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Special Scenses
| Question | Answer |
|---|---|
| Myopia | nearsightedness; focal point is in front of the retina, ex. in a longer than normal eyeball |
| hyperopia | farsightedness; focal point is behind the retina, ex. in a shorter than normal eyeball |
| astigmatism | caused by unequal curvatures in different parts of the cornea or lens |
| presbyobia | loss of near vision with age due to lens becoming more dense and less flexible with age |
| caratacts | clouding of lens due to aging, diabetes mellitus, heavy smoking, and frequent exposure to intense sunlight |
| lens fibers | cells filled with the transparent protein crystallin |
| pigmented layer of retina | pigmented, outer layer, absorbs light and prevents its scattering, stores vitamin a |
| neural layer of retina | photoreceptor; transduce light energy |
| cells that transmit and process signals in neural layer | bipolar cells, ganglion cells, amacrine cells, and horizontal cells |
| photopigments | visual pigments in outer segments of rods and cones that change shape as they absorb light |
| rods | numerous in peripheral region of retina, operate in dim light, provide indistinct, fuzzy, non color peripheral vision |
| cones | in macula lutea; concentrated in fovea centralis, operate in bright light, provide high acuity color vision |
| rhodospin | visual pigment in rods, embedded in the membrane that forms discs in outer segment |
| color blindness | due to cogenital lack of one or more of the cone types (blue, green, and red) |
| phototransduction (dark) | cGMP binds to and opens cation channels in the outer segments of photoreceptor cells (Na and Ca influx creates a depolarizing dark potential of about -40 mV) |
| phototransduction (light) | light activated rhodopsin activates a g protein, transducin; activates PDE; hydrolyzes cGMP to GMP and releases from Na channels. w/o cGmp, Na channels close and membrane hyperpolarizes to about -70 mV |
| depth perception | both eyes view the same image from slightly different angles; results from cortical fusion of slightly different images |
| lateral geniculate nuclei of thalamus | relay info on movement, segregate the retinal axons in preparation for depth perception, emphasize visual inputs from regions of high cone density, sharpen contrast info |
| what are the two areas of the visual cortex? | striate cortex (primary), prestriate cortex (association area) |
| temporal lobe (vision) | processes identification of objects |
| parietal cortex and postcentral gyrus (vision) | process spatial location |
| blindness | caused by lesions in key components of the eye or in the brain |
| striate cortex | primary visual cortex; processes contrast information and object orientation |
| prestriate cortices | visual association areas; processes form color, and motion input from striate cortex |
| olfaction | taste and smell |
| chemical senses | chemoreceptors respond to chemicals in aqueous solution |
| olfactory pathway | olfactory receptor cells synapse with mitral cells in glomeruli of olfactory bulbs; mitril cells amplify, refine, and relay signals along tracts to the olfactory cortex, hypothalamus, amygdala, and limbic system |
| what papillae are associated with taste buds? | fungiform, foliate, and circumvallate papillae |
| structure of a taste bud | basal cells (dynamic stem cells) gustatory cells (taste cells) microvilli (gustatory hairs) project through taste pore to surface |
| what are the five basic taste sensations? | sweet(sugars, saccharin, alcohol,and some amino acids, sour (hydrogen ions), salt (metal ions), bitter (alkaloids quinine and nicotine), umami(glutamate and aspartate) |
| bony labyrinth | tortuous channels in temporal bone; three parts : vestibule, semicircular canals, cochlea |
| helicotrema (apex) | where scalae tympani and vestibuli are continuous |
| bending of stereocilia | opens mechanicaly gated ion channels. inward K and Ca current causes a graded potential and the release of neurotransmitter glutamate; cochlear fibers transmit impulses to the brain |
| localization of sound | depends on relative intensity and relative timing of sound waves reaching both ears |
| conduction deafness | blocked sound conduction to the fluids of the internal ear; can result from impacted earwax, perforated eardrum, or otosclerosis of ossicles |
| sensorineural deafness | damage to neural structures at any point from cochlear hair cells to auditory cortical cells |
| tinnitus | ringing or clicking sound in the ears in the absence of auditory stimuli; due to cochlear nerve degeneration, inflammation of middle or internal ears, side effects of aspirin |
| menieres syndrome | labyrinth disorder that affects the cochlea and semicircular canals; causes vertigo, nausea, and vomiting |
| vestibular receptors monitor? | static equilibrium |
| semicircular canal receptors monitor? | dynamic equilibrium |
| crista ampullaris | sensory receptor for dynamic equilibrium; one in the ampulla of each semicircular canal; major stimuli are rotatory movements |
| bending hairs in cristae causes | depolarizations, rapid impulses reach brain at faster rate |
| bending of hairs in opposite direction in cristae causes | hyperpolarizations and fewer impules reach the brain |
| input for balance and orientation | vestibular receptors, visual receptors, somatic receptors |
| hyperopic | seeing only gray tones, as in babies after birth |
Created by:
hberglund
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