Chapter 10 Pt. 2 (Part 5)

Question 1

what are the two types of bipolar cells?

Answer 1

ON and OFF

Question 2

what are the two types of glutamate receptors?

Answer 2

ionotropic or metabotropic

Question 3

what does depolarization of a bipolar cell trigger?

Answer 3

graded potential which releases glutamate from the bipolar cell onto the retinal ganglion cell

Question 4

what triggers a graded potential which releases glutamate from the bipolar cell onto the retinal ganglion cell?

Answer 4

depolarization of a bipolar cell

Question 5

what are the only cells of the visual system that can fire an action potential?

Answer 5

ganglion cells

Question 6

how do we interpret things as different colors and shapes?

Answer 6

different combinations of action potentials coming through the optic nerve

Question 7

ionotropic cation channel =

Answer 7

OFF bipolar cell

Question 8

G protein-coupled receptor =

Answer 8

ON bipolar cell

Question 9

OFF bipolar cell =

Answer 9

ionotropic cation channel

Question 10

ON bipolar cell =

Answer 10

G protein-coupled receptor

Question 11

what do ionotropic glutamate receptors (fast ligand-gated ion channels) do when glutamate binds?

Answer 11

ALWAYS DEPOLARIZE

Question 12

what happens when a-subunit binds to multivalent Na+/Ca+2 channels?

Answer 12

closes the channel to cause metabotropic bipolar cell to hyperpolarize and stop releasing glutamate onto the RGC

Question 13

what do metabotropic glutamate receptors (G protein) do when glutamate binds?

Answer 13

ALWAYS HYPERPOLARIZE!

Question 14

what happens to a metabotropic receptor on the bipolar cell in the dark

Answer 14

photoreceptor releases glutamate onto it

Question 15

why are OFF bipolar cells called OFF?

Answer 15

they are depolarized when the light is off in the center

Question 16

why are ON bipolar cells called ON?

Answer 16

because they depolarize when the light is on in the center

Question 17

what happens if light strikes the center field but not the surround?

Answer 17

AP frequency is even less.

center is inhibited by both light and GABA so glutamate release is about 0

Question 18

when is AP frequency highest for OFF bipolar cells?

Answer 18

when light is OFF in the center and ON in the surround

Question 19

when does AP frequency decrease for OFF bipolar cells?

Answer 19

when light hits the entire RF and decreases even more when ON in the center and OFF in the surround

Question 20

will ON hyperpolarize or depolarize when glutamate binds?

Answer 20

hyperpolarize

Question 21

what happens to a hyperpolarized bipolar cell?

Answer 21

it will not stimulate RGC to fire an AP

Question 22

when is AP frequency lowest in ON bipolar cells?

Answer 22

light is off in the center and on in the surround

increases when light strikes the entire receptive field

Question 23

when is AP frequency the highest in ON bipolar cells?

Answer 23

light is ON in the center and OFF in the surround

Question 24

why can’t you see immediately when you go from light to dark?

Answer 24

rhodopsin in all of the disks in rods will be photo bleached

not enough light to activate any of the cones

Question 25

how would we perceive orange?

Answer 25

more red than green

Question 26

what forms the optic chiasm?

Answer 26

2 optic nerves meet at the brain stem

Question 27

which ganglia cross over?

Answer 27

1 L 1 R on each side of the brain