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PSY280 JULY 10.docx

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PSY280 JULY 10, 2012 Idenetify the properties of light Anatomical prop of the eye How eye convert light energy into electrical energy Is it indirect – way we see light is exactly reciprocal – vision is indirect Percept process - One electicity stim - Next elect - Thrird exerpience and action - Any sensory perception, what is encoded is different - Vision stimulus is light – light that is reflected off objects not direct llight - Electricity – how light converted into neural signal use rod and cones - Experience and action – as ganglia exit and into brain and experience an action - Create rep of image and respond to it Elec mag spectrum - All energy that can be given off or absorbed by particles - Short wave to long gamma to radio/tv waves - What visual system can process is very small fragment of – 400 and 700 nm, - Wach wavelength rep in brain as colours, short ev blue, med green and yellow, long is red - Brain interpret wavelength as colour – this is indirect not see colour interpret it from different wavelength - Way 400 – 700 light from sun and falls to earth fall in to this band - Uv get absorbed ozone and radio beed medium to travel in What is light - Light - Differ – duel theory of light – prop in two way - Wave length – how light travels it travels as waves – waves from sun - Particle light – amount of energy releaseaed - energy is considered particles and interacts with other - Photon is smallest unit of light - Light packs or photons Contd - Wavelength as wave or photon - Wve peak from peak - Short sv short distance from peaks - Pphotons – energy released from atoms to produce light - Jump to higher electrons – go down release energy and energy released in form of photon Wv and photon - Mus t be rlelaltard - More energy it has shoetrer ewavelenght - Blue more wv larger energy and red less energy - E = hc / wqvelength inverse relationships - Smaller energy is longer eavelenght - Blue wv length blue more energy then red wavelength Light properties - Light perceive reflected off objects - Dif ways light bounced off - Opaque mirroe or wood block or table – light cannot transmit through hit and bounced off or absorbed – in sun becomes hot – light becomes heat - Bc transmitted – goes through travels through medium glass water or air – smooth like glass transmitted same way it came in – however jagged and curved light then transmitted and refracted bend or switvch direction Ref - In transparent surfaces - Bending of light from one medium to another - Lenese dif refraction - Concave inward diverges out relative to optic axis – imaginary line connects - Concave divergence out optic axis and conves outward and light converges in middle - Loacation different levels of refraction Contd - Object distance ffect image distance - Straight lines optical infinity directly into paraleld - Move closer andgle of light switches not optic infinity object image - moves further away contd - same point in eye change curvature of lens – further away flatter – bring closer to lens increase curvature – object still falls same distance bc refractory power larger more convergence and smaller image distance – controls where on retina the eye - outside in - crnea – located on top of iris and pupil – size of contact lens – clear to be transparent – no blood vessels but nerve ending for tears to help regeneration of fibers – scratch fine within 24hrs - behind cornea aqueous humor – liquid stems from blod nutrients and extract waste from cornea - underneath aqauaue humor – iris and pupil – iris is muscle and space has hole and hole is pupil black area – pupil allow light in control amount of light into eye - iris is coloured bc pigmented and everyones is different bc milininn and everyone with diff con and sustansia nigra is coloured - inside is lens clear and controlled by cillary bodies muscles flatten or curve it - behin lens is virtus humor all area retina is made of blood nutrients and extracts waste from eye – consistency of egg white - after have retina or fovia – thin band of neurons photo recpeotors and one spot back of fovea best viusla acuity – clearness - back of eye blindspot – all axons of ganglia cell exit and form optic nerve - then sclera – same substance dura mater meade up in brain – eye is mini brain - nutrients brought in between retina and epthimela brings in nutrients below coroid vein dilation - bright light pupil small so much not over load retina constricts less light - large dilate more light in – doctors dilate to better look eye optic prop - cornea 80 percent refractive rest is by lens - both are curved structure allow light into high - cornea is fixed - curvature is by lens – called accomdation – changes curvature to focus images on retina – related greater refraction from air to cornea and to lens acco - far away lens thin and long by cilary bodies – they relax and ligmanets tighten and cuases lens thin and more flat - closer – cilary muscles constrict cuase lig to be lose and push lens fatter and shorter - differences in pupil – distant more like enlarge pupil - close constrict pupil contd - near and far point - near point only as much as can before focus - in focus is 20 cm closer is blurry is blurry – max accom for object near - far point – max lens can flatten anything past is blurry - near bulge and far flat lens problems - myopia good near sight problem far – reason eyeball to short or lens to bulge or cornea to big not far on retina but infront falls short - muscles not working always relaxed - how correct – use negative lens – concave lens – diverges light away from object axis falls short so converge later on, amount divergence is perspricebd by test very little or a lot contd - hyper far away not close - eyeball to short – cornea or lens to flat or too thin falls behind retina – close is blury – cprrect is positive lense – convex lens – increases what lens would do, so elongate it – older have positive and younger is myopia contd - presbyopia – sim to hyper dif casue - near objects blurry – lens diff to accomadate hardens as ones ages – lens is hard – doesn’t bulge stays thin lasik - cant corrct for prespyobia bc related to lens other types is eyeball - lasik reform cornea - myopia to flatten it shorten eye lenft - hyper lengthen it thicken make it longer - astigmatism no tsmooth bumps or off spherical improve by lasik smooth it out surgey video - bupa animation - myopia too curved clse clear falls short - hyperopia cornea to flat beyond retina and bluured for near and far, from edge then center opp for other more center - astigmatism uneven – local anesthistic applied drops or injection – frame prevents blinking and make flap and laser shape cornea – seals within minuted and eye drops prevent infection cataracts - lens becomes opaque – lens needs to be clear - abnormal build up of molecules and gets rusted - bluured vision across visual field - casue numerous – aging, tramau, heredity congential cataracts, light not get into eye identify have to get surgey bc visual paths in brain tuned early on to visual input – no access visual info to eye and brain may become blind rest of life and metabolic disorders - surgey – to have lens replaces like lasik cut eye and replace lens with arti ficial one made of plastic rephrase - refractive surfaces – lens for all same refractive power closer in converge further away, change angle change asngel, lens shape is refrtartive power - near point and far point – near is closest without blurry, and far is farest without blurry closer or further is blury the retina - main - retina is band of neurons or cells - awakarlfy contrcuted - photo receptios located at deepest layer, pass through all layer of retina to phot receptor, reason is bc all layers is clear, behind phot is epithemal layer – pigmented not clear and absorb light – so light not bouncing off and interferes, not captured by photo receptors coapture by pigmented pauqe epithemial layer phot - rodes and cones bc shape - cones conical shape and pointed - rode more spherical and elongated - dualplex bc to types to photo repect - some only rodes night vison rats - and cones bc day and color vsion lzards - humans 2 duplex - converted light energy to neural signal - and done in outer layer or photo receprts and base od retina or furtehs part trans - how convert - other seg disks and thousands of visual pigment and contain oxin protein and molecule reninal - photon in, pigment capture and rentinal stick up and separate from oxcin and break down and called isomeration, absorb photon and retinal spe from pxin and
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