Wednesday, November 18, 2015

Stress and Your Body: An introduction

Great Courses: Stress and Your Body, by Professor Robert Saplosky,
narrated by Robert Saplosky
Robert Saplosky is a professor of biological sciences, neurology, and neurosurgery at Stanford University. His lab focuses on how stress affects the nervous system. He also has extensive field work, studying a particular population of wild baboons in East Africa - where he examines how social rank, personality, and sociality affect vulnerability to stress-related disease. He is a fantastic lecturer, and if you get the chance to watch a YouTube video of him lecturing, go for it. 

Saplosky and The Teaching Company developed the course Stress and Your Body to teach us about the detrimental effects of stress on our health. The primary textbook is his own Why Don't Zebras Get Ulcers? Which, as far as I can tell from chapter 1 versus lecture 1, is pretty much verbatim with his lectures.  

Remember that time you were lying in bed, worrying about the big exam, presentation, or event that might make-or-break you the next day? You couldn't sleep because you were ruminating about the fact that if you couldn't sleep, you'd do terribly the next day. Then you noticed some minor symptom that's been troubling you lately. Your head's been aching. Oh no! You have a brain tumor! Now not only can you not sleep because of your event the next day, but you're worried about your health.

This is the type of stress that often happens to humans. We worry about things that might happen in the future, rather than worrying about things that are happening now. Thus, our stress is generally long-lasting rather than immediate and acute. 

Animals biologically respond to stressors in very similar ways to ourselves, but their reasons for being stressed vary significantly from ours. A zebra might be munching contentedly on grass until suddenly he spots a lion. His fight-or-flight response ramps up. A part of his autonomic nervous system (responsible for controlling unconscious bodily functions) called the sympathetic nervous system is activated. His body goes into energy saving mode: it turns off all the functions that are unnecessary for fight-or-flight, and turns on the ones that are. 

He saves energy. That means his stomach stops digesting, he stops producing semen, his immune system - which requires a huge amount of energy - slows way down. Tissue repair - also another drain on energy - halts.  The rate of his heart and glucose metabolism increases so that oxygen and energy flows to the limbs for fight or flight. 

He runs.

This is a very helpful response to an immediate stressor like a lion. As soon as the zebra escapes the lion, the stress is gone and the zebra contentedly starts munching on the grass again. His parasympathetic nervous system activates, reversing all the bodily changes outlined above. He's now in rest-and-digest mode. 

When humans experience long-term stress, many of the same pathways as short-term stress are activated, leading to chronically increased blood pressure, poor digestion, dysfunctional glucose metabolism, and heightened susceptibility to infection (among many other things). Such effects on the body will be discussed in detail as we explore Saplosky's course. 


Saplosky, Robert. (2004) Chapter 1: Why Don't Zebras Get Ulcers? Why Don't Zebras Get Ulcers? Third edition. (Nook ebook pp. 13-30). Holt, Henry & Company, Inc.

Saplosky, Robert. (2010) Lecture 1: Why Don't Zebras get Ulcers? Why Do We? Stress and Your Body. The Teaching Company, The Great Courses.

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