Pathophysiology

Activity of the Pain Sensors

Acute pain results from any condition that stimulates the body’s “pain sensors” (nociceptors), such as injuries, bleeds (haemorrhages), tumours, infections, and metabolic and endocrine problems. Acute pain usually occurs after surgery, physical injury or sports injuries.

Acute pain is caused by a pain stimulus that excites the pain receptors (nociceptors), which transmit stimuli to the spinal cord. The pain stimulus can then be diverted to the motor neurons, evoking a reflex response such as withdrawing a limb. Then the pain stimulus is transmitted to supra-spinal structures involved in pain processing and eventually reaches the brain, where it is perceived as pain. Supra-spinal reflexes also activate the heart and respiratory rate and induce the release of stress hormones.