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Get the Sensation! Aps reaching the brain via sensory neurons are sensations Interpretation of the sensation by the brain is perception

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Presentation on theme: "Get the Sensation! Aps reaching the brain via sensory neurons are sensations Interpretation of the sensation by the brain is perception"— Presentation transcript:

1 Get the Sensation! Aps reaching the brain via sensory neurons are sensations Interpretation of the sensation by the brain is perception ibits.html getstarted

2 Some facts…….  Aps are the same no matter what type of stimulus causes them  Sensory receptors stimulate Aps by converting energy to an AP-this is sensory transduction  The ability to distinguish these Aps depends on what part of the brain receives them  The transduction threshold varies with conditions & genetics

3 Steps in Sensory Transduction 

4 Sensory Systems  Sensory receptors are neurons specialized to detect a stimulus  Categorized based on the type of stimulus they respond to Mechanoreceptors-movement, pressure, tension Mechanoreceptors-movement, pressure, tension Skin, ears, nociceptors in jointsSkin, ears, nociceptors in joints Photoreceptors-variations in light Photoreceptors-variations in light eyeeye Chemoreceptors-chemicals Chemoreceptors-chemicals Nose, tongueNose, tongue Thermo receptors-changes in temp Thermo receptors-changes in temp Hypothalamus,skinHypothalamus,skin Pain receptors-tissue damage Pain receptors-tissue damage Throughout bodyThroughout body Electromagnetic receptors Electromagnetic receptors Visible light, electricity, magnetismVisible light, electricity, magnetism

5 Photoreceptors  Eye cups/eye spots Intensity/location of light Intensity/location of light  Invertebrate eyes Compound eyes-insects & crustaceans Compound eyes-insects & crustaceans Each eye consists of several thousand ommatidiaEach eye consists of several thousand ommatidia Mosaic image, extremely good at detecting movement & colorMosaic image, extremely good at detecting movement & color Single-lens eyes- spiders, mollusks Single-lens eyes- spiders, mollusks Similar to cameraSimilar to camera

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8 Vertebrate Eye  Sclera-thick, protective outer layer, connective tissue Becomes transparent cornea in front of eye, allows light in Becomes transparent cornea in front of eye, allows light in Conjunctiva(mucous membrane) covers sclera & keeps eye moist-doesn’t cover cornea Conjunctiva(mucous membrane) covers sclera & keeps eye moist-doesn’t cover cornea  Choroid-layer just underneath sclera Pigmented, forms iris in front of eye Pigmented, forms iris in front of eye Hole in center of iris is pupil-iris controls amount of light entering pupil Hole in center of iris is pupil-iris controls amount of light entering pupil Highly vascularized Highly vascularized

9 Vert. Eye cont…  Retina-just inside choroid-innermost layer Contains photoreceptor cells(rods & cones) Contains photoreceptor cells(rods & cones) All rods & cones connect to optic disc at back of retina which carries impulse to brain All rods & cones connect to optic disc at back of retina which carries impulse to brain No photoreceptor cells here-blind spotNo photoreceptor cells here-blind spot  Lens & ciliary body- Lens transparent protein disc that focuses images by changing shape Lens transparent protein disc that focuses images by changing shape Flat for close objects, spherical for distant objectsFlat for close objects, spherical for distant objects Ciliary muscles control shape of lens Ciliary muscles control shape of lens  Aqueous humor-fluid between cornea & lens  Vitreous humor-fluid behind lens-fills most of eye 

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12 Photoreceptor cells  Rods More sensitive to light, no color distinction More sensitive to light, no color distinction Night vision, black & white Night vision, black & white Fovea-area of retina w/ greatest density of rods Fovea-area of retina w/ greatest density of rods  Cones Need more light to be stimulated, excellent color distinction Need more light to be stimulated, excellent color distinction Day vision Day vision  Relative numbers differ in nocturnal & diurnal animals  Rhodopsin Visual pigment in rods & cones Visual pigment in rods & cones Consists of retinal pigment & opsin proteinConsists of retinal pigment & opsin protein Light triggers a shape change responsible for generating action potentialLight triggers a shape change responsible for generating action potential

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15 Mechanoreceptors-Hearing

16  The ear converts mechanical energy into electrochemical energy of action potential(mechanoreceptors)  External ear(pinna)-collects sound waves  Tympanic membrane(ear drum)-transmits vibrations to middle ear bones  Vibrations are passed to incus(anvil), then malleus(hammer), then stapes(stirrup), which transmits them to oval window

17  Oval window transmits to cochlea, which contains fluid and the organ of corti, with tiny hair cells embedded in it  As fluid of cochlea moves, hair cells tap against tectorial membrane-this causes an action potential to be generated which is transmitted to auditory nerve  Auditory nerve carries AP to temporal lobe of brain

18  Volume of sound is determined by amplitude (height) of sound wave Louder sound = more vibrations =more Aps Louder sound = more vibrations =more Aps  Pitch is determined by frequency of the waves Higher frequency = higher-pitched sound Higher frequency = higher-pitched sound

19 Balance  Detected by mechanoreceptors(hair cell) in the inner ear

20 Balance  Utricle and saccule detect head position using calcium crystals, hair cells, and gravity

21 Semicircular canals detect head movement using fluid and hair cells

22 Taste and Smell  Both taste buds and olfactory cells (nose) are chemoreceptors


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