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- Stress facts
- What is stress?
- A brief history of stress
- What are the signs and symptoms of poorly managed stress?
- Who is most vulnerable to stress? What are the risk factors for stress?
- Teen stress
- What is the healthy response to stress?
- How does the response to stress work?
- What is the role of the hypothalamus-pituitary-adrenal (HPA) axis (grouping) in stress?
- What is the role of the locus coeruleus in stress?
- How do the connections in the brain work in stress?
- What do we know about using (activating) and overusing our internal systems that respond to stress?
- What are the effects of stress on medical and psychological conditions?
- Conclusions about the effects of stress
- What can people do for stress management? What are home remedies to combat stress symptoms?
- What's in the future for stress?
What is the healthy response to stress?
A key aspect of a healthy adaptational response to stress is the time course. Responses must be initiated rapidly, maintained for a proper amount of time, and then turned off to ensure an optimal result. An over-response to stress or the failure to shut off a stress response can have negative biological and mental-health consequences for an individual. Healthy human responses to stress involve three components:
- The brain handles (mediates) the immediate response. This response signals the adrenal medulla to release epinephrine and norepinephrine.
- The hypothalamus (a central area in the brain) and the pituitary gland initiate (trigger) the slower maintenance response by signaling the adrenal cortex to release cortisol and other hormones.
- Many neural (nerve) circuits are involved in the behavioral response. This response increases arousal (alertness, heightened awareness), focuses attention, inhibits feeding and reproductive behavior, reduces pain perception, and redirects behavior.
The combined results of these three components of the stress response maintain the internal balance (homeostasis) and optimize energy production and utilization. They also gear up the organism for a quick reaction through the sympathetic nervous system (SNS). The SNS operates by increasing the heart rate, increasing blood pressure, redirecting blood flow to the heart, muscles, and brain and away from the gastrointestinal tract, and releasing fuel (glucose and fatty acids) to help fight or flee the danger.
How does the response to stress work?
While the complete story is not fully known, scientists understand much about how the response to stress works. The two main systems involved are the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS). (These systems are described later.) Triggered (activated) primarily by an area in the brain stem (lowest part of brain) called the locus coeruleus, the SNS results in the secretion of epinephrine and norepinephrine. The following are the five most important concepts to remember about these two systems:
- They are governed by a feedback loop to regulate their response. (In a feedback loop, increased amounts of a
substance -- forexample, a hormone -- inhibitthe release of more of that substance, while decreased amounts of the substance stimulate the release of more of that substance.)
- They interact with each other.
- They influence other brain systems and functions.
- Genetic (inherited) variability affects the responses of both systems. (That is, depending on their genes, different people can respond differently to similar stresses.)
- Prolonged or overwhelming responses of these systems can be harmful to an individual.