Nsp Week 2: Visual Systems (Blair)

Front 1

Which structure of the eye is the major refractive component?

Back 1

Cornea

Front 2

Which structure of the eye fine-tunes refraction for focusing light on retina (accomodation)

Back 2

Lens

Front 3

Which structure controls thickness of the lens during accomodation?

Back 3

Ciliary muscle

Front 4

Which structures connect lens to the ciliary muscle?

Back 4

Zonular fibers

Front 5

With contraction of the ciliary muscle, is the tension in zonular fibers high or low?

Back 5

Low

Front 6

Between which two layers of the eye is the choroid located?

Back 6

Between retina and sclera

Front 7

Which fluid is located in the anterior chamber and which is in the posterior chamber of the eye?

Back 7

Anterior chamber --> aqueous humor
Posterior chamber --> vitreous humor

Front 8

What is the region of greatest visual acuity?

Back 8

Fovea centralis

Front 9

Where is the "blind spot"?

Back 9

Optic disc
(entrance of the optic nerve)

Front 10

Aqueous humor is produced by which structure?

Back 10

Ciliary body

Front 11

How does the aqueous humor exit the anterior chamber?

Back 11

By passing through the "angle," into the trabecular meshwork, and then into the canal of Schlemm

Front 12

What causes glaucoma?

Back 12

Excessive build up of the aqueous humor, resulting in increased intraocular pressure.
Increased pressure is reflected back to the origin of the optic nerve and damages the nerve, producing blindness

Front 13

What is the most common type of glaucoma?

Back 13

Open angle

Front 14

What causes open angle glaucoma?

Back 14

The aqueous humor has access to the angle, but drainage through the canal of Schlemm is reduced

Front 15

Which type of glaucoma is a medical emergency?

Back 15

Closed-angle
(Pressure buildup occurs quickly and blindness can happen within 3 days)

Front 16

How does closed angle glaucoma develop?

Back 16

Flow of aqueous humor to anterior chamber is blocked, and pressure builds up behind the iris, forcing the iris to occlude the angle

Front 17

All drug treatments used for open angle glaucoma have one of two primary mechanism. What are they?

Back 17

1. Increasing outflow of aqueous humor
2. Reducing secretion

Front 18

List 5 classes of drugs used to treat open angle glaucoma

Back 18

1. Beta blockers
2. Prostaglandins
3. Cholinomimetics
4. Alpha agonists
5. Diuretics

Front 19

List 3 beta-blockers used to treat open-angle glaucoma

What is the MOA?
How are they administered?

Back 19

1. Timolol
2. Betaxolol
3. Careolol

*Decrease secretion of aqueous humor

*Eye drops

Front 20

List 2 prostaglandins used to treat open angle glaucoma

Back 20

1. Latanoprost
2. Bimatoprost

Front 21

What is the MOA of prostaglandins used to treat open angle glaucoma?
How are these drugs administered?

Back 21

Increase outflow of aqueous humor
*Eye drops

Front 22

List some side effects of prostaglandin eye drops

Back 22

1. Stinging/ burning of eye
2. Dry eyes
3. Redness of eyelids
4. Allergic reactions
5. Iris may darken or turn brown

Front 23

List 4 cholinomimetics used to treat open angle glaucoma. Which of these are indirect cholinomimetics?

Back 23

1. Pilocarpine
2. Carbachol
3. Physostigmine
4. Echothiophate

*Physostigmine and echothiphate are indirect cholinomimetics b/c they block acetylcholinesterase

Front 24

What is the MOA of cholinomimetics used to treat open angle glaucoma?

Back 24

increase outflow of aqueous humor

Front 25

List 2 side effects of cholinomimentics used for open angle glaucoma

Back 25

1. Miosis
2. Cyclospasm

Front 26

List 3 alpha agonists used to treat open angle glaucoma. What is the MOA of these?

Back 26

1. Epinephrine --> decrease synthesis of aqueous humor
2. Apraclonidine --> reduce secretion, increase outflow
3. Brimonidin --> reduce secretion, increase outflow

Front 27

What are the primary side effects of epinephrine?

Back 27

1. Mydriasis
2. Stinging of the eyes

Front 28

What are the side effects of Apraclonidine and brimonidine?

