Unformatted text preview: train of a.p. = vibrations Somatosensory Receptors - Receptive field of Meissner corpuscles get bigger closer to body axis: from mm to cm, but never as big as Pacinian (many cms) - Very few Pacinian corpuscles: don't need very many Merkel cell sweat pores - Slowly adapting: maintained w/ pressure - Located in fingers: bottom of fingerprint ridge Merkel Cell - Cluster around sweat gland ducts Meissner corpuscle - Merkel cell or `disk' fxns as sensory receptor slowly adapting; in fingers, - Makes synaptic contactcluster afferent gland ducts w/ around sweat axon Merkel cell or `disk' functions as - Threshold response to skin indentations: makesm a sensory receptor; 20 synaptic contact with afferent Merkel afferent - Artificial stimulation of axon = sensation of axon leaf pressing against r.f. threshold response to skin indentations of 20 microns - Greater spatial acuity in smaller fingers: higher Receptive Fields: stimulation of axon gives female male density of Merkel cells and smaller r.f. of afferent sensation of leaf pressing against r.f. - Women generally have smaller fingertips than men but have same # Merkel cells = greater spatial acuity g p y they perceive finer surface detail = higher densityin smaller in touch acuity fingers; greater of Merkel Mechanoreceptor B: Proprioceptors (in deep tissue) - Muscle spindle: adequate stimulus is passive stretch of muscle (group Ia afferents) - Golgi tendon organ: adequate stimulus is active muscle contraction (group Ib) - Joint receptors: detect orthogonal (normal to surface; paciniform) or ta...
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- Fall '11
- sensory receptor, Mechanoreceptor, somatosensory receptors, Prof. MacKay