PSYCH 3313 Lecture Notes - Lecture 14: Lamellar Corpuscle, Secondary Somatosensory Cortex, Ventral Posterior Nucleus
5 Oct 2016
School
Department
Course
Professor
Document Summary
The sensation of touch: light touch; deep pressure; vibration; stretch; hotness; coldness; chemical pain; mechanical injury pain, the organ of touch: skin. Meissner"s corpuscles: found near surface of skin, senses pressure. Pacinian corpuscles: found deep in skin, in the joints, and in the digestive tract, senses pressure and vibration. Merkel"s disks: found near surface of skin, senses pressure. Ruffini"s endings: found deep in skin, senses stretch. Free nerve endings: found throughout skin, unmyelinated nerve endings of sensory neurons (pain and temperature: mechanoreceptors of the skin. Each has unmyelinated axon branches with mechanosensitive na+ ion channels. Ruffini"s endings: varying recceptive fields of sensory receptors. Small receptive field, better identification of small stimuli: Larger receptive field: pacinian corpuscles and ruffini"s endings: relative sensitivity. F. 3. size of receptive fields: adaptation rate of mechanoreceptors. Adaptation: refers to length of time receptor will continue to respond to unchanging stimulus: touch and thermoreceptors. Use same c fibers as pain: afferent projections to the cns.
