Lecture 22: vision 1

Question 1

which love is linked to vision?

Answer 1

occipital

Question 2

where is the retina located?

Answer 2

back of the eye

Question 3

is the retina light sensitive?

Answer 3

yes

Question 4

where to nerve fibres form the retina leave the eye?

Answer 4

love the eye in the optic nerve and synapse in the lateral geniculate nucleus

Question 5

after leaving the retina where do nerve fibres go?

Answer 5

the visual cortex

Question 6

what does vision depend on?

Answer 6

light sensitive cells in the retina at the rear of the eye

Question 7

what focuses light onto the retina?

Answer 7

cornea and lens

Question 8

what is the fovea?

Answer 8

region where
upper retinal
layers are thinned

Question 9

whats the order fo the front centre structure of the eye?

Answer 9

cornia
anterior chamber
iris
lens

Question 10

what is the structure of the retina?

Answer 10

photoreceptors
Outer plexiform layer
Horizontal cell
Bipolar cell
Amacrine cell
Inner plexiform layer
Ganglion cell

Question 11

how do photoreceptors increase there surface area?

Answer 11

They have an outer segment with stacks of membrane

Question 12

what do pigment molecules do?

Answer 12

collect light

Question 13

How many rods and cones do humans have?

Answer 13

120 mil rods

6 mil cones

Question 14

do nocturnal animals have more or less rods than humans?

Answer 14

more

Question 15

what do rods do and where are they located?

Answer 15

Rods are more sensitive
to light and occur in the
periphery

Question 16

what do cones do and where are they located?

Answer 16

Cones respond to different
wavelengths and are found
mainly in the fovea

Question 17

is the structure of the fovea whats above rods?

Answer 17

cones

Question 18

what happens to Vertebrate photoreceptors when stimulated ?

Answer 18

they become hyperpolarised
when stimulated, unlike
most receptors that
become depolarised

Question 19

How many types of rods are there?

Answer 19

1

Question 20

How many types of cones are there?

Answer 20

3

Question 21

what colour absorbance is associated with rods?

Answer 21

blue/green

Question 22

what colour absorbance is associated with cones?

Answer 22

red
green
blue

Question 23

How many cones can synapse with one bipolar?

Answer 23

one or a few

Question 24

what do cones have that is small?

Answer 24

small receptive fields for high-acuity colour vision in fovea

Question 25

How many rods synapse with one bipolar?

Answer 25

several

Question 26

rods subserve ___ ____ _______

Answer 26

low light vision

Question 27

what do photoreceptors synapse with?

Answer 27

bipolar cells

Question 28

what do bipolar produce and what they modulated by?

Answer 28

Bipolars produce graded receptor potentials modulated by horizontal cells

Question 29

A combination of inputs from photoreceptors and horizontal cells produces what?

Answer 29

two kinds of receptive field in bipolars, on centre and off centre

Question 30

If spot of light applied to centre of bipolar cells what happens?

Answer 30

on centre cel - excited, large response form ganglion cells

off centre cell - inhibitory, bipolar cell off, ganglion cell inhibited

Question 31

If a ring of light is applied to bipolar cells what happens?

Answer 31

on centre cell - Bipolar cell inhibited, response from ganglion cell shut down
off centre cell -Bipolar cell excited, ganglion cell responds

Question 32

what do ganglion cells have and what do they produce?

Answer 32

Ganglion cells also have on-centre and off-centre fields but produce action potentials

Question 33

where do the axons of ganglion go to?

Answer 33

Their axons go into the optic nerve to the LGN

Question 34

what do ganglion cell fibres enter?

Answer 34

fibres enter the optic nerve and chiasm

Question 35

what do fibres from the nasal retina do?

Answer 35

cross over (contralateral)

Question 36

what happens to fibres from the temporal retina?

Answer 36

remain ipsilateral