Back 28

1. Eye discomfort
2. Pounding heart beats
3. Shallow breathing

Front 29

List 2 diuretics used for the treatment of open angle glaucoma.
How are these administered?

Back 29

1. Acetazolamide --> orally
2. Dorzolamide --> eye drops

Front 30

What are the side effects of acetazolamide and dorzolamide used for open angle glaucoma?

Back 30

No significant side effects

Front 31

What is the MOA of the diuretics used to treat open angle glaucoma?

Back 31

Reduce secretion due to lack of HCO3-.

Front 32

Which combination drug is used to treat open angle gluacoma?

Back 32

Combination of dorzolamide and timolol

Front 33

What are the most common drugs currently administered for open angle glaucoma?

Back 33

Beta blockers and prostaglandins

Front 34

Which two classes of drugs are the only ones that can be used to treat closed angle glaucoma?

Back 34

1. Cholinomimetics
2. Acetazolamide

Front 35

Why should epinephrine NOT be used to treat closed angle glaucoma?

Back 35

The mydriatic effect enhances angle closure

Front 36

Visible light appears in wavelengths of what length?

Back 36

400 nm to 700 nm

Front 37

At which two interfaces in the eye does refraction occur?
Where does the greatest refraction occur?

Back 37

1. Cornea (greatest refraction)
2. Lens

Front 38

How does refraction change the orientation of an image?

Back 38

Image will be turned upside down and reversed from right to left on the retina

Front 39

Does an object that is closer or farther away require more refraction?
How does the ciliary muscle perform this take?

Back 39

Closer objects require more refraction

The ciliary muscle contracts, reducing the tension on the zonular fibers, allowing the lens to assume a more spherical shape, which increases its refractive ability

Front 40

If light rays focus on the retina, then the eyes are said to be ________.

Back 40

Emmetropic

Front 41

Far-sightedness is called..?

Back 41

Hyperopia

Front 42

Near-sightedness is called..?

Back 42

Myopia

Front 43

With hyperopia, is the eyeball too short or too long? How does this affect a person's ability to see objects up close and far away?

Back 43

Too short

Close objects appear blurry because image is focused BEHIND the retina
Far objects are clear because image can focus on the retina

Front 44

With myopia, is the eyeball too short or too long? How does this affect a person's ability to see objects up close and far away?

Back 44

Too long

Close objects are clear because they can be focused onto the retina
Far away objects are blurry because they are focused IN FRONT of the retina

Front 45

With age, the lens becomes stiffer, which prevents it from being able to assume a more round configuration. What is this condition called?

Back 45

Presbyopia

Front 46

What causes astigmatism?

Back 46

Uneven curvature of the cornea
Results in focusing an object at two separate places on the retina, producing blurry vision

Front 47

What type of lens do you use to correct hyperopia?

Back 47

Convex

Front 48

What type of lens do you use to correct myopia?

Back 48

Concave

Front 49

What type of lens is used to correct astigmatism?

Back 49

Cylindrical

Front 50

How much of the visual arc can each eye see?

Back 50

150 degrees

Front 51

How much of the visual field can be seen by both eyes? What is this portion called?
What are the most temporal regions called?

Back 51

120 degrees.
"Binocular zone"

"Monocular zones" are located temporally, are are the areas only seen by one eye

Front 52

List the layers of the retina from inside to outside

Back 52

1. Nerve fiber
2. Ganglion cell
3. Inner plexiform
4. Inner nuclear
5. Outer plexiform
6. Outer nuclear
7. Photoreceptor outer segments
8. Pigmented epithelium

Front 53

Nuclei of photoreceptor cells reside in which layer of the retina?

Back 53

Outer nuclear

Front 54

Cell bodies of bipolar, horizontal, and amacrine neurons reside in which layer of the retina?

Back 54

Inner nuclear layer

Front 55

The site of removal of old photoreceptor discs is within which layer of the retina?

Back 55

Pigmented epithelium

Front 56

Describe the distribution of rods and cones within the retina

Back 56

At the central region of the fovea (foveola), the fraction of cones is the greatest. Moving away from the fovea, the fraction of cones decreases and the fraction of rods increases

Front 57

Why is visual acuity highest in the fovea?

