15_LectureOutline

15_LectureOutline - Sensory Information Afferent Division...

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Sensory Information * Afferent Division of the Nervous System * Receptors * Sensory neurons * Sensory pathways * Efferent Division of the Nervous System * Nuclei * Motor tracts * Motor neurons Sensory Receptors Specialized cells that monitor specific conditions in the body or external environment * When stimulated, a receptor passes information to the CNS in the form of action potentials along the axon of a sensory neuron * Sensory Pathways * Deliver somatic and visceral sensory information to their final destinations inside the CNS using *Nerves *Nuclei *Tracts * Somatic Motor Portion of the Efferent Division * Controls peripheral effectors * Somatic Motor Commands * Travel from motor centers in the brain along somatic motor pathways of *Motor nuclei *Tracts *Nerves Somatic Nervous System (SNS) Motor neurons and pathways that control skeletal muscles Sensory Receptors * General Senses * Describe our sensitivity to *Temperature *Pain *Touch *Pressure *Vibration *Proprioception
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Sensation The arriving information from these senses Perception Conscious awareness of a sensation Special Senses Olfaction (smell) * Vision (sight) * Gustation (taste) * Equilibrium (balance) * Hearing The special senses are provided by special sensory receptors * Special sensory receptors Are located in sense organs such as the eye or ear * Are protected by surrounding tissues The Detection of Stimuli Receptor sensitivity Each receptor has a characteristic sensitivity Receptive field Area is monitored by a single receptor cell * The larger the receptive field, the more difficult it is to localize a stimulus The Interpretation of Sensory Information Arriving stimulus Takes many forms: * physical force (such as pressure) * dissolved chemical * sound * light Sensations Taste, hearing, equilibrium, and vision provided by specialized receptor cells * Communicate with sensory neurons across chemical synapses Adaptation Reduction in sensitivity of a constant stimulus * Your nervous system quickly adapts to stimuli that are painless and constant * Tonic receptors Are always active * Show little peripheral adaptation * Are slow-adapting receptors
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Remind you of an injury long after the initial damage has occurred Phasic receptors Are normally inactive * Become active for a short time whenever a change occurs * Provide information about the intensity and rate of change of a stimulus * Are fast-adapting receptors * Stimulation of a receptor produces action potentials along the axon of a sensory neuron * The frequency and pattern of action potentials contain information about the strength, duration, and variation of the stimulus * Your perception of the nature of that stimulus depends on the path it takes inside the CNS Classifying Sensory Receptors * Exteroceptors provide information about the external environment * Proprioceptors report the positions of skeletal muscles and joints
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15_LectureOutline - Sensory Information Afferent Division...

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