There is a great book out there called ¨Why zebras don´t get ulcers¨ by Robert M. Sapolsky, that I highly recommend everyone to read. This book describes perfectly what stress is and how our body reacts to it. Thanks to this book and it´s well done research I have learned a little bit more about what stress is and how it can affect us. And I will try to explain this in the following blog.
First, let´s clear up some simple terms.
- Stressor- is anything in the outside world that knocks you out of homeostatic balance.
- Stress response- is how your body reacts to the stressor.
So let´s give an example to clarify things: Imagine you are walking down the street and a lion (stressor) comes out of nowhere and starts chasing you, so you decide, if clever, to run. The body has to react to mobilize energy, so it raises the heart rate, as well as blood pressure and breathing rate. Arteries are relaxed to let the diverted blood into your muscles (you are going to have to run), veins get more rigid because this causes the blood to return with more force. The body has to halt expensive building projects (you are going to need all the energy possible), so digestion is inhibited. Growth and reproduction are also affected (who cares about the future, you got to take care of the present), and immunity is also inhibited. The body has to mobilize energy so it secretes 2 hormones (it releases more than 2 but for simplicity reasons): GLUCOCORTICOIDS AND GLUCAGON. These hormones cause triglycerides (where fat is stored) to be broken down into free fatty acids and glycerol, it also causes glycogen to broken into glucose and protein into amino- acids. So, now you got all these simple forms of ¨energy¨ in your bloodstream, so that you can use them to outrun the lion.
Now, all this is good if the lion chases you one day, but imagine if the damn¨ lion¨ is chasing you everyday of your life. Your heart would have to work more, blood pressure would increase, veins become more rigid, vessels have to work harder so they build a thicker muscle layer, they also have a greater change of being damaged and inflamed since blood pressure is going up. And on top of that you got the amino acids, glucose and free fatty acids flowing through your blood, meaning that if you add all that up you got a greater probability of clogging those veins up (atherosclerosis).
Also, insulin, which promotes storage of energy and stimulates protein synthesis, goes down. Because when faced with a stress we don´t want to store energy, we want to mobilize energy. So all those who want to build muscle and are under lots of stress will have a harder time developing muscle. And let´s not forget that mobilizing all this energy is ¨expensive¨, meaning you are using energy and that could lead to ¨chronic fatigue syndrome¨.
Now all this doesn´t mean that if you have stress you are going to get sick, in fact, some people are stress all their lifes and never get sick, but it does INCREASE your risk of getting a disease that makes you sick. So what do we do about it? We will talk about that in my next blog, but before I go, I do want to say that if the ¨stressor¨ is really a lion, RUN, as fast as you can :).
Hoped you enjoyed it!
Sapolsky M R, Why Zebras Don´t Get Ulcers. Third Edition, St.Martins Griffin, New York 1994.