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STM8282 - SECTION 4: THE PHYSIOLOGY OF STRESS

 


What is the purpose of the stress response? It is designed to gear our body up to handle a challenge, protect us from danger, or allow us to take advantage of an opportunity.

After the challenge has been met, the danger has been overcome, or the opportunity grasped, the body is then supposed to return to a state in which the body can re-gather its resources to prepare for the next event. There is a complex set of chemical responses occurring here, taking the body through a series of stages. These are shown below, with discussion to follow.

Five Stage Stress Response

Stage 1-Recognition - Challenge, threat or opportunity perceived

Stage 2-Response - Physiological activity increases

Stage 3-Resolution - Challenge met, problem solved

Stage 4-Remission - Physiological activity decreases

Stage 5-Recovery - Rest and restoration of body's resources


Stage 1: The recognition stage

The moment that the sum of all the information being sensed and processed declares the presence of a threat, opportunity or challenge, the recognition stage is reached. A switch is turned on. While determining that there is a threat, opportunity, or challenge, the processing systems are also assessing how important or serious it is. This sets up the level of response that is going to be set in motion. This is a complex process, occurring at many levels of the brain, with communication and coordination between the different processing systems.

Stage 2 - The response stage

Whether the assessment is an accurate reflection of the threat, opportunity or challenge, or an inaccurate understanding of circumstance based upon misperceptions, the body will respond based upon what is perceived. The body will move to stage two.

What happens next is a complicated set of chemical processes. We will go into the chemistry of these in more detail when we look at the stress response over time. This gearing up process is primarily designed to channel the body's available resources in the most productive way towards supporting the overall well being of the person. If the person is in danger, this means giving the person focus - and energy - towards getting out of danger.

In such a case, the energy might go towards pumping more blood and more blood sugar to prepare the body to run or fight. Certain areas of the brain that might think too much - thus delaying reflexive action - might be tuned down and turned off.

If the challenge is to grasp a once in a lifetime opportunity - to win an Olympic medal, or a mate - the body might gear up in substantially different ways. The channeling of the resources will be based upon the best estimate by the information processing systems of what is most clearly needed.

In general, this gearing up will include what are called ergotropic responses. (Kiely, 1974) This is to say, the responses that will dominate will be those that tend to cause the body to move towards a state of increased arousal. This will prepare the body for work, but will also use more energy.

The ergotropic responses tend to work first through the sympathetic nervous system. This is a system of nerves, glands, chemicals and hormones that are involved in regulating important physical activities such as breathing, the regulation of the heart, appetites, sleep, and many other things.

The sympathetic nervous system, when it responds, causes the chemical changes that gear the body up. Some of the effects of sympathetic discharge are increased heart rate, higher blood pressure, faster breathing, increased perspiration - in short, all the things we associate with stress.

The body also sends more blood sugar out of the liver into the blood stream and sends more chemicals into the brain in areas that will help the person focus on tasks, or not focus on pain, whichever is most needed. As the level of ergotropic responsiveness increases, a person’s ability to get and stay focused improves, but only if the level doesn’t get too high. If the activation goes past a certain point, the body won’t increase focus and attention, but will instead move to a state of increasing disorganization and loss of focus. The relationship between sympathetic activation and, first, increases then decreases in focal attention was first noted early in the 20th century. This phenomenon is known as the Yerkes-Dodson Effect. (Yerkes and Dodson, 1908)

The body will continue with this approach, gearing up as much as the body thinks is needed, until the event that caused the response is resolved or overcome. The entire time that these processes are occurring, the information processing systems continue to evaluate the situation.

If the threat, opportunity or challenge continues to increase, increasingly involved levels of response are set in motion. If there is a decrease in the threat, opportunity or challenge, the body slows down the amount of chemicals that are being released.

At some point, hopefully, the efforts generated by the response will have the desired effect, and the threat, opportunity or challenge will be handled. This will be noted by the information processing systems.

There is one very important exception to the activation of the ergotropic nervous system. If the body’s appraisal systems perceive the challenge to be completely overwhelming to the person’s available resources – to the point where it would be a complete waste of energy to engage the sympathetic nervous system – then the appraisal process leads to the engagement of physiological resources that cause the body to move to a state of diminishing use of physiological resources.

The emotions that are likely to accompany this type of down-regulation process are depression, despair, apathy, and emotional paralysis. This system’s adaptive purpose is to conserve valuable resources for a time in which the context changes enough to allow for the use of resources to be more effective.

Stage 3 - The resolution stage

When it is perceived that the threat is over, there is a dramatic change in the body's chemistry. This heralds the start of stage 3, the resolution stage. The ergotropic responses get turned down or turned off, and another set of responses begins to dominate the body's chemistry.

This second, complimentary set of responses is called the trophotropic responses. (Kiely, 1974) These responses have the function of slowing down and relaxing all the parts of the body that had been charged up during the ergotropic response phase.

The trophotropic responses are largely controlled through the parasympathetic nervous system. Like the sympathetic nervous system, this is a complicated system of nerves, glands, chemicals and hormones. In fact, the parasympathetic nervous system has connections - and effects - on many of the same parts of the body as the sympathetic nervous system.

The trophotropic response system, however, has different nerve pathways, and works with somewhat different chemicals, in these same areas of the brain and body. As you might have suspected, the trophotropic system has the effect of turning down the physiological state of the person. The trophotropic systems cause the person's heart rate and blood pressure to go down, the muscles and breathing to relax, and other changes that work to bring the body back down from its aroused state.

The movement through a simple stress response curve is marked by a rapid increase in ergotropic response, where the sympathetic nervous system is dominant in the first phases, followed by a slower trophotropic response phases, where the parasympathetic nervous system is dominant, helping the person to return to a state of rest and relaxation where the body’s energy resources can be replenished.

