American Huilin Institute
According to Ionocovalency, everything exists in Ionocovalency IC, the ionic energy Z* harmonized with the covalent environment r. It derived from the microscopic deduction of experiments and mathematics and correlated to the macroscopic induction of the universal observations [1-3]:
IC = I ( Z*)C(r-1).
Therefore, The biochemical reactions of the immune system in our body is always in a automatic and self-controlling mechanism that prepares the body to be in an harmonious ionocovalency (IC) state to our survival, i.e. the body needs ionic energy Z* to be controlled by covalency r-1 in normal but not excessive.
Stress is an environment factor ( r) to cause our body in excessive sufferance. When we experience some stress ( r) a bodily ionocovalent harmony (IC) is changed and the body's immune system occurred the well known "fight or flight" response  in which our body release two hormones (r) to “fight” the stress, one is cortisol and the other adrenaline. These patterns of nerve cell firing and chemical releases cause our immune system to mobilize with increased activation to restore our ionocovalency (IC). However, excessive hormones (r) would put us at increased risk of numerous health problems, and if that happens, the body's immune system according to ionocovalency (IC), to decreases excessive hormone levels (r) to “flight” and enables our body to return to normal (IC) once a perceived threat has passed.
 Zhang, Y. Ionocovalency, J. Am. huilin. Ins. 2011, 5, 1-11
 Zhang, Y. Ionocovalency and Applications 1. Ionocovalency Model and Orbital Hybrid Scales. Int. J. Mol. Sci. 2010, 11, 4381-4406
 H.S.Bracha; Ralston, TC; Matsukawa, JM; Williams, AE; Bracha, AS (2004). "Does "Fight or Flight" Need Updating?". Psychosomatics 45 (5): 448–9. doi:10.1176/appi.psy.45.5.448. PMID
15345792.http://psy.psychiatryonline.org/cgi/content/full/45/5/448. Retrieved 2010-10-04. "Walter Cannon's original formulation of the term for the human response to threat, 'fight or flight,'
was coined exactly 75 years ago, in1929.".