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Human Physiology Block 1 > Visual system > Flashcards

Visual system Flashcards

1
Q

the anterior chamber is filled with what?

A

aqueous humor

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2
Q

the posterior chamber is filled with what?

A

vitreous humor

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3
Q

what pulls on the suspensory ligaments to adjust the lens?

A

suspensory muscle

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4
Q

dilation and constriction of the pupil

A

accommodation

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5
Q

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

A

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

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6
Q

what happens in dim light?

A

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

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7
Q

what happens in bright light?

A

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

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8
Q

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

A

reversed and upside down

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9
Q

control of the lens

A

focus

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10
Q

focus happens because of what?

A

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

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11
Q

to focus on distant objects, what happens?

A

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

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12
Q

to focus on close objects, what happens?

A

muscle tightens and lens becomes thicker

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13
Q

normal vision aka

A

emmetropia

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14
Q

eye is too long

A

myopia (nearsightedness)

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15
Q

eye is too short

A

hyperopia (farsightedness)

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16
Q

when the refraction is uneven

A

astigmatism

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17
Q

5 major cell types in the retina:

A

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

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18
Q

what is the quickest route?

A

receptor to bipolar to ganglion cell

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19
Q

what cells are largely involved in processing?

A

horizontal and amacrine

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20
Q

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

A

all of the other cell types including blood vessels

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21
Q

both rods and cones contain what?

A

outer and inner segments

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22
Q

rods or cones: more sensitive color blind

A

rods

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23
Q

3 types of cones

A

1) blue
2) green
3) red

24
Q

cones are concentrated where?

A

fovea

25
Q

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

A

less convergence

26
Q

activation: photoreceptors release what type of NT?

A

inhibitory

27
Q

photoreceptors contain many ( ) channels

A

Na+

28
Q

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

A

dark current

29
Q

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

A

light

30
Q

light to impulse: what absorbs light?

A

a photopigment

31
Q

the visual G-proteins

A

transducins

32
Q

transducins bind to and activate an enzyme that converts ( )

A

cGMP to GMP

33
Q

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

A

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

34
Q

primary visual cortex

A

area 17

35
Q

ganglion cells do not respond to

A

diffuse light

36
Q

“visual field” of ganglion cells

A

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

37
Q

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

A

spots of light surrounded by dark

38
Q

off-center cells (off center/on surround)

A

spots of dark surrounded by light

39
Q

gives us the ability to amplify contrasts

A

on/off center cells

40
Q

simple cells in cortex respond best to what?

A

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

41
Q

complex cells in cortex respond best to what?

A

lines of a specific orientation that move in a particular direction

42
Q

hypercomplex cells in cortex respond best to what?

A

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

43
Q

what are processed separately then merge?

A

motion and form

44
Q

5 important retinal cells

A

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

45
Q

where are the receptors located?

A

next to the pigmented epithelium

46
Q

where does light come from?

A

?

47
Q

photoreceptors release

A

inhibitory NTs

48
Q

slide

A

12

49
Q

photoreceptors are open when?

A

in dark

50
Q

what inhibits the release of the photoreceptor inhibitory NTs?

A

light

51
Q

what absorbs light?

A

photopigment

52
Q

slide

A

14

53
Q

photopigment converts 11-cis-retinene to what?

A

all-trans-retinene

54
Q

what dissociates from the opsin?

A

all-trans-retinene

55
Q

what activate the enzyme that decreases cGMP?

A

tansducins (G Protein)

Human Physiology Block 1 (15 decks)

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