Physiological pain is termed nociceptive pain. This
is due to stimulation of the sensory nociceptors, located
in tissues, when damaged. Somatic pain, from the skin
and superficial structures, is usually well localized
and can be described as aching, sharp, throbbing or
pressure-like. Visceral pain, from deep structures, is
less well localized. It often presents as referred pain
and may be described as a deep, aching pain.16