Prior to the study of endorphins, opiates receptors, the physiology of pain needed to be discussed.
What is pain? This question led to pain as a sensation, caused by activation of sensory neurons. These neurons possess a high firing threshold, requiring a stimulus sufficient enough to generate pain, rather than just touch or pressure. A discussion of the three common classifications of pain followed; acute pain, chronic non-malignant, and chronic malignant. The parameters of each type were listed and then the differences between acute and chronic were discussed. The feeling of helplessness compared to the feeling of hopelessness was discussed as a psychological and physical manifestation of the level of pain threshold.