视力的灵敏程度影响色觉.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,Colour Vision,Sensitivity&Acuity,Colour Vision,Trichromatic,theory of colour vision,There is only one type of rod and this responds strongly to bluish-green light,Cones are divided into three categories,each of which has a different,sensitivity,to light,There are red light receptors,green light receptors and blue light receptors.,These cone sensitivities support the,trichromatic,theory as all colours of the visible spectrum can be seen by mixing the 3 primary colours(red,blue and green),White objects reflect all colours to eye,black absorbs all colours so no light to the eye.,of light absorbed by different cones,Colour Blindness,If you have normal vision you will see a figure seven in reddish brown dots.,People with red-green colour blindness will not see the 7,why?,These people lack red sensitive cones,but the green stimulated cones are stimulated by the red light,so all dots appear green,Sensitivity and Acuity,Rods and cones synapse with bipolar cells,Bipolar cells synapse with ganglion cells,Ganglion cells synapse with neurone fibres,At the fovea each cone synapses individually with a ganglion cell,This gives good Acuity(resolution).N.B Bright light needed,Many Rods synapse with one bipolar neurone RETINAL CONVERGENCE,Dim light results in small amount of neurotransmitter release,Individually,this would be insufficient to over come the,threshold,of the bipolar cell,but the total amount of transmitter from several rods is,This gives less,acuity,but better,sensitivity,