eyes etc Flashcards
where is the highest concentration of cones located
in the fovea of the retina
where is the highest concentration of rods located
at the edges of the eye
describe spacial summation
- for rods
-the stimulation of several impulses to one bipolar neurone at once
-means that threshold is more likely to be reached - and an action potential will be reached
what are rods described as having
-high visual sensitivity
-low visual acuity
what are cones said to have
-low visual sensitivity
-high visual acuity
when are rods used
in dim light
when are cones used
bright light
-for colours
why do cones have high visual acuity
because they dont have spacial summation
- most cones synapse with only one bipolar neurone
-a separate set of impulses is sent to the brain
what does it mean for cones to have a high visual acuity
-provides a no blurring affect
why and what ratio do cones have
1:1
-each part of an image is being detected by a different cell
what does it mean for rods to have low visual acuity
-they share a bipolar neurone
-several rods may be stimulated
-so the brain only receives one set of impulses from a large information
why do rods have high visual sensitivity
-rhdopsin is broken down at lower light intensities
-several rods synapse with one bipolar neurone
-meaning threshold is more likely to be reached
The fovea of the eye of an eagle has a high density of cones. An eagle focuses the image
of its prey onto the fovea.
Explain how the fovea enables an eagle to see its prey in detail.
Do not refer to colour vision in your answer.
-Cones have high visual acuity
-single cone connected to
bipolar neurone
-single impulse sent to the brain
The retina of an owl has a high density of rod cells.
Explain how this enables an owl to hunt its prey at night.
Do not refer to rhodopsin in your answer.
-rods have high sensitivity to light
-multiple rods connected to one neurone
-spatial summation occurs to overcome threshold
