MODULE 6- ARPIN STUDY GUIDE Flashcards
different parts of the retina
-macula (fovea)
-optic disc (blind spot)
different types of neurons in the retina (5)
-photoreceptors (rods + cones)
-bipolar cells
-ganglion cells
-horizontal cells
-amacrine cells
direct path of light
photoreceptors (rods/cones) ->
bipolar cells->
ganglion cells
what makes the optic nerve
axons of ganglion cells
horizontal connections
-horizontal cells
-amacrine cells
^make horizontal connections between photoreceptors/ganglion cells
photoreceptors depolarize/hyperpolarize to light
hyperpolarize
do photoreceptors have APs
no
membrane potential response to light intensities is ____
graded
electrical activity of photoreceptors is depends on what 2 types of channels
-K+ channels
-cGMP-gated Na+/Ca2+ channels
K+ channels are always open/closed
open
steps in phototransduction
light stimulus ->
absorption of photos leads to decrease in cGMP levels ->
closing of Na/Ca channels (gated by cGMP) ->
reduction of Na+/Ca+ influx ->
receptor hyperpolarization
dark- photoreceptors membrane potential
~40mV
-due to Na+ and Ca2+ influx which acts to depolarize and K+ efflux which acts to hyperpolarize
light- what happens to photoreceptors
hyperpolarize
-due to reduced Ca+/Ca2+ influx and continued K+ efflux
rods/cones have greater sensitivity to low light intensity
rods
response in rods do what in bright conditions
saturate
cones
response to 3 different wavelengths of light -> color vision
are there rods/cones on fovea
lots of cones
-no rods