Back 57

In areas containing only cones, a single photoreceptor sends input to a single ganglion cell.
In areas mostly containing rods, about 40 photoreceptors ultimately converge on one ganglion cell

Front 58

Which photoreceptor cells are very sensitive to low levels of light/

Back 58

Rods

Front 59

All photopigments consist of which 2 molecules?

Back 59

1. Retinal (derivative of Vit A)
2. Opsin (protein)

Front 60

Where are photopigment molecules contained within the photoreceptors?

Back 60

In the disc membrane

Front 61

Which portion of the photoreceptor contains a light-sensing apparatus?

Back 61

Outer segment

Front 62

Absorption of light by the photopigment has what sort of effect?

Back 62

Absorption of light causes the cell to hyperpolarize, resulting in reduced release of neurotransmitter from the photoreceptor cell

Front 63

At which wavelengths do blue, green, and red cones absorb light at?

Back 63

Blue --> 420 nm
Green --> 531 nm
Red cones --> 558 nm

Front 64

Why are rods more sensitive to light than cones?

Back 64

There are more discs in rods, so there are more photopigments

Front 65

Which cells are the final output from the retina?

Back 65

Ganglion cells

Front 66

Axons of which cells converge at the optic disk to form the optic nerve?

Back 66

Ganglion cells

Front 67

Which cells are the only retinal cells that produce action potentials?

Back 67

Ganglion cells

(All the other cells use graded potentials)

Front 68

Describe the cell-to-cell transmission of visual input to the occipital cortex

Back 68

Photoreceptor --> bipolar cell --> ganglion cell --> (retinogeniculate projection)--> lateral geniculate neuron --> (optic radiation) --> visual cortex

Front 69

What is another term for the optic radiation?

Back 69

Geniculocalcarine pathway

Front 70

Describe when photoreceptors are depolarized/hyperpolarized based on light

Back 70

light --> hyperpolarized
dark --> depolarized

Front 71

What are the 2 types of bipolar cells?

Back 71

1. ON bipolar cells
2. OFF bipolar cells

Front 72

In the dark, do photoreceptors cells increase or decrease glutamate release? What is the effect on ON bipolar cells?

Back 72

Dark --> photoreceptors are depolarized and INCREASE glutamate release --> HYPERPOLARIZES ON bipolar cells

Front 73

When a photon strikes a photoreceptor, is the cell depolarized or hyperpolarized?
How does this affect ON bipolar cells?

Back 73

Photoreceptors are HYPERPOLARIZED.
This decreases the release of glutamate (which is normally inhibitory), resulting in DEPOLARIZATION of ON bipolar cells

Front 74

Which bipolar cells release more transmitter in the dark-- ON or OFF bipolar cells?

Back 74

OFF bipolar cells

Front 75

What is the effect of glutamate on OFF bipolar cells? Is glutamate release higher in the dark or light?

Back 75

Glutamate --> DEPOLARIZES OFF bipolar cells
This occurs in the dark, when glutamate release is highest

Front 76

The synaptic organization of which cells produce lateral inhibition?

Which inhibitory neurotransmitter is released by these cells?

Back 76

Horizontal cells
(receive input from photoreceptors, and then form synapses with other photoreceptors)

*Release GABA

Front 77

Ganglion cells receive synaptic input from which 2 cells?

Back 77

1. Bipolar cells
2. Amacrine cells

Front 78

When do ganglion cells fire most accurately?

Back 78

When the luminance contrast is the highest

Front 79

What are the 3 types of functional ganglion cells?

Back 79

1. M-type (magnocellular; large)
2. P-type (parvocellular; small)
3. K-type (koniocellular)

Front 80

Which type of ganglion cells are important for detecting motion?

Back 80

M-type (magnocellular)
They have large receptive fields

Front 81

Do M-type ganglion cells receive most of their input from rods or cones?

Back 81

Rods

Front 82

Do P-type ganglion cells receive most of their input from rods or cones?

Back 82

Cones

Front 83

Which ganglion cells are important for determining shape and color?

Back 83

P-type (parvocellular)
Small receptive fields, high visual acuity

Front 84

Which type of ganglion cells are primarily located near the fovea?

