Perception of pain is a complex mechanism, which involves both the central and peripheral nervous system (brain and spinal cord). There are special receptors that are sensitive to harmful stimulus called ‘noci-ceptors’. These noci-ceptors are naked nerve endings found in almost every tissue of the body and they can be stimulated by thermal, mechanical, chemical and electrical energy.

The signals are then carried via peripheral nerves to the spinal cord where pain impulses can be modified. In the spinal cord chemical substances called neurotransmitters are released. Strong pain signals are transmitted to the brain but the weak impulses are blocked by the modification in the spinal cord. This explains why rubbing a sore area decreases the intensity of pain.

From the spinal cord, the signals are transmitted to the brain which is responsible for the emotional component of pain. The brain then analyzes the signals and sends signals via motor nerves to the painful area to contract the muscles in order to withdraw the part of the body away from the harmful object. Pain has a unique property of producing an unpleasant effect, unlike other senses.