Nociception can be described as a response to harmful or potentially harmful stimuli (chemical, mechanical, thermal). It includes four stages:
1.Transduction or first phase: A noxious stimulus occurs (injury, burn, incision) and it is transformed into a electrical signal that can be carried via transmission.
2. Transmission or the 2nd phase: the pain signal travels to the central nervous system, first to the spinal cord than to the brain.
3. Perception or the 3rd phase: occurs in the cerebral cortex where the perception of pain is generated (the conscious awareness of a painful sensation).
4. Modulation-last phase: pain message is usually inhibited through this phase.