Back 84

P-type (parvocellular)

Front 85

Which type of ganglion cells are located throughout the retina?

Back 85

K-type (koniocellular)

Front 86

Most ganglion cells are of which type?

Back 86

P-type (parvocellular)

Front 87

List 3 functions of K-type ganglion cells

Back 87

1. Mediate pupillary light reflex
2. Participate in circadian rhythms
3. Detect color

Front 88

Which ganglion cells detect color, and which colors are sensed?

Back 88

P-cells --> red and green
K-cells --> blue and yellow

Front 89

Describe how the retina is divided into 4 quadrants

Back 89

1. "nasal hemiretina"
2. "temporal hemiretina"
3. "superior hemiretina"
4. "inferior hemiretina"

Front 90

List the general pathway for vision from retina to primary visual cortex

Back 90

Retina/ganglion cells --> optic nerve --> optic chiasm --> optic tract --> lateral geniculate nucleus --> primary visual cortex

Front 91

The left visual field is transmitted in which optic tract?

Back 91

Right optic tract
(info from left nasal retina and right temporal retina)

Front 92

A pituitary tumor can cause what type of visual deficit?

Back 92

Bitemporal hemianopsia
(damage to optic chiasm)

Front 93

Where does the optic tract terminate?

Back 93

Lateral geniculate nucleus

Front 94

Lesions in the optic tract produce what type of visual deficit?

Back 94

Homonymous hemianopsia

Front 95

Within which layers do nasal hemiretina (contralateral) fibers terminate in the lateral geniculate nucleus?

Back 95

Layers 1, 4, and 6

Front 96

Within which layers do temporal hemiretina (ipsilateral) fibers terminate in the lateral geniculate nucles?

Back 96

Layers 2, 3, and 5

Front 97

Which layers of the LGN receive axons from M ganglion cells?

Back 97

Layers 1 and 2

Front 98

Which layers of the LGN receive axons from P ganglion cells?

Back 98

Layers 3 - 6

Front 99

Where would a lesion be located if it resulted in a "pie on the floor" defect in vision?
What is this condition called?

Back 99

Quadrantinopsia
*Lesion in the parietal lobe may produce a visual defect in the contralateral inferior visual field

Front 100

An appropriately placed lesion in the temporal lobe that damages Meyer's loop will produce a quadrantinopsia in what part of the visual field?

Back 100

Contralateral superior visual field
"pie in the sky"

Front 101

The primary visual cortex is Brodmann's area...?

Back 101

17

Front 102

The primary visual cortex is marked by a prominent line which can be seen with the unaided eye. What is the name of this line?

Back 102

"Stripe of Gennari"

Front 103

The lingual gyrus receives info which portion of the visual field?

Back 103

Upper contralateral field

Front 104

The cuneus gyrus receives info from which portion of the visual field?

Back 104

Lower contralateral field

Front 105

The anterior portion of V1 represents which portion of the visual field?

Back 105

Peripheral portion

Front 106

A group of cortical neurons that receives input from P or K ganglion cells is thought to be mainly involved in determining the _______ of objects

Back 106

Color

Remember:
M --> motion
P --> shape
P/K --> color

Front 107

What are the two pathways from the primary visual cortex and what are their functions?

Back 107

1. Dorsal pathway --> "where" pathway; detects the location of objects in space, and is involved with detection of motion of objects
2. Ventral pathway --> "what" pathway; identification of objects

Front 108

Bilateral lesions in the dorsal pathway from the primary visual cortex will make it impossible to perceive what?

Back 108

Moving objects

Front 109

Which artery supplies the retina?

Back 109

Central retinal artery
(branch of the ophthalmic A)

Front 110

Which artery supplies the optic nerve?

Back 110

Ophthalmic artery

Front 111

Which artery supplies the optic chiasm?

Back 111

Anterior communicating

Front 112

Which artery supplies the optic tract?

Back 112

Anterior choroidal

Front 113

Which artery supplies the lateral geniculate nucleus?

Back 113

Thalamogeniculate

Front 114

Which artery supplies the optic radiations?

Back 114

Temporal portion --> Middle cerebral A
Parietal portion --> Posterior cerebral A

Front 115

Which artery supplies the primaryvisual cortex?

Back 115

Calcarine A