Visual system

Question 1

the anterior chamber is filled with what?

Answer 1

aqueous humor

Question 2

the posterior chamber is filled with what?

Answer 2

vitreous humor

Question 3

what pulls on the suspensory ligaments to adjust the lens?

Answer 3

suspensory muscle

Question 4

dilation and constriction of the pupil

Answer 4

accommodation

Question 5

control of the pupil (light input) is controlled by what?

Answer 5

the sympathetic and parasympathetic systems and the radially arranged smooth muscles of the iris

Question 6

what happens in dim light?

Answer 6

radially arranged smooth muscle fibers contract (stimulated by sympathetic neurons) dilating the pupil

Question 7

what happens in bright light?

Answer 7

the circularly arranged smooth muscle fibers contract (stimulated by parasympathetic neurons) constricting the pupil

Question 8

because of the refraction of light, the image on the retina is ( )

Answer 8

reversed and upside down

Question 9

control of the lens

Answer 9

focus

Question 10

focus happens because of what?

Answer 10

the ciliary muscle changing the geometry of the lens (accommodation)

Question 11

to focus on distant objects, what happens?

Answer 11

the muscle relaxes, the suspensory ligaments go taught, and the lens flattens

Question 12

to focus on close objects, what happens?

Answer 12

muscle tightens and lens becomes thicker

Question 13

normal vision aka

Answer 13

emmetropia

Question 14

eye is too long

Answer 14

myopia (nearsightedness)

Question 15

eye is too short

Answer 15

hyperopia (farsightedness)

Question 16

when the refraction is uneven

Answer 16

astigmatism

Question 17

5 major cell types in the retina:

Answer 17

1) photoreceptors (rods and cones)
2) horizontal
3) bipolar
4) amacrine
5) ganglion

Question 18

what is the quickest route?

Answer 18

receptor to bipolar to ganglion cell

Question 19

what cells are largely involved in processing?

Answer 19

horizontal and amacrine

Question 20

because receptors are next to the pigmented epithelium, light must come through ( ) to stimulate photoreceptors

Answer 20

all of the other cell types including blood vessels

Question 21

both rods and cones contain what?

Answer 21

outer and inner segments

Question 22

rods or cones: more sensitive color blind

Answer 22

rods

Question 23

3 types of cones

Answer 23

1) blue
2) green
3) red

Question 24

cones are concentrated where?

Answer 24

fovea

Question 25

what about the fovea gives it better color and feature detection?

Answer 25

less convergence

Question 26

activation: photoreceptors release what type of NT?

Answer 26

inhibitory

Question 27

photoreceptors contain many ( ) channels

Answer 27

Na+

Question 28

the Na+ channels are open in the dark, known as ( )

Answer 28

dark current

Question 29

what inhibits the release of the photoceptor inhibitory neurotransmitters, thus activating the system

Answer 29

light

Question 30

light to impulse: what absorbs light?

Answer 30

a photopigment

Question 31

the visual G-proteins

Answer 31

transducins

Question 32

transducins bind to and activate an enzyme that converts ( )

Answer 32

cGMP to GMP

Question 33

cGMP leads to closure of Na+ channels, causing what?

Answer 33

hyperpolarization of the cell and less secretion of inhibitory NT, thus stimulating the neuron

Question 34

primary visual cortex

Answer 34

area 17

Question 35

ganglion cells do not respond to

Answer 35

diffuse light

Question 36

"visual field" of ganglion cells

Answer 36

on-center/off surround and off-center/on surround

Question 37

on-center cells (on-center/off surround)

Answer 37

spots of light surrounded by dark

Question 38

off-center cells (off center/on surround)

Answer 38

spots of dark surrounded by light

Question 39

gives us the ability to amplify contrasts

Answer 39

on/off center cells

Question 40

simple cells in cortex respond best to what?

Answer 40

bars of light or bars of dark in a particular space and of a particular orientation

Question 41

complex cells in cortex respond best to what?

Answer 41

lines of a specific orientation that move in a particular direction

Question 42

hypercomplex cells in cortex respond best to what?

Answer 42

bars of a specific length that have a particular bend or corner

Question 43

what are processed separately then merge?

Answer 43

motion and form

Question 44

5 important retinal cells

Answer 44

1) ganglion 2) amacrine 3) bipolar 4) horizontal 5) photoreceptors

Question 45

where are the receptors located?

Answer 45

next to the pigmented epithelium

Question 46

where does light come from?

Answer 46

?

Question 47

photoreceptors release

Answer 47

inhibitory NTs

Question 48

slide

Answer 48

12

Question 49

photoreceptors are open when?

Answer 49

in dark

Question 50

what inhibits the release of the photoreceptor inhibitory NTs?

Answer 50

light

Question 51

what absorbs light?

Answer 51

photopigment

Question 52

slide

Answer 52

14

Question 53

photopigment converts 11-cis-retinene to what?

Answer 53

all-trans-retinene

Question 54

what dissociates from the opsin?

Answer 54

all-trans-retinene

Question 55

what activate the enzyme that decreases cGMP?

Answer 55

tansducins (G Protein)