What Is Stress?
Stress is a feeling that's created when we react to particular events. It's the body's way of rising to a challenge and preparing to meet a tough situation with focus, strength, stamina, and heightened alertness.
The events that provoke stress are called stressors, and they cover a whole range of situations — everything from outright physical danger to making a class presentation or taking a semester's worth of your toughest subject.
The human body responds to stressors by activating the nervous system and specific hormones. The hypothalamus signals the adrenal glands to produce more of the hormones adrenaline and cortisol and release them into the bloodstream. These hormones speed up heart rate, breathing rate, blood pressure, and metabolism. Blood vessels open wider to let more blood flow to large muscle groups, putting our muscles on alert. Pupils dilate to improve vision. The liver releases some of its stored glucose to increase the body's energy. And sweat is produced to cool the body. All of these physical changes prepare a person to react quickly and effectively to handle the pressure of the moment.
This natural reaction is known as the stress response. Working properly, the body's stress response enhances a person's ability to perform well under pressure. But the stress response can also cause problems when it overreacts or fails to turn off and reset itself properly.
Good Stress and Bad Stress
The stress response (also called the fight or flight response) is critical during emergency situations, such as when a driver has to slam on the brakes to avoid an accident. It can also be activated in a milder form at a time when the pressure's on but there's no actual danger — like stepping up to take the foul shot that could win the game, getting ready to go to a big dance, or sitting down for a final exam. A little of this stress can help keep you on your toes, ready to rise to a challenge. And the nervous system quickly returns to its normal state, standing by to respond again when needed.
But stress doesn't always happen in response to things that are immediate or that are over quickly. Ongoing or long-term events, like coping with a divorce or moving to a new neighborhood or school, can cause stress, too.
Long-term stressful situations can produce a lasting, low-level stress that's hard on people. The nervous system senses continued pressure and may remain slightly activated and continue to pump out extra stress hormones over an extended period. This can wear out the body's reserves, leave a person feeling depleted or overwhelmed, weaken the body's immune system, and cause other problems.
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 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.
What is the role of the hypothalamus-pituitary-adrenal (HPA) axis (grouping) in stress?
The HPA axis is a grouping of responses to stress by the brain and the pituitary and adrenal glands. First, the hypothalamus (a central part of the brain) releases a compound called corticotrophin releasing factor (CRF), which was discovered in 1981. The CRF then travels to the pituitary gland, where it triggers the release of a hormone, adrenocorticotrophic hormone (ACTH). ACTH is released into the bloodstream and causes the cortex of the adrenal gland to release the stress hormones, particularly cortisol, which is a corticosteroid hormone. Cortisol increases the availability of the body's fuel supply (carbohydrate, fat, and glucose), which is needed to respond to stress. However, if cortisol levels remain elevated for too long, then muscle breaks down, there is a decreased inflammatory response, and suppression of the immune (defense) system occurs.
Because they suppress the immune system, corticosteroids in measured doses are used to treat many illnesses that are characterized by inflammation or an overactive immune system, such as asthma and inflammatory bowel disease. For the same reason, they are used to help reduce the chances that our body will immunologically reject a transplanted organ. Corticosteroids also can cause fluid retention and high blood pressure. Therefore, it is critical that the response to corticosteroids be carefully controlled (modulated). This control usually is accomplished by a feedback mechanism in which increased cortisol levels feeding back to the hypothalamus and pituitary turn off production of ACTH. In addition, extremely high levels of cortisol can cause mental changes, including depression and psychosis, which disappear when the levels return to normal.
BY-RV/07-25,27,28
Stress is a feeling that's created when we react to particular events. It's the body's way of rising to a challenge and preparing to meet a tough situation with focus, strength, stamina, and heightened alertness.
The events that provoke stress are called stressors, and they cover a whole range of situations — everything from outright physical danger to making a class presentation or taking a semester's worth of your toughest subject.
The human body responds to stressors by activating the nervous system and specific hormones. The hypothalamus signals the adrenal glands to produce more of the hormones adrenaline and cortisol and release them into the bloodstream. These hormones speed up heart rate, breathing rate, blood pressure, and metabolism. Blood vessels open wider to let more blood flow to large muscle groups, putting our muscles on alert. Pupils dilate to improve vision. The liver releases some of its stored glucose to increase the body's energy. And sweat is produced to cool the body. All of these physical changes prepare a person to react quickly and effectively to handle the pressure of the moment.
This natural reaction is known as the stress response. Working properly, the body's stress response enhances a person's ability to perform well under pressure. But the stress response can also cause problems when it overreacts or fails to turn off and reset itself properly.
Good Stress and Bad Stress
The stress response (also called the fight or flight response) is critical during emergency situations, such as when a driver has to slam on the brakes to avoid an accident. It can also be activated in a milder form at a time when the pressure's on but there's no actual danger — like stepping up to take the foul shot that could win the game, getting ready to go to a big dance, or sitting down for a final exam. A little of this stress can help keep you on your toes, ready to rise to a challenge. And the nervous system quickly returns to its normal state, standing by to respond again when needed.
But stress doesn't always happen in response to things that are immediate or that are over quickly. Ongoing or long-term events, like coping with a divorce or moving to a new neighborhood or school, can cause stress, too.
Long-term stressful situations can produce a lasting, low-level stress that's hard on people. The nervous system senses continued pressure and may remain slightly activated and continue to pump out extra stress hormones over an extended period. This can wear out the body's reserves, leave a person feeling depleted or overwhelmed, weaken the body's immune system, and cause other problems.
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 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.
What is the role of the hypothalamus-pituitary-adrenal (HPA) axis (grouping) in stress?
The HPA axis is a grouping of responses to stress by the brain and the pituitary and adrenal glands. First, the hypothalamus (a central part of the brain) releases a compound called corticotrophin releasing factor (CRF), which was discovered in 1981. The CRF then travels to the pituitary gland, where it triggers the release of a hormone, adrenocorticotrophic hormone (ACTH). ACTH is released into the bloodstream and causes the cortex of the adrenal gland to release the stress hormones, particularly cortisol, which is a corticosteroid hormone. Cortisol increases the availability of the body's fuel supply (carbohydrate, fat, and glucose), which is needed to respond to stress. However, if cortisol levels remain elevated for too long, then muscle breaks down, there is a decreased inflammatory response, and suppression of the immune (defense) system occurs.
Because they suppress the immune system, corticosteroids in measured doses are used to treat many illnesses that are characterized by inflammation or an overactive immune system, such as asthma and inflammatory bowel disease. For the same reason, they are used to help reduce the chances that our body will immunologically reject a transplanted organ. Corticosteroids also can cause fluid retention and high blood pressure. Therefore, it is critical that the response to corticosteroids be carefully controlled (modulated). This control usually is accomplished by a feedback mechanism in which increased cortisol levels feeding back to the hypothalamus and pituitary turn off production of ACTH. In addition, extremely high levels of cortisol can cause mental changes, including depression and psychosis, which disappear when the levels return to normal.
BY-RV/07-25,27,28
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