Week 3-- Lecture Notes on Stress
Slide 1—Title Slide.
Slide 2—Definitions of stress and stressor are on the slide. Notice the point at the bottom: How we think about a situation or an event can affect the level of stress we feel. Let me give you an example. In a different course that I have taught for years, my students are required to do a presentation at the end of the semester. It’s only 5 minutes long. Many of them are fine with the assignment; they get up and present to the class and are seemingly at ease. But there are always a few in the class who really struggle with this and become very nervous. Their hands may shake as they try to read their notes; they rush through the words as quickly as possible so they can return to their seats; they don’t make any eye contact with their peers. I’ve even had a few who don’t show up at all, prefe
ing to get a “0” on the assignment rather than do the presentation. Every student is asked to do the same thing, all are engaging in the same situation, yet the level of stress from one student to the next is very different.
This difference is inside of their heads—in how they are thinking about the situation. For those who are very stressed out—they are thinking that they are going to fail in some way or emba
ass themselves in front of others. They wo
y that they will get up in front of their peers (and me) and forget what they intended to say, or they will make a mistake. Or they wo
y that others will make fun of how they look or how they speak. These same thoughts are not likely to be occu
ing in the heads of the students who are at ease with the assignment. Bottom line here: a lot of our stress is generated by our thoughts, by how we are thinking about a situation or event.
Slide 3—Stress is a great example of a mind
ody interaction. When we think something is stressful, it registers in an area of the
ain called the hypothalamus (see image on slide). The hypothalamus then activates the Autonomic Nervous System (ANS) which controls all of those functions we don’t have conscious control over:
eathing, heart rate, temperature, digestion, etc.
The ANS is divided into 2
anches: the sympathetic and the parasympathetic. What do they do?
Sympathetic—regulates arousal; it speeds up all of the ANS functions.
Parasympathetic—regulates relaxation; it slows down all of the ANS functions.
The sympathetic nervous system is the one that is activated when we are feeling stressed out.
Slide 4—You might have heard of the fight or flight response (also called the stress response). It is a series of bio-chemical changes in the body that provide a burst of energy to deal with a perceived threat. Fight or flight gets the body ready to take physical action in response to the stressor. Notice the words fight and flight both imply action/movement.
This is a survival mechanism from earlier days in our evolutionary history. The hypothalamus that you saw in the previous slide is in a very primitive, older area of the
ain that all mammals have in common. Thousands of years ago, this fight or flight mechanism saved our lives because the main stressors we faced were wild animals. When our fight or flight alarm was activated, it gave us the energy we needed to either run away from a threatening animal or to stay and fight. Being able to fight or flee could mean the difference between life or death when facing a bear or a tiger. (Note—you sometimes hear this described as Fight, Flight, or Freeze. Freezing means remaining perfectly still, a bit like “playing dead,” which in earlier times could be an effective strategy against some predators.)
Our stressors today are quite different. Most have nothing to do with actual life or death situations, but our bodies still react the same way. The fight or flight mechanism is activated even though our stress may be about the everyday hassles of balancing work, school, and family rather than facing down wild animals. In these situations, fighting or fleeing are no longer helpful responses. But that evolutionary wiring in our
ains still exists. It is a mechanism that is outdated, but we are stuck with it.
Slide 5—These are the changes that occur in the body in response to the fight or flight response.
Notice that the heart rate accelerates (speeds up), which means the heart has to work harder and faster to keep the blood moving all throughout the body. Your blood pressure also increases, although that isn’t shown specifically on the diagram.
You can also see that we are
eathing faster to
ing in more oxygen which would be essential if we are going to take action.
Our muscles tense as they get ready to move.
The liver converts stored glycogen to glucose because the body needs more fuel if it is going to run or fight. This could be a problem for diabetics who often find it becomes harder to manage their glucose levels when they are going through stressful periods.
The bladder relaxes which means you might find yourself heading for the bathroom to urinate more often when you are stressed.
