eyes p2 Flashcards
what are the colours that are detected by the cones
red
green
blue
waht does each cone contain
only one pigment called iodopsin
what does each pigment have
its own absorption peak at a particular wavelength of light
blue-420
green-550
red-560
where is most light absorbed
-at the absorption peak
where is less light absorbed
at wavelengths other than the absorption peak
what happens when a cone absorbs more light
-produces a greater frequency of impulses
what does the brain do
-recieves impulses from the different types of cone and the colour perceived is determined by the frequency o impulses of each cone type
what to call the colours
blue/red/green sensitive
describe and explain the visual acuity of rods
low visual acuity
-they share one bipolar neurone so impulses are going to a single neurone meaning more likely to be blurred
describe and explain the visual sensitivity of rods
-rods have a high visual sensitivity as they contain the photosensitive pigment rhodopsin that is broken down at lower light intensities than iodopsinn
-several rods synapse with one bipolar neurone
-spacial summation takes place -the combined stimulation of several rods next to each other enables the threshold value to be reached .
describe the visual sensitivity of cones
they have a low visual sensitivity as they have a 1:1 relationship with a bipolar neuroen so no spatial summation occurs
-so threshold is less likely to be reached at low light intensities
-so cones dont generate impulses along bipolar neurone
describe the visual acuity of cones
cones have a high visual acuity
-whihc provides a no blurring effect
-they dont have spacial summation ,
-cones synapse with only one bipolar neurone - several separate sets of impulses are sent to the brain at different times
where are the most cones located
I the fovea
