When a person undergoes surgery, they must take anesthesia so that the pain is not felt by the person who is undergoing surgery. This is simple enough, but not so when I began to wonder how pain is felt (i.e.,the degree of which the level of pain is identified in the brain). IOW, do the chemical reactions that constitute what we refer to as "physical pain" occur? If so, to what level? Are they subconsciously registered? How does anesthesia prevent us from feeling physical pain....or does it PREVENT?