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20 Cards in this Set
- Front
- Back
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Sensory Organ Functions |
Reception °Stimulation of membrane receptor channel proteins →Mechanical →Chemical →Electrical °Light - photoreceptors Transduction °Channels open – ions influx/efflux (photoreceptors close channels) °Membranes depolarizes or repolarizes Perception: processing of information in cerebrum |
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Modification of Stimulus in CNS |
°Precessing →Receptor cell: strength of stimulus (number of signals per transmitter + number of transmitter per receptor cell) °Amplification →Signal transduction pathways amplify response to one stimulus within one neuron →A single stimulus activates many neutrons in 1 neural pathway °Sensory adaptation → Continued stimulation decreases the response by the receptor cell |
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Sensory Receptors |
°Photoreceptors (vision – retina) →Pigments : rhodopsin (rods) & photopsin (cones) °Mechanoreceptors (movement of cytoskeleton) →Touche & pressure – skin; proprioception – ligaments, tendons & mus- cles; stretch receptors – blood vessels →Mechanoreceptor channels: hearing & balance – cilia in cochlea & vestibule °Chemoreceptors (chemicals) →Olfaction (nasopharynx); taste (tongue, papillae) |
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Sensory Receptors (cont'd) |
°Nociceptors (pain; extreme temperature or pressure) →Free nerve endings →Skin, mouth, tongue, internal °Thermoreceptors (temperature & certain chemicals) →Skin, mouth & tongue →Capsaicin: detects hot & spicy food →Menthol: detects cool & minty food °Osmoreceptors (blood osmolarity) →linked to hypothalamus: thirst center & release of ADH |
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Anatomy of the Eye |
Conjunctiva: mucous membrane that lines the eyelid Sclera: under conjunctiva – connective tissue; white of the eye Choroid: thin pigmented layer, heavily vascularized Cornea: transparent bulge of the sclera Iris: continuation of the choroid beneath the cornea Pupil: "iris diaphragm", controls amount of light that goes into eye parasympathetic & sympathetic control Lens: focuses light on retina, image is horizontally & vertically flipped Ciliary body: contains muscles to shape lens; produces the aqueous hu- mour |
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Anatomy of the Eye (cont'd) |
Retina: contains photoreceptor cells rods for light intensity and cones for colour neutrons process the visual information Fovea: center of visual field (only cones); located in macula Humours: fluid/gel-filled cavities Aqueous (anterior chamber) Vitrious (posterior chamber) |
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Pathway of Information; Rods & Cones |
Pathway: Rods/Cones → Horizontal and/or bipolar cell → amacrine & ganglion cells → optic nerve → visual cortex (through RAS & thalamus) Rods: dim light perception – night vision Cones: colour perception – highest density in fovea |
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Visual cycle |
°Reception: rods & cones (photoreceptors) →Pigment: rhodopsin/photopsin: opsin (protein) + retinal (vit. A) →Light activated isomerization of retinal (cis → trans) →Detachment from opsin →Enzymatic reactivation (trans → cis) & rejoining with opsin °Transduction → G-protein (phosphodiesterase): cGMP → GMP – closes Na+ channels °Response: →Hyperpolarisation of membrane →Neurotransmitter glutamate is topped |
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Visual Processing in Retina |
°Bipolar cells →Go from hyper- to depolarized or vice-versa °Horizontal & amacrine cells →Integration of visual information →Lateral inhibition – enhance contrast & sharpness; bright spot appears brighter because neighbouring cells are inhibited °Ganglion cells →Each responds to activation/inhibition by bipolar cells →Each receives information from many rods/cones – fields →The smaller the number of rods/cones per cell, the smaller the field, the better the resolution |
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Visual Processing in Nervous System |
°Optic chiasma →Separates left & right visual field information: 3D vision °Visual cortex (30% of cerebral cortex) →Straightening the image →3D vision →Integration of information & understanding |
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Anatomy of the Ear |
°Outer ear →Auricle/pinna, auditory canal & tympanic membrane °Middle ear →Malleus, incus & stapes – oval window →Part of Eustachian tube – pressure equalizer & mucus drainage |
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Anatomy of the Ear (cont'd) |
°Inner ear →Fluid-filled semi-circular canals, vestibule: balance (position of head) & movement →Cochlea °Vestibular canal °Tympanic canal °Cochlear duct with Organ of Conti →Basilar membrane (moves with sound waves) →Hair cells – linked with axons of sensory neutrons →Tectorial plate |
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Pathway of Soundwaves |
°Air pressure wave in auditory canal °Tympanic membrane vibrations °Ossicles: Malleus, incus, stapes vibrations °Cochlea: oval window vibration → perilymph pressure waves in vestibular canal |
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Pathway of Soundwaves (cont'd) |
°Organ of Conti →Vibrations of basilar membrane °Specific positions according to frequency (pitch) °Different amplitudes according to intensity (volume) →Bending of hair cells in different direction relative to fixed tectorial plate →Change in action potential firing patterns by connected icons of senso- ry neurons of auditory nerve →Propagation of action potential to CNS through thalamus °Pressure waves return to round window by tympanic canal °Dissipation of pressure waves |
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Equilibrium: Vestibule |
°Perception of position (head) & linear acceleration °Utricle & saccule: chambers covered in hair cells →Hair cells embedded in gel with calcium carbonate particles – otoliths →Movement of head up/down, movement of body during sideways or vertical acceleration →Causes otoliths to bed hair cells →Sensory output dependent on position of "hairs" |
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Equilibrium: Semicircular Canals |
°Perception of angular/rotational acceleration °3 canals in 3 planes: x, y, z °At base of canals: chambers covered in hair cells →Hair cells embedded in cupula →Rotation of head causes perilymph to press against cupula →Sensory output dependent on position of hairs |
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Olfaction: Nasopharynx |
°Olfactory epithelium: receptors embedded throughout the membrane →Each olfactory receptor has one chemoreceptor type (300-1000 total) →Binds to different groups on more than one compound →Each odorant activates a specific combination of chemoreceptors →Each short axon/synapse activates one type of bulb neuron °Olfactory glands secrete mucus |
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Olfaction: Brain |
°Olfactory bulb (cell bodies) →For each odorant, a specific pattern of olfactory bulb neutrons get acti- vated °Olfactory tract (neuron axons) °Connects with limbic system & primary olfactory area |
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Gustation: Tastants |
°Binds to specific receptors °Sweet – sugars; size, shape & chemical groups vary °Sour – acids °Salty °Bitter – caffeine, quinine; size, shape & chemical groups vary °Umami (savoury) – amino acid glutamate °Hot/spicy & cool/minty |
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Gustation: Papillae |
°Located on tongue °Cluster of tastebuds →Many sensory receptor cells found in a single taste bud →Each sensory receptor is specific to a type of tasting →All tastants can be detected by a single taste bud →Sensory neutrons carry information to primary taste area via thalamus |
