Sensory Physiology Summary

Sensory Physiology Summary - BMED 3100: Systems Physiology...

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BMED 3100: Systems Physiology Sensory Systems Summary Sensory reception: Detection of stimulus energy by sensory receptors Stimulus – input to the system (external or internal) 1. Stimulus affects ionic permeability and membrane potential of the receptor cell 2. Each receptor has an adequate stimulus – a particular form of energy to which it is most responsive 3. Law of specific nerve energies = specificity of receptor for a particular stimulus type Receptors – transducers that convert stimuli into electrical signals Type based on morphology : 1. Somatosensory receptors for somatic senses are simplest: a. Naked nerve endings b. Nerve endings encased in connective tissue capsules 2. Sense organs – specialized receptor cells (not necessarily neurons) synapsing onto sensory neurons Type based on stimulus specificity : 1. chemoreceptors – chemical ligands binding to receptor 2. mechanoreceptors – respond to various mechanical energy forms: pressure, vibration, sound 3. thermoreceptors – respond to temperature 4. photoreceptors – respond to light 5. nocireceptors – respond to noxious stimuli Type based on adaptive speed 1. slowly adapting receptors are tonic 2. fast adapting receptors are phasic Sensory transduction 1. Resulting depolarizing current produces a graded (generator or receptor) potential and initiates neurotransmitter release a. generator potential – graded potentials whose amplitude is proportional to the strength of the stimulus b. receptor potential usually refers to non-neural receptors 2. Receptor potential triggers action potential if above threshold Amplification 1. The strengthening of stimulus energy that is detected by the nervous system 2. May be part of, or not part of, transduction Transmission 1. The conduction of sensory stimuli to the CNS
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This note was uploaded on 01/12/2012 for the course BMED 3110 taught by Professor Staff during the Spring '08 term at Georgia Institute of Technology.

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Sensory Physiology Summary - BMED 3100: Systems Physiology...

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