JAPAN 1 Lecture Notes - Lecture 3: Periaqueductal Gray, Somatotopic Arrangement, Somatic Nervous System
Document Summary
Sensory process that provides signals that trigger pain. Can be controlled from within the brain itself. Nociceptors are activated by stimuli that have the potential to cause tissue damage. > membranes of nociceptors contain ion channels that are activated by strong mechanical stimulation, extremes in temperature, oxygen deprivation, and exposure to certain chemical, and other. Simple stretching or stretching or bending of the nociceptor membrane activates mechanically gated ion channels that cause the cell to depolarize and generate action potentials. > in addition, damaged cells can release a number of substances (proteases, atp, k+ ions= that can cause ion channel opening. > transduction of painful stimuli occurs in free nerve endings of unmyelinated c fibers and lightly myelinated a fibers. >polymodal nociceptors -> majority of nociceptors; respond to mechanical, thermal, and chemical stimuli; mechanical nociceptors, thermal nociceptors, chemical nociceptors. Initially sharp pain -> first pain; transmitted by a fibers, that carry information from damaged thermal and mechanical nociceptors.
