Sensory systems - Sensory receptors: Keeping in touch with...

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Sensory receptors: Keeping in touch with our world!
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Winetasters Wheel ‘o Flavors Sensory receptors can discriminate a remarkably large number of traits associated with taste and smell…it’s a matter of training the brain to distinguish odors and tastes within complex mixtures. This chart reflects the major attributes for distinguishing characteristics of wine.
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Sensory Basic Functions Transduction: convert stimulus into nerve impulses (APs) Amplification: increase the stimulus energy so it is readily perceptible (e.g. photons have much less energy than resulting APs) Transmission: transmit APs to specific brain region for interpretation Integration: sensory adaptation to chronic stimuli (elimination of excess “noise” to CNS)
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Proportional response to stimulus Muscle Dendrites Stretch receptor Axon Membrane potential (mV) –50 –70 0 –70 0 1 2 3 4 5 6 7 Time (sec) Action potentials Receptor potential Weak muscle stretch –50 –70 0 –70 0 1 2 3 4 5 6 7 Time (sec) Strong muscle stretch The frequency of APs is proportional to distance between the dendrites attached to the muscle cell. Thus, the CNS receives constant inputs on the length of stretch in the muscle
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Directional specificity –50 –70 0 –70 0 1 2 3 4 5 6 7 Time (sec) Action potentials No fluid movement –50 –70 0 –70 0 1 2 3 4 5 6 7 Time (sec) Receptor potential Fluid moving in one direction –50 –70 0 –70 0 1 2 3 4 5 6 7 Time (sec) Fluid moving in other direction Membrane potential (mV) “Hairs” of hair cell Neuro- trans- mitter at synapse Axon Less neuro- trans- mitter More neuro- trans- mitter When cilia are bent in one direction, AP frequency increases. When bent in the opposite direction AP frequency decreases. Thus CNS receives information on both the magnitude and direction of the stimulus.
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Basic receptor types: 1. Chemoreceptors (respond to chemicals) 2. Mechanoreceptors (Proprioreceptors) (respond to motion or displacement) 3. Baroreceptors (respond to changes in pressure) 4. Photoreceptors 5. Thermal receptors 6. Electromagnetic receptors
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Cutaneous receptors Quite a variety: Pressure Important because Touch skin is in direct Vibration contact with the Tickle physical world! Thermal (environment) Pain
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Vestibulocochlear System The senses of hearing (cochlear system) and balance (vestibular system) are both linked together and are based on a system containing: Hair cells (receptors), and Endolymph
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Hearing The collection, transmission and perception of sound occurs, respectively, in the: Outer ear (collection) Middle ear (transmission) Inner ear (perception)
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Basic ear anatomy Pinna Auditory canal Eustachian tube Tympanic membrane Outer ear Middle ear Inner ear
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Estimate return to normal function no earlier than Wed afternoon
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Sensory systems - Sensory receptors: Keeping in touch with...

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