Physiology

Question 1

Types of photoreceptors

Answer 1

rods and cones

Question 2

how many types of cones are there

Answer 2

3

Question 3

function of photoreceptors

Answer 3

convert electromagnetic radiation into electrical signals

Question 4

photoreceptors have an already hyper/depolarised resting membrane potential

Answer 4

depolarised

Question 5

light exposure causes hyper/depolarisation in photoreceptors
and how?

Answer 5

HYPERpolarisation
light closes the cGMP Na+ channel by reducing cGMP concentration meaning less is available to bind to the Na channel causing it to shut

Question 6

hyperpolarisation from light exposure causes an increase/decrease in glutamate release

Answer 6

decrease

Question 7

Dark current is produced from open/closed cGMP Na+ channel

Answer 7

open

Question 8

what happens when the cGMP Na+ channel is closed

Answer 8

there is less Na influx resulting in hyperpolarisation

Question 9

in the dark, Na channels are open/closed leading to more/less glutamate production

Answer 9

open

more

Question 10

in response to light, Na channels are open/closed leading to more/less glutamate production

Answer 10

closed

less

Question 11

what is visual acuity determined by

Answer 11

photoreceptor spacing and refractive power

Question 12

rods let you see in normal/dim light

Answer 12

dim

Question 13

rods have high convergence, what does this mean

Answer 13

more rod cells to 1 ganglion

Question 14

what effect does a high convergence have on light sensitivity and acuity

Answer 14

higher convergence –> greater sensitivity, lower acuity

Question 15

cones let you see in dim/normal light

Answer 15

normal daylight

Question 16

cones have a high/low convergence

what does this mean

Answer 16

low
fewer cone cells to 1 ganglion
better acuity, less sensitivity

Question 17

what is the fovea

Answer 17

found on centre of macula in the retina that has the greatest concentration of cones

Question 18

Rods are:
a/chromatic 
peripheral/central retina 
high/low convergence
high/low light sensitivity
high/low visual acuity

Answer 18

achromatic 
peripheral retina 
high convergence 
high light sensitivity 
low visual acuity

Question 19

Cones are:
a/chromatic 
peripheral/central retina 
high/low convergence
high/low light sensitivity
high/low visual acuity

Answer 19

chromatic
central retina 
low convergence
low light sensitivity 
high visual acuity

Question 20

the right visual field is processed by the left/right side of the brain

Answer 20

left

Question 21

superior visual field is processed by the upper/lower cortex

Answer 21

lower