ColourVisionSensitivity&AcuityColourVisionTrichromatictheoryofcolourvision•Thereisonlyonetypeofrodandthisrespondsstronglytobluish-greenlight•Conesaredividedintothreecategories,eachofwhichhasadifferentsensitivitytolight•Thereareredlightreceptors,greenlightreceptorsandbluelightreceptors.•Theseconesensitivitiessupportthetrichromatictheoryasallcoloursofthevisiblespectrumcanbeseenbymixingthe3primarycolours(red,blueandgreen)•Whiteobjectsreflectallcolourstoeye,blackabsorbsallcolourssonolighttotheeye.http://www.tdzl.net/http://www.u51688.com/WavelengthsoflightabsorbedbydifferentconesColourBlindness•Ifyouhavenormalvisionyouwillseeafigureseveninreddishbrowndots.•Peoplewithred-greencolourblindnesswillnotseethe7,why?•Thesepeoplelackredsensitivecones,butthegreenstimulatedconesarestimulatedbytheredlight,soalldotsappeargreenSensitivityandAcuity•Rodsandconessynapsewithbipolarcells•Bipolarcellssynapsewithganglioncells•Ganglioncellssynapsewithneuronefibres•Atthefoveaeachconesynapsesindividuallywithaganglioncell•ThisgivesgoodAcuity(resolution).N.BBrightlightneeded•ManyRodssynapsewithonebipolarneurone–RETINALCONVERGENCE•Dimlightresultsinsmallamountofneurotransmitterrelease•Individually,thiswouldbeinsufficienttoovercomethethresholdofthebipolarcell,butthetotalamountoftransmitterfromseveralrodsis•Thisgiveslessacuitybutbettersensitivity
