation of one is accompanied by the suppression of the other. The sympathetic nervous system is activated during stress and mediates the fight-or-flight response in which two chemical messengers, epinephrine and norepinephrine, are released from the nerve endings and from the adrenal glands. (Sapolsky, 57-66)

What happens to our different body systems during stress is mainly, (Grinker and Spiegel, 24-32) but not exclusively, regulated by epinephrine, norepinephrine, and glucocorticoids. It is now known that chronic stress may be a precipitating or at least an aggravating factor in many diseases ...