Vision

Question 1

What 3 things are part of the uveal tract?

Answer 1

1) choroid
2) ciliary body
3) iris

Question 2

The ______ is part of the sclera.

Answer 2

cornea

Question 3

The retina contains ______

Answer 3

neurons

Question 4

Describe the choroid.

Answer 4

largest, capillary, pigment epithelium

Question 5

The ciliary body has both muscular & vascular components that go around what?

Answer 5

the lens

Question 6

How do the iris muscles work?

Answer 6

muscles with opposing functions for pupil size

Question 7

the anterior and posterior chambers of the eye are for what?

Answer 7

rate of production/drainage (glaucoma)

Question 8

the vitreous humor deals with what?

Answer 8

shape & housekeeping functions (floaters

Question 9

Normal vision requires that the optical media of the eye be ________

Answer 9

transparent

Question 10

Where do you generate a focused image?

Answer 10

on the surface of the retina

Question 11

What contributes to most of the necessary refraction when generating a focused image?

Answer 11

the cornea

Question 12

What has more refraction power, the lens or cornea?

Answer 12

cornea

Question 13

What contributes to the clarity of images on the retina?

Answer 13

adjustments in the size of the pupil

Question 14

When looking at something far away, what muscles are relaxed?

Answer 14

ciliary muscle (and tension in zonule fibers, which flattens the lens)

Question 15

What is a blind spot called?

Answer 15

scotoma

Question 16

where is the optic disk located?

Answer 16

it is an area within the retinal surface

Question 17

what does the optic disk measure?

Answer 17

intercranial pressure

Question 18

What does macula lutea do?

Answer 18

It is the part of the retina that is responsible for sharp, detailed central vision

Question 19

What do horizontal cells enable?

Answer 19

lateral interactions between photoreceptors and bipolar cells

Question 20

What do horizontal cells maintain?

Answer 20

the visual system’s sensitivity to contrast, over a wide range of light intensities (luminance)

Question 21

What are different subclasses of amacrine cells thought to do?

Answer 21

make distinct contributions to visual function (modulation of the visual info)

Question 22

What is the house of the photoreceptors?

Answer 22

the pigment epithelium

Question 23

what is pigment epithelium involved in?

Answer 23

1) the shedding –> phagocytosis of the outer clump of disks
2) regeneration of the photopigment

Question 24

What happens in terms of APs during phototransduciton?

Answer 24

photoreceptors do not exhibit APs

Question 25

What does the light activation in phototransduction cause?

Answer 25

a graded change in membrane potential

Question 26

What happens when light is introduced to a rod?

Answer 26

the Na+ influx is reduced (Na cannot go through the channel into the cell)

Question 27

Are the rods hyperpolarized or depolarized when it is dark?

Answer 27

depolarized

Question 28

Are the rods hyperpolarized or depolarized when it is light?

Answer 28

hyperpolarization

Question 29

When there is light, the retinals change from _____ to _____

Answer 29

cis to trans

Question 30

What does IRBP mean?

Answer 30

inter photoreceptor retinoid binding protein

Question 31

The magnitude of the phototransduction amplification varies with the prevailing level of what?

Answer 31

illumination

Question 32

When are photoreceptors most sensitive to light?

Answer 32

at lower levels of illumination

Question 33

As levels of illumination increase, sensitivity _____, preventing the receptors from saturating.

Answer 33

decreases

Question 34

Light-induced closure of the Ca2+ cannels leads to what?

Answer 34

a net decrease in the internal Ca2+ concentration that triggers a number of changes in the phototransduction cascade (which will reduce the sensitivity of the receptor to light)

Question 35

What is the ratio of cone connections?

Answer 35

1:1

Question 36

What is the ratio of rod connections?

Answer 36

1 rod bipolar cell : 15-30 rods

Question 37

Why are rods more sensitive than cones?

Answer 37

1 rod activates several other rods

Question 38

What is the cone system specialized for?

Answer 38

acuity at the expense of sensivity

Question 39

The rod system has very low ____ _____ but is extremely sensitive to light.

Answer 39

spatial resolution

Question 40

In the scotopic visual function, what is activated?

