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Sensory receptor
specialized cell or cell process that provides info abt conditions inside or outside body, characteristic of sensitivity and range
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General senses
- Free nerve endings = simplest receptors
- sensations arrive at somatosensory cortex
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Special senses (5) - smell, taste, balance, hearing, vision
- structurally more complex
- receptors - located in complex sense organs
- sensations - arrive at specific area of cerebral cortex
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Phasic receptors (fast-adapting receptor)
- inactive, provide info on intensity and rate of change of stimulus
- touch,pressure and smell (central adaptation)
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Tonic receptors (slow-adapting receptor)
- always active, little adaptation
- Photoreceptors of eye, proprioceptors (body position)
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Nociceptors (general senses)
- pain, tissue damage
- free nerve ending - large receptive fields
- 3 types - extremes of temperature; mechanical damage; dissolved chemicals
- referred pain - visceral pain sensation perceived as originating in superficial regions inervated by same spinal nerve
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Thermoreceptors (general senses)
- temperature change
- free nerve endings
- 4 times more cold receptors than warm
- Phasic receptors - rate of change and intensity
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Mechanoreceptor (general sense)
- contact or pressure
- stimuli stretch, compress, twist, distort cell membranes
- tactile - touch, pressure, vibration
- lamillated corpuscle
- baroreceptor - pressure change
- blood vessels, stretch receptors, hollow organs
- proprioceptor - position of joints and muscles
- muscle spindle and golgi tendons
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Chemoreceptors (general sense)
chemical composition of body fluids
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olfaction (smell)
(special sense)
Olfactory epithelium - cover inferior side of cribiform plate, conchae and septum
- Organs:
- olfactory receptor cells- modified neuron
- basal cells - stem cells
- thick mucus - olfactory glands = Bowman's glands
- pathway:
- receptors to O. nerve to O. bulbs to O. tract to O. cortex
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Gustation (taste)
taste/gustatory receptors - taste buds resided on sides of papillae
- 3 types of gustatory cells
- taste hairs (microvilli)
- taste pore
- salivary juice
Facial, Glossopharyngeal, vagus to thalamus to Gustatory cortex
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4 primary taste sensation
- sweet, salt, sour, bitter
- umami - amino acids
- water - water receptors
threshold stimulation varies (survival value)
olfactory organs role in taste perception
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Equilibrium and hearing
External ear - external acoustic metas to tympanic membrane
middle ear - 3 auditory ossicles
Inner ear - 3 sensory organs for equilibrium and hearing
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