Retina

Question 1

what kind of vision is rod mediated? cone mediated? both?

Answer 1

scotopic, photopic, mesopic

Question 2

the glial cells of the retina are

Answer 2

muller cells. RPE also phagocytizes old discs and regenerates chromophores

Question 3

describe phototransduction

Answer 3

11cis retinal in discs is isomerized to all-trans which activates rhodopsin. Gcoupled receptor. cGMP is hydrolized & cGMP-gated Na/Ca channel closes, hyperpolarizing the cell

Question 4

describe resting and light-stimulated state of PRs. Describe response intensity

Answer 4

depolarized in dark. hyperpolarized in light by Na channel closure. Graded intensity

Question 5

where are photopigments regenerated? what does this mean for retinal detachment

Answer 5

RPE (rhodopsin), muller cells (cone opsin). Detachment results in loss of pigment regen, phagocytosis, and oxigen

Question 6

wavelength absorbed by cone opsins

Answer 6

430 (blue)- 560 (red)

Question 7

the fovea contains

Answer 7

red and green cones; not blue cones or rods

Question 8

midget pathway

Answer 8

one cone contacts one on and one off bipolar cell which contact one on and off ganglion cells

Question 9

off bipolar cells receive what type of synapse? on bipolar cells?

Answer 9

off-sign conserving. On-sign inverting (hyperpolarization of cone=depolarization of bipolar cell)

Question 10

when do off ganglion cells produce spikes?

Answer 10

at light-off. Two types make shadows more accurate

Question 11

describe rod pathway

Answer 11

rod contacts only an ON bipolar cell which doesn’t contact RGCs. Uses amacrine cells to piggy back on SAME RGCs as rods

Question 12

how many types of ganglion cells are there

Answer 12

15-20

Question 13

ipRGCs. what do they contain? what do they do?

Answer 13

intrinsically photosensitive ganglion cells. contain melanopsin. Contribute to circadian (SCN) and pupil response (OPN). DON’T remove eye if not necessary!