August 6, 2009
Why Zebras Don’t Get Ulcers by Robert M. Sapolsky, gives a description of the inner workings of the human, and animal, stress response. He talks about what physiologically happens to people when they remain in a state of stress of a long period of time. The immune response, depression, aging and death, and sexual reproduction are just some of the topics Sapolsky discusses and how stress affects each of these.
Why Zebras Don’t Get Ulcers
I chose Why Zebras Don’t Get Ulcers (1994) because I was intrigued by the similarities between humans and animals in regards to their responses to acute and chronic stress. As a medical professional, I feel that I have a strong background in human physiology and therefore could relate to this book. It did not disappoint. This book is written by Robert M. Sapolsky, a professor of biological sciences, as well as neurology and neurological sciences at Stanford University. As a neuroendocrinologist, he has done extensive research in the area of hormonal response to stress and their effects on the body. As a research associate for the National Museums of Kenya, he spends time studying baboons in their natural habitat and the stressors that they endure along with stress related illnesses that their environment may bring about. In Why Zebras Don’t Get Ulcers, Sapolsky examines the adverse effects of long-term stress and the associated physical and mental damage it can cause. During the first five chapters, Sapolsky goes into great detail, engrained with humor, about the physiological changes that happen in our bodies during periods of stress. He explains the principles of the “fight or flight” response brought on by the body’s sympathetic nervous system, which is responsible for preparing our bodies for exertion through the release of glucocorticoids. These hormones raise our heart rate in order to increase the flow of oxygenated blood to the working muscles; gut motility decreases as blood is shunted to the vital organs; pupils dilate to increase light perception; and our airway passages dilate allowing us to increase respiration in order to bring in more oxygen which is much needed for the exertion our body is under. All of these changes occur in just fractions of a second; however it takes longer for these effects to leave the body once the threat or stressor is removed. Sapolsky goes on to explain to the reader why other changes or responses happen during activation of the sympathetic nervous system. He humorously details why we sometimes experience loss of urinary bladder or bowel control during a stressful encounter. If we were to get up off of our couch, walk outside the front door and come face to face with a hungry lion, then our sympathetic nervous systems will take over, secrete the stress hormones, and put our bodies through the changes I described above. In addition to preparing our bodies for fight, it will also temporarily stop the digestive process, in order to expend the body’s energy where it is needed the most. By stopping this process, the small intestines stop their contractions; however the large intestines continue their peristalsis movement in order to rid the body of excess “baggage”, or fecal matter. It’s much easier to move quickly for humans and animals alike, whether running from a shooting down the street, or running from a hungry lion across the grasslands, when you’re not carrying a couple of extra pounds of feces. The portions of this book that were of great interest to me were when the author talks about repeated stimulations of the sympathetic nervous system and its potential harmful effects on the body over time. These stimulations don’t always have to be at the level of being face to face with the hungry lion. In our everyday modern lives, we have stressors thrust upon us, and even sometimes without our knowledge. Our reactions to the smaller stressors...