Ch45 Sensory Systems - Sensory Systems Chapter 45 Sensory...

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Sensory Systems Chapter 45 Sensory information is conveyed to the CNS and perceived in a four- step process. Categories of Sensory Receptors Three classes of environmental stimuli: 1. Mechanical forces - stimulate mechanoreceptors 2. Chemicals - stimulate chemoreceptors 3. Electromagnetic and thermal energy - stimulate photoreceptors (among others) Sensory Transduction Sensory cells respond to stimuli because they possess stimulus-gated ion channels in their membranes. Sensory stimulus produces a change in the membrane potential. receptor potential greater the sensory stimulus, the greater the depolarization of the receptor potential and higher frequency of action potentials Mechanical Forces 1. Touch: Cutaneous receptors respond to stimuli at the border between the external and internal environments. 2. Temperature: Thermoreceptors are naked dendritic endings of sensory neurons that are sensitive to temperature changes
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Cold receptors = near surface Warm receptors 3. Body Movements: Proprioceptors
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This note was uploaded on 05/10/2009 for the course BIOLOGY 21909 taught by Professor Jefffeaster during the Spring '09 term at Fullerton College.

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Ch45 Sensory Systems - Sensory Systems Chapter 45 Sensory...

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