Pain

It is an unpleasant sensory and emotional experience, which we primarily associate with tissue damage.

It is whatever the person says it is.

Physiologic processes involved in pain perception (nociception) include:

Physiologic processes:

Injured tissue releases chemicals that affect nociceptors sending pain message up sensory neuron

Physiologic processes:

Begins when a mechanical, thermal, or chemical stimulus results in tissue injury or damage stimulating the nociceptors, which are the primary afferent nerves for receiving painful stimuli.

Physiologic processes:

Noxious stimuli initiate a painful stimulus that results in an inflammatory process leading to release of cytokines and neuropeptides from circulating leukocytes, platelets, vascular endothelial cells, immune cells, and cells from within the peripheral nervous system.

Physiologic processes:

Pain impulse from the nociceptors (Aδ or C fibers) relays the pain from the spinal cord to the brain

Physiologic processes:

Results in the conduction of an impulse in the primary afferent neurons to the dorsal horn of the spinal cord.

Physiologic processes:

Neurotransmitters are then released and concentrated in the substantia gelatinosa and bond to specific receptors.

Physiologic processes:

Studies have shown that the emotional status (depression and anxiety) affects directly the level of pain perceived  and thus reported by clients.