In fact, this is not exactly what happens. In a more usual stress response, both ergotropic and trophotropic responses are usually operating at the same time, and often in complex ways. Left on their own, the ergotropic responses may move the person to a state of over-arousal, where fright or panic set in if the challenge or threat is high enough.

The trophotropic responses, when well-developed and working well, operate in a delicate kind of opposition to the ergotropic responses, trying to settle things down, and help create a state of focused calm and relaxation, so the energy can be used wisely. They may be working hard to control the ergotropic responses, keep them from getting too overly charged up.

Athletes that can perform at a very high level achieve an exquisite balance between the ergotropic and trophotropic systems. They can be working at a very high level of arousal while staying extremely calm.

It is much harder to control the trophotropic response system to make this happen. For reasons having to do with our evolutionary heritage, the ergotropic system has built-in advantages when it comes to being the dominant force in our responses to challenges. Learning to get a little too anxious in the face of dangers and challenges comes relatively easily to most people, while learning to stay very calm in the face of danger requires a substantial amount of effort to build and strengthen the necessary skill sets.

As we will see later in this training, however, it can be done. The skill involved is a powerful tool to utilize in terms of stress management.

It is possible for both the ergotropic and the trophotropic response systems to be over-active at the same time in response to a sudden dramatic event. When extreme ergotropic response and extreme trophotropic response occur at the same time in responding to a single event, this dual over-reaction is what produces fainting.

Stage 4 - The remission stage

When the ergotropic responses are stopped, and the trophotropic responses increase to the point where they begin to be dominant, this chemical shift signals an entry into stage 4 of the stress response cycle, the remission stage. This is when the body tries to get everything settled down and back to a less aroused state.

The remission stage is required because the trophotropic systems don't take over immediately and completely get the ergotropic systems to calm down. There is usually a lag time for everything to return to normal.

If you have ever had an exciting experience, or a frightening one, you have probably experienced the lag time that occurs in the remission stage. A close call in an automobile accident, or your favorite team winning an exciting game, can leave you in a state of arousal for several hours.

The chemicals that produce arousal are re-absorbed by your body fairly slowly. Your body has important, safety related reasons for gearing up more quickly than you can calm down. But it can create wear and tear if you spend a lot of time geared up.

Stage 5 - The recovery stage

Once the body has calmed down, you reach the final stage of the stress response. This is the recovery stage. This is the stage in which the body rests and restores itself, and repairs any damage done.

If the event which precipitated the response was very stressful, the body will have used up considerable resources. The person will be tired and will need time to prepare for the next event. If physical damage was done to the body, additional energy will be used for repair work. This recovery is essential for maintaining overall well being.

Without sufficient rest, recovery and repair time, the body enters a period of ongoing breakdown. The body's chemistry is simply not designed for being continuously pushed to the edge of its limits without this time for restoration.

This five stage response curve is the body's best approach to handling the challenges of the world, and it is an almost perfect design for the time in which it was designed. Unfortunately, that time was thousands of years ago. This has tremendous implications for stress management in modern life.

Here is how the stress curve would have worked thousands of years ago. A small human walks across a grassy plain. He/she sees a large predator, and instantly recognizes the threat to his/her safety. In seconds, his/her body is operating in high gear, positioning the body for a run for the nearest point of safety, perhaps a tree with a low hanging limb. If luck is with him/her, he/she makes it up the tree to safety ahead of the pursuit of the predator. The predator stalks around the tree a few times, then leaves to find other prey. The danger is past.

After a few minutes, the person comes down from the tree and hurries back to the safety of his/her group or village, where he/she can relax and return to a state of calm. Around the fire that night, he/she tells the others all about his/her close call. With limbs tired and aching from the race to safety, he/she falls asleep, where muscles can heal and energy can be restored. The next day he/she awakens refreshed and ready for another day of challenges.

Can you recognize the five stages in this story from our past? Each of the stages has its own discrete part to play in protecting the person in his/her environment. At that point in our history, stress was often managed exactly like this. In the course of the day, there would be discrete events that generated a stress response. The event would quickly be resolved, and the person would just as quickly move to the remission and recovery stages. Unfortunately, this is not the way that modern life works.

In modern life, there are not discrete events - each separated by time - that cause stress, with each event moving to completion through each of the five stages of response. The stresses are often events that can't be resolved quickly and easily. There can be multiple events happening at the same time, so that the person can't focus on bringing any single one to a point of resolution. Or, a person may be just ready to bring one stress to a point of resolution when two or three more pop up, causing the body to stay geared up.

This is important, because the chemistry and design of the body work best when the stress response brings the body through all of the five stages, and allows the person enough time in the recovery stage to repair and restore things before the next stress.

Without enough time in the recovery stage, the body can't repair and restore itself well enough to get ready for the next challenge. That's when things get complicated, and the body can begin to break down. The systems of response are designed to work best when the response is quick, and the return to a state of recovery just as quick.

The body does have back-up systems for times when the stress is not able to be managed in a short time, but there is a price to be paid for managing the stress over a longer period of time. This is the next part of our training - to look at the mechanisms used by the body when stress goes on for too long. We will see how it begins to affect the body over time. First, though, let's look at stress exercise number three.

Stress exercise #3:

Look at your list of stressful events from the first two exercises. Examine how many of those events moved all the way through the five stages of the stress response, and how many got stuck before you could get them to the resolution and response phases. Examine what this meant in terms of how stressful the event felt.


Review Questions for Section IV

At this point in the training, the trainee should be able to answer the following questions:

What are the five stages of the stress response curve?

Which system is slower to create changes in your body – the ergotropic or the trophotropic? Why is this so?

What is happening to the ergotropic system and the trophotropic system when someone faints?

Which stage is the most important in terms of managing stress long-term?

 

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