PSIO 201 5th Edition Lecture 36 Outline of Current Lecture I Introduction to Sensory Function II Gustatory III Olfactory IV General Senses V Special Senses VI Reception Field VII Specificity VIII Sensory Transduction Current Lecture General Senses receptors distributed throughout body not collected within specialized sense organs 4 Types 1 2 3 4 Pain receptors Temperature thermoreceptors Touch pressure body position mechanoreceptors Chemical stimuli chemoreceptors O2 CO2 General Senses Somatic Senses vs Visceral Senses Somatic body surface surface temp touch pain and muscle soreness Visceral internal organs stomach ache gut cramps etc Special Senses receptors congregated in specialized sense organs 5 Types 1 2 3 4 5 Smell olfaction nose Taste gustation tongue Sight vision eye Balance Equilibrium ear Sound hearing ear Specificity of Sensation Regardless of stimulus modality all sensations is read in the CNS as electrical signals we can discriminate between different types of stimuli because different receptor types respond preferentially to different stimuli A mechanoreceptor is more sensitive to touch than to light a photoreceptor is more sensitive to light than to touch Receptive Field Discrimination between two similar stimuli e g two points on the body surface two sounds of similar pitch is dependent on the number of receptors within an area of sensory surface Sensory Transduction Common Steps 1 Stimulus arrives at receptor and alters membrane potential of receptors graded potential depolarizing or hyperpolarizing receptor potential 2 Receptor potential influences directly or indirectly rate of AP production in a sensory neuron the afferent pathway 3 Aps travel to CNS along afferent pathway 4 CNS interprets processes these incoming signals Sensory Transduction Interpretation of afferent sensory input The brain assumed that any signals coming in along a sensory afferent from a particular receptor reflects stimulation by the appropriate stimulus i e pressure photon All other characteristics of the stimulus e g intensity duration are conveyed by the prequency and pattern of the incoming signals General Senses 4 Types 1 2 3 4 Nociceptors pain Thermoreceptors temperature Chemoreceptors e g O2 CO2 H Mechanoreceptors touch pressure proprioception Special Senses generally show a greater degree of selectivity for specific stimuli same principles of receptor function sensory transduction apply
View Full Document
Unlocking...