Answer 40

only rods

Question 41

In the mesopic visual function, what is activated?

Answer 41

only cones

Question 42

In the photopic visual function, what is activated?

Answer 42

both cones and rods

Question 43

Rods are mainly used in _____ environments.

Answer 43

dark

Question 44

Cones are only used in ______ environments.

Answer 44

bright

Question 45

What is tritanopia?

Answer 45

blue/yellow color blindness

Question 46

How many photopigments do rods contain?

Answer 46

1

Question 47

How many photopigments do cones contain?

Answer 47

3

Question 48

What are the 3 types of cones?

Answer 48

1) blue (short) 2) green (medium) 3) red (long)

Question 49

Each ganglionic cell responds to the stimulation of what?

Answer 49

a cell's receptive field

Question 50

what is a cell's receptive field?

Answer 50

a small circular patch of the retina

Question 51

What are the two classes of ganglion cells?

Answer 51

ON-center and OFF-center

Question 52

What do ON-center cells increase?

Answer 52

increase the discharge rate to luminance increments in the receptive field center

Question 53

What do OFF-center cells increase?

Answer 53

increase their discharge rate to luminance decrements in the receptive field center

Question 54

The selective response of ON- and OFF-center bipolar cells to light increments and decrements is explained by the fact that they express what?

Answer 54

different types of glutamate receptors

Question 55

Increases in background level of illumination are accompanied by ____________ such that greater stimulus intensities are required to achieve the same discharge rate (amacrine cells)

Answer 55

adaptive shifts in the ganglion cell’s operating range

Question 56

What are ganglion cells sensitive to?

Answer 56

differences between the level of illumination that falls on the receptive field center and the level of illumination that falls on the surround

Question 57

Response of an ______-center ganglion cell to the increase in the size of a spot of light placed in the receptive field center

Answer 57

ON

Question 58

As the spot increases in size to fill the center, the response of the ganglion cell ________. As it extends into the receptive field surround, the response of the ganglion cell _________.

Answer 58

increases ; decreases

Question 59

Because of their antagonistic surrounds, most ganglion cells respond how?

Answer 59

much more vigorously to small spots of light confined to their receptive field centers

Question 60

what does hypothalamus regulate?

Answer 60

regulation of circadian rhythms

Question 61

What is the function of pretectum?

Answer 61

reflex control of pupil and lens

Question 62

what is the function of the superior colliculus?

Answer 62

orienting the movements of head and eyes

Question 63

What is the pupillary light reflex?

Answer 63

a bilateral projection from the retina to the pretctum

Question 64

What contains the preganglionic parasympathetic neurons that send their axons via the oculomotor nerve to terminate in which neurons in the ciliary ganglion which innervate the constrictor muscle in the iris.

Answer 64

the edinger-westphal nucleus

Question 65

What provides an important diagnostic tool that allows the physician to test the integrity of the visual sensory apparatus, the motor outflow to the pupillary muscles, and the central pathways that mediate the reflex.

Answer 65

the pupillary reflex

Question 66

Lateral visual field will go to the _____ retina

Answer 66

nasal

Question 67

Temporal retina will associate with the ______ visual field.

Answer 67

right

Question 68

Where is the upper visual field represented?

Answer 68

below the calcarine sulcus

Question 69

The lower visual field is represented where?

Answer 69

above the calcarine

Question 70

Where is the fovea represented?

Answer 70

in the posterior part of the striate cortex

Question 71

More peripheral regions of the retina are represented progressively more ______ parts of the striate cortex.

Answer 71

anterior

Question 72

What do neurons in the ________ ______ ______ respond selectively to oriented edges.

Answer 72

primary visual cortex

Question 73

What do neurons in the primary visual cortex typically respond vigorously to?

Answer 73

a bar of light oriented at a particular angle (and less strongly to other orientations)

Question 74

Retinohypothalamic tract is part of what?

Answer 74

circadian system

Question 75

Photic information to the suprachiasmatic nucleus (SCN) is transmitted from the retina via the _____________.

Answer 75

retinohypothalamic tract (RHT)