NROC64H3 Chapter Notes - Chapter 12: Trigeminal Nerve, Proprioception, Posterior Parietal Cortex
17 Mar 2012
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Somatic sensation: enables body to feel, ache, chill and know what parts are doing. Sensitive to many kinds of stimuli: pressure of objects on skin, position of joints and muscles, distension of bladder, temperature of limbs and brain. Somatic sensory system is different from other sensory systems: receptors distributed everywhere on body touch, temperature, pain and body position, is catch-all name collective category for all sensations that aren"t the 5 senses . Begins at skin major skin types are hairy and glabrous/hairless. Outer layer epidermis- and inner layer dermis. Finger can feel raised dot of 0. 006 mm high, 0. 04 mm wide (braille dot"s 167x higher) Most sensory receptors are mechanoreceptors sensitive to physical distortion (i. e. bending and stretching) Axons have mechano-sensitive ion channels their gating depends on stretching or changes in tension. Best studies and largest receptor is pacinian corpuscle deep in dermis largest of 2mm and 1 mm in diameter 0 (200-300 hz; hand on vibrating speakers)
