What is stress?
Stress is simply a fact of nature -- forces from the inside or outside world affecting the individual. The individual responds to stress in ways that affect the individual as well as their environment. Because of the overabundance of stress in our modern lives, we usually think of stress as a negative experience, but from a biological point of view, stress can be a neutral, negative, or positive experience.
In general, stress is related to both external and internal factors. External factors include the physical environment, including your job, your relationships with others, your home, and all the situations, challenges, difficulties, and expectations you're confronted with on a daily basis. Internal factors determine your body's ability to respond to, and deal with, the external stress-inducing factors. Internal factors which influence your ability to handle stress include your nutritional status, overall health and fitness levels, emotional well-being, and the amount of sleep and rest you get.
Stress has driven evolutionary change (the development and natural selection of species over time). Thus, the species that adapted best to the causes of stress (stressors) have survived and evolved into the plant and animal kingdoms we now observe.
Man is the most adaptive creature on the planet because of the evolution of the human brain, especially the part called the neo-cortex. This adaptability is largely due to the changes and stressors that we have faced and mastered. Therefore, we, unlike other animals, can live in any climate or ecosystem, at various altitudes, and avoid the danger of predators. Moreover, most recently, we have learned to live in the air, under the sea, and even in space, where no living creatures that we know of have ever survived.
A brief history of stress
A key to the understanding of the negative aspects of stress is the concept of milieu interieur (the internal environment of the body), which was first advanced by the French physiologist Claude Bernard. In this concept, he described the principles of dynamic equilibrium. In dynamic equilibrium, constancy, a steady state (situation) in the internal bodily environment, is essential to survival. Therefore, external changes in the environment or external forces that change the internal balance must be reacted to and compensated for if the organism is to survive. Examples of such external forces include temperature, oxygen concentration in the air, the expenditure of energy, and the presence of predators. In addition, diseases were also stressors that threatened the constancy of the milieu interieur.
What are the signs and symptoms of poorly managed stress?
Excess stress can manifest itself in a variety of emotional, behavioral, and even physical symptoms, and the symptoms of stress vary enormously among different individuals. Common somatic (physical) symptoms often reported by those experiencing excess stress include sleep disturbances, muscle tension, muscle aches, headache, gastrointestinal disturbances, and fatigue. Emotional and behavioral symptoms that can accompany excess stress include nervousness, anxiety, changes in eating habits including overeating, loss of enthusiasm or energy, and mood changes, like irritability and depression. Of course, none of these signs or symptoms means for certain that there is an elevated stress level since all of these symptoms can be caused by other medical and/or psychological conditions.
It is also known that people under stress have a greater tendency to engage in unhealthy behaviors, such as excessive use or abuse of alcohol and drugs, cigarette smoking, and making poor exercise and nutritional choices, than their less-stressed counterparts. These unhealthy behaviors can further increase the severity of symptoms related to stress, often leading to a "vicious cycle" of symptoms and unhealthy behaviors.
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:
1. The brain handles (mediates) the immediate response. This response signals the adrenal medulla to release epinephrine and norepinephrine.
2. 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.
3. 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.
4. 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).
5. 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 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 secretes epinephrine and norepinephrine. The following are the five most important concepts to remember about these two systems:
1. They are governed by a feedback loop to regulate their response. (In a feedback loop, increased amounts of a substance -- for example, a hormone -- inhibit the release of more of that substance, while decreased amounts of the substance stimulate the release of more of that substance.) 2. They interact with each other. 3. They influence other brain systems and functions. 4. Genetic (inherited) variability affects the responses of both systems. (That is, depending on their genes, different people can respond differently to similar stresses.) 5. Prolonged or overwhelming responses of these systems can be harmful to an individual.
Stress is simply a fact of nature -- forces from the inside or outside world affecting the individual. The individual responds to stress in ways that affect the individual as well as their environment. Because of the overabundance of stress in our modern lives, we usually think of stress as a negative experience, but from a biological point of view, stress can be a neutral, negative, or positive experience.
In general, stress is related to both external and internal factors. External factors include the physical environment, including your job, your relationships with others, your home, and all the situations, challenges, difficulties, and expectations you're confronted with on a daily basis. Internal factors determine your body's ability to respond to, and deal with, the external stress-inducing factors. Internal factors which influence your ability to handle stress include your nutritional status, overall health and fitness levels, emotional well-being, and the amount of sleep and rest you get.
Stress has driven evolutionary change (the development and natural selection of species over time). Thus, the species that adapted best to the causes of stress (stressors) have survived and evolved into the plant and animal kingdoms we now observe.
Man is the most adaptive creature on the planet because of the evolution of the human brain, especially the part called the neo-cortex. This adaptability is largely due to the changes and stressors that we have faced and mastered. Therefore, we, unlike other animals, can live in any climate or ecosystem, at various altitudes, and avoid the danger of predators. Moreover, most recently, we have learned to live in the air, under the sea, and even in space, where no living creatures that we know of have ever survived.
A brief history of stress
A key to the understanding of the negative aspects of stress is the concept of milieu interieur (the internal environment of the body), which was first advanced by the French physiologist Claude Bernard. In this concept, he described the principles of dynamic equilibrium. In dynamic equilibrium, constancy, a steady state (situation) in the internal bodily environment, is essential to survival. Therefore, external changes in the environment or external forces that change the internal balance must be reacted to and compensated for if the organism is to survive. Examples of such external forces include temperature, oxygen concentration in the air, the expenditure of energy, and the presence of predators. In addition, diseases were also stressors that threatened the constancy of the milieu interieur.
What are the signs and symptoms of poorly managed stress?
Excess stress can manifest itself in a variety of emotional, behavioral, and even physical symptoms, and the symptoms of stress vary enormously among different individuals. Common somatic (physical) symptoms often reported by those experiencing excess stress include sleep disturbances, muscle tension, muscle aches, headache, gastrointestinal disturbances, and fatigue. Emotional and behavioral symptoms that can accompany excess stress include nervousness, anxiety, changes in eating habits including overeating, loss of enthusiasm or energy, and mood changes, like irritability and depression. Of course, none of these signs or symptoms means for certain that there is an elevated stress level since all of these symptoms can be caused by other medical and/or psychological conditions.
It is also known that people under stress have a greater tendency to engage in unhealthy behaviors, such as excessive use or abuse of alcohol and drugs, cigarette smoking, and making poor exercise and nutritional choices, than their less-stressed counterparts. These unhealthy behaviors can further increase the severity of symptoms related to stress, often leading to a "vicious cycle" of symptoms and unhealthy behaviors.
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:
1. The brain handles (mediates) the immediate response. This response signals the adrenal medulla to release epinephrine and norepinephrine.
2. 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.
3. 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.
4. 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).
5. 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 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 secretes epinephrine and norepinephrine. The following are the five most important concepts to remember about these two systems:
1. They are governed by a feedback loop to regulate their response. (In a feedback loop, increased amounts of a substance -- for example, a hormone -- inhibit the release of more of that substance, while decreased amounts of the substance stimulate the release of more of that substance.) 2. They interact with each other. 3. They influence other brain systems and functions. 4. Genetic (inherited) variability affects the responses of both systems. (That is, depending on their genes, different people can respond differently to similar stresses.) 5. Prolonged or overwhelming responses of these systems can be harmful to an individual.
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