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16 Somatosensory Receptors

16 somatosensory receptors

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Unformatted text preview: PSL302Y: Lecture 15, by Prof. MacKay# Wed., Oct.20, 2010 Somatosensory Receptors - Receptors responsible for detecting sensations in the body - Include mechanoreceptors, thermoreceptors, and nociceptors Type 1: mechanoreceptor A) Cutaneous receptors: detect skin pressure & stress B) Proprioceptors: detect forces in muscles and joints Mechanoreceptor A: Cutaneous receptors - Sensory axons classified by conduction velocity (size of sensory axon) Pacinian - Group A: all myelinated Corpuscle - A-: Large diameter, myelinated (fast conductive velocity = 50m/s) - Only mechanoreceptive - A: Small diameter, myelinated (slower conductive velocity=10m/s) - Mechano-, thermo- and nociceptors Somatosensory Receptors - C: Small diameter, unmyelinated (very slow=1 m/s) - Mixed receptors Diagram of major afferents & receptors: - Corpuscles shape character of mechanical stimulus affecting assoc sensory terminals - Pacini & Meissner corpuscles are rapidly adapting - Merkel disk & Ruffini corpuscle are slowly adapting Pacinian corpuscle Pacinian Corpuscle October 20, 2010 largest cutaneous receptor Pacinian corpuscle huge receptive field - Largest cutaneous receptor layers; hands located deep in dermal hands, - Not common: found in smooth skin of palm, fingers, lips, soles of fee;: deep in dermal feet layers of hands & feet rapidly-adapting; responds best to skin - Large receptive field200-250 Hz vibration at Pacinian corpuscle - Rapidly-adapting: resp...
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