You probably have heard of adrenaline (also called epinephrine) which is one of the main stress hormones; it is produced and released from the adrenal glands that sit on top of the kidneys. A second hormone called cortisol is also released from a different part of the adrenal glands in fight or flight. They both help us in the immediate moment to move faster.
Your senses are affected—vision and hearing become more alert or more heightened—during fight or flight. The pupils in your eyes open wider to let in more light and you develop “tunnel vision,” which allows you to focus more directly on what is most important.
Finally, notice on the slide that the one change that represents a “slowing down” rather than a “speeding up” is digestion. Blood flow is redirected away from the stomach to the major organs (heart, lungs) that will play a vital role in allowing you to fight or flee. Digestion is not considered important to immediate survival because any food in your stomach will take a couple of hours to be digested and abso
ed. That’s why sometimes when you are under stress, it might feel that whatever is in your stomach is just sitting there like a
ick.
I think we can all agree that those are a lot of changes that take place as a result of perceiving or thinking that something is threatening. As I said earlier, fight or flight is a good example of a mind
ody interaction. It may start as a stressful thought in the
ain, but quickly it turns into a full-body response involving virtually all of our organ systems.
Slide 6—Whether or not stress harms your health depends on how long it lasts. Stress can be defined as acute or chronic.
Acute means short-term, something that has a definite end point so that you know it isn’t going to last very long. Examples of acute stress would include the class presentation I mentioned earlier, going for a job interview, maybe a first date, taking an exam. If you find these situations stressful, your fight or flight response is activated and all of the changes we described on the last slide would be happening in your body. But those changes don’t last for very long. You might be very stressed out for an hour or so before and during the job interview or the class presentation. But after the event is over, your fight or flight “alarm” is shut off (the stressor has ended) and your body goes back to a state we call homeostasis (which is a stable internal environment or physiological balance). No harm is done in this situation because your body is resilient enough (able to bounce back) after relatively
ief periods of ANS arousal in fight or flight.
But what about when stress is chronic? That means it lasts for long periods of time with no definite end point in sight. Examples would be financial problems, being in a difficult or abusive relationship, the death or serious illness of a loved one, your own serious illness, academic failure, etc. None of these will end in an hour or two. Because they can persist for weeks or months, the body doesn’t get to return to homeostasis. The heart rate and respiration rate remain elevated, and so does blood pressure, for days, weeks, months. Your muscles stay tensed. Too much glucose pours into the blood. Digestion continues to be impaired. I’m sure you can see the problem here. It is the chronic stress that causes harm to the body. Too much chronic stress has a negative effect on our physical and mental health.
Slide 7—Hans Selye was a scientist who did much of the early research into stress and its effects on the body. He came up what is called The General Adaptation Syndrome to explain these effects. You can see on the slide that he divided the Syndrome into 3 different stages:
Alarm Stage—This begins as soon as you perceive something to be a threat. Homeostasis is disrupted by the activation of the sympathetic nervous system and the Fight or Flight Response. If the threat stops quickly (as in acute stress), then the next 2 stages don’t occur.
Resistance Stage—When the threat is ongoing (chronic), then the body has to make adjustments to fight against the continuing stress. Here your body realizes that the stress is not going away and so its defenses stay elevated (heart and respiration rates stay high, blood pressure stays high, muscles remain tense, etc).
Exhaustion Stage—Your body cannot maintain “resistance” for long periods of time. Eventually, these elevated levels of physiological change begin to wear you out, leaving you feeling overwhelmed and exhausted. It is in the exhaustion stage that diseases can begin to occur. Notice that you can be exhausted mentally from stress, not just physically. Mental exhaustion can leave you vulnerable to anxiety, depression and other mental health problems.
Slide 8 —On this slide you can see the range of health problems that are linked to stress. These are the problems we begin to see in Selye’s Exhaustion Stage.
Note that 80-85% of the health problems we visit our doctors for are either caused by stress or made worse by stress. Think of how many health care dollars we would save if we all began to practice some type of stress management!
Heart disease and hypertension—this is pretty obvious since the heart has to work harder