11 28 07 - Sense Organs I

11 28 07 - Sense Organs I - Chapter 19: The sense organs...

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Chapter 19: The sense organs Sensory neurons may (1) respond directly to the environment or (2) receive communication from specialized cells. 1) free nerve endings 2) receptor cells Receptor cells use 2 strategies for communicating to afferent neurons 1) Phasic receptors – stimulation causes a change in electrical activity of the cell membrane that results in a signal to a neuron a. Free nerve endings (Neuron) i. Phasic receptors - when they receive an input it signals to the neuron to the CNS 1. Most sensory receptors are phasic 2) Tonic receptors (specialized cell) – receptors always signal to neuron but stimulation of receptor increases or decreases signaling a. Tonic receptor - always on i. Will produce electrical impulses at a regular interval throughout time Transducers of energy – energy transformation is received. Perception occurs in the central nervous system. Nervous system Transduces the impulses Transforming energy to something the body can understand The perception of the stimulus is something that occurs at the brain Physical signal electrical signal brain The neuron only conveys one sense but the perception of it is interpreted at brain Types of receptors Receptors respond to various modalities of energy, converting that energy to electrical signals Chemoreceptors – respond to specific chemical stimuli (olfaction, gustation) have a specific receptor for a type of chemical Mechanoreceptors – respond to touch, pressure, pain, 1. sense movement Proprioreceptors - respond to stretch in muscles, tendons, and other connective tissues present within muscles and tendons i. Senses when a muscle or tendon is contracting or when stress is placed on muscle/ligament ii. It enables us to know our position without looking iii. Not consciously aware of it Lateral line, ear, and electroreceptors – sense vibration, gravity, and electric fields i. In lateral line system and inner ear
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This note was uploaded on 08/16/2008 for the course BIOL 276 taught by Professor Johnson during the Spring '07 term at UNC.

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11 28 07 - Sense Organs I - Chapter 19: The sense organs...

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