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.
The sympathetic nervous system, also part of the autonomic nervous system, originates in the spinal cord; specifically in the thoracic and lumbar regions. It controls the body's fight or flight responses, or how the body reacts to perceived danger.he sympathetic nervous system, also part of the autonomic nervous system, originates in the spinal cord; specifically in the thoracic and lumbar regions. It controls the body's fight or flight responses, or how the body reacts to perceived danger.