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