vision 1

Question 1

what is the visual pathway of light within the eye

Answer 1

light enters the cornea where most refraction occurs, it goes through the aqueous humor, pupil, lens, vitreous humour, then hits retina

Question 2

explain the pupiliary reflex

Answer 2

the retina projects to the pretectum, edinger westphal nucleus, ciliary ganglion, then innervates the ciliary muscle of the iris
-reflex in both eyes

Question 3

how does accomodation of the lens occur for near focus

Answer 3

the cilliary muscle is stimulated/contracts, the zonule fibers lessen tension, and the lens becomes rounder/thicker

Question 4

how does accomodation of the lens occur for far focus

Answer 4

the cilliary muscle does not contract, the zonule fibers have high tension, and the lens is flat

Question 5

myopia

Answer 5

when you cannot see far away, corrected with a concave lens

Question 6

hyperopia

Answer 6

cannot see near/hyperfocusing on far away objects, corrected with convex lens

Question 7

what part of the visual field do the left temporal retinal ganglion cells see

Answer 7

right nasal visual field

Question 8

what part of the visual field do the right nasal retinal ganglion cells see

Answer 8

the left temporal visual field

Question 9

what part of the total visual field can be seen by one eye

Answer 9

one eye can see 90 degrees of its ipsilateral visual field and 60 degrees of the contralateral visual field

Question 10

describe the laminar organization of the retinal ganglion cells

Answer 10

pigment epithelium, outer segment layer (contains photoreceptor cell bodies), outer plexiform layer (where horizontal cells synapse with photoreceptor cells and bipolar cells), inner nuclear layer(bipolar cell bodies), inner plexiform layer (where amacrine cells, bipolar cells, and ganglion cells synapse), ganglion cell layer, and nerve fiber layer

Question 11

what are the two main functions of the pigment epithelium layer

Answer 11

-the pigment epithelium plays a big role in phagocytosis of the discs in the photoreceptors
-it absorbs excess light

Question 12

scotopic

Answer 12

primarily rod cell vision, poor acuity,

Question 13

mesotopic

Answer 13

rod and cone cell vision, moonlight/starlight

Question 14

phototopic

Answer 14

rod saturation begins, mostly cone cell vision, high acuity
indoor lighting, sunlight

Question 15

what happens at the optic disk

Answer 15

ganglion cell axons exit the eye to the optic nerve, no photoreceptors, blind spot

Question 16

fovea

Answer 16

receives input when you intentionally focus on something, one to one cone cell and ganglion cell ratio gives you incredibly high acuity,

Question 17

do you understand how transducin and phosphodiesterase recover once we return to dark from light

Answer 17

if not, watch that part of the lecture again!

Question 18

wavelength of blue, green, and red cones

Answer 18

short, medium, long

Question 19

what two cones are both on the X chromosome

Answer 19

red and green, explains why red/green colorblindness is so common

Question 20

protanopia

Answer 20

no absorption of red

Question 21

deuteranopia

Answer 21

no absorption of green

Question 22

what mechanisms allow for dark adaptation to occur faster than light adaptation

Answer 22

IS THIS TRUEpupilliary reflex, R regeneration, and the outnumbering of rods to retinal ganglion cells

Question 23

how does calcium contribute to decreasing the sensitivity to light at greater luminances

Answer 23

-by decreasing inhibition of guanylate cyclase which hydrolyzes cGMP
-by decreasing inhibition of rhodopsin kinase which normally promotes arrestin
-affinity for cGMP receptors/driving force tapers off as more calcium comes into the cell

Question 24

describe stimulation of receptive fields and transduction in bipolar cells

Answer 24

receptive fields are stimulated by their centers and surrounds by light, send graded potentials

Question 25

rg9 bind to transducin alpha to stimulate gtpase activity, transducin alpha gtp dissociates from pde, transducin alpha gdp binds to transducin beta and gamma, pde now has inhibitory gamma subunit and is inhibited

Question 26

what does calcium inhibit

Answer 26

rhodopsin kinase and guanylate cyclase

Question 27

where does phototransduction take place

Answer 27

in the disc membranes/rods

Question 28

why do we need red and green cones

Answer 28

to provide information about color, and also visual high def image information, shapes, and edges(most of them)