Visual system Dr. Clery Flashcards
what 2 thalamic nuclei are involved in vision?
pulvinar, lateral geniculate nucleus
what do the cornea and the lens do? which one can accomodate?
refract light; lens can accomodate (move)
what controls the lens shape?
ciliary muscles
what is myopia?
nearsighted = far away images are blurry (eyeball is too long)
what is hypermetropia?
farsighted = close objects are blurry (eyeball too short / hyperopic)
what is astigmatism?
the lens or cornea are not spherical
what is presbyiopoa?
lens gets stiff and is unable to accomodate for near vision
what is cataract?
change in the lens color
LAYERS OF THE RETINA
- pigment epithelium
- photoreceptor outer segments
- outer nuclear layer
- outer plexiform layer
- inner nuclear layer
- inner plexiform layer
- ganglion cell layer
- nerve fiber layer
are there more rods or cones photoreceptors?
20x more rods than cones
what is the pathway of light
light -> photoreceptors -> electrical signal -> bipolar cells -> ganglion cells -> brain
what causes blurry vision?
different points from a same object on the retina
what are rods vs cones sensitive to?
rods are highly sensitive to light
cones are sensitive to color and shapes
rods and cones: which on is for night vision?
rods because they are most sensitive to light
how are photoreceptors in the dark?
depolarized
how do photoreceptors act in the dark?
produce a constant flow of neurotransmitter release onto bipolar cells
what value is the resting potential
-40mv
how are photoreceptors cGMP levels at rest?
high
what happens when light shines on the photoreceptor
Na+ channels close, K+ channels stay open -> photoreceptor becomes hyperpolarized
name the order the the cells that light hits first
ganglion cell, amacrine cell, bipolar cell, horizontal cell, photoreceptors
rods or cones: which is used for peripheral vision vs foveal vision?
peripheral vision = rods
foveal vision = cones
rods or cones: which function in scotopic vs photopic vision?
scotopic = rods
photopic = cones
can rods see color?
no
are rods or cones saturated in daylight?
rods because they are highly sensitive to light