The momenta of individual objects changes. The total momentum remains constant. I have to disagree. If you have two cars that collide head on, the momentum of both vehicles stops. The ENERGY created by the impact causes usually, some reverse momentum but the momentum is lost.
As the SNS continues to trigger physical reactions, it causes a wear-and-tear on the body. It's not so much what chronic stress does to the nervous system, but what continuous activation of the nervous system does to other bodily systems that become problematic.
But allows the body to react in times of emergency. 2 divisions of ANS Sympathetic nervous system acts in emergency Parasympathetic counter acts the sympathetic ns after the emergency SNS increase heart rate increase resp. rate increase b/p decrease digestive system activity PNS decrease heart rate decrease resp. rate decrease b/p increase digestive ...