Phototransduction and Eye disorders Lec 16

Question 1

Emmetropic

Answer 1

Normal eye

Question 2

Accommodation

Answer 2

contract ciliary muscles
thickening lens
shorten focal length

Question 3

Myopia

Answer 3

Nearsighted
cornea too curved or eyeball too long
concave lens

Question 4

Hyperopia

Answer 4

Farsighted
cornea not curved enough or eyeball too short
Convex lens

Question 5

Positive lens

Answer 5

Convex

move focal point forward

Question 6

Negative lens

Answer 6

Concave

Move focal point backward

Question 7

Presbyopia

Answer 7

Natural loss of ability to accommodate

Question 8

Glaucoma

Answer 8

Damage optic nerve
loss of peripheral vision
Elevated intraocular pressure

Question 9

Retina vertical info flow

Answer 9

Photoreceptors- bipolar cells- ganglion cells

NT glutamate

Question 10

Retina lateral info flow

Answer 10

Mediated by horizontal cells and amacrine cells

NT GABA or Glycine

Question 11

In darkness

Answer 11

NT released continually

Combined action of Na, Ca and K- keep depolarized at -40mv

Question 12

In light

Answer 12

Graded hyperpol
spreads passively to reduce glutamate release
Reduction of cGMP in outer segment
Reduce Ca and Na inflow
K ions still flow out

Question 13

Pigment activation

Answer 13

11-cis to all-trans