Believing that stress is a synonym of irritation and overstrain, we make a deeply mistake. Traumatic stress situation is caused by more than 1400 physiochemical body reactions! And not all of them have as result a bad mood, which, by the way, can be avoided.
Adrenaline, endorphine and enkephaline - these substances are developed at the time of difficulties and create all the attendant feelings.
Stress is an ancient technique of survival. Therefore, its mechanism is primitive: operational, but inaccurate. Any special situation, a number of retiring won, instinctively scares us and adjusts the body to "fight". It doesn't matter: either somebody stepped on our leg in the subway, or we got fired - the "emergency" hormones are produces: adrenaline and norepinephrine. They are forced to work intensively in the body and increase by many times the muscle strength and mental activity.
The second phase of the stress mechanism includes the endorphines' and enkephalines' production - the so called "mood" hormones. Enkephaline causes negative emotions (if developments threaten the survival or are contrary to its tasks). It also reduces the pain. The endorphine causes positive emotions when things are conducive to the well-being of the body. It is a matter of relaxation and euphoria. That is to say, judging by how people cope with the difficulties, this make them happy or upset.
The Chinese word "stress" is a two hieroglyph, which means danger and opportunity. Everyone chooses for himself what would stress mean for him/her.