Overview Of Visual Systems

Front 1

label

Back 1

anatomy of the eye

Front 2

Emmetropia (normal)

Back 2

Describe the vision acuity of this individual

Front 3

Myopia (nearsighted)

Back 3

Describe the vision of this individual

Front 4

Hyperopia (Farsightedness)

Back 4

Describe the vision of this individual

Front 5

Describe the pathway light takes as it moves through the layers of the eye

Back 5

Nerve fiber layer
Ganglion cell layer
Inner Plexiform Layer
Inner Nuclear Layer
Outer Plexiform Layer
Outer Nuclear Layer
Photoreceptors
Pigment Epithelium

Front 6

Label the different components of the diagram

Back 6

Components

Front 7

Label the portions of the visual pathway

Back 7

Answers

Front 8

Which reflex is this?
Label the parts

Back 8

The Pupillary Reflex

Front 9

Which reflex follows a
similar pathway to the
pupillary reflex?

Back 9

The accomodation /
convergence reflex

Front 10

Describe the shape
of an accommodated
lens.

Back 10

The lens increases in diameter and approaches a round shape.

Front 11

Fill in the blanks

Back 11

Answers

Front 12

Describe Macular Sparing and the theories behind it.

Back 12

Macular Sparing is due to a cortical lesion
Two theories:
1. Macula occupies a large amount of primary visual cortex: therefore in a cortical lesion it is likely that part will be spared.
1. Watershed region: dual blood supply allows sparing

Front 13

What are the 3 main layers of the eye?

Back 13

1. Sclera/Cornea
2. Uveal Tract (Choroid, ciliary body and iris)
3. Retina

Front 14

What are the 3 chambers of the eye? Which chamber is the largest?

Back 14

1. Anterior aqueous humor
2. Posterior aqueous humor
3. Vitreous humor
The vitreous humor is the largest

Front 15

Which layer of the eye is avascular?

Back 15

The cornea

Front 16

The sclera and the cornea are for the most part continuous. Where does each begin and end?

Back 16

The sclera surrounds the posterior 5/6ths of the eyeball. The cornea, then, surrounds 1/6th of the eyeball.

Front 17

Define the following components of the sclera:
1. Suprachoroidal Lamina
2. Tenon's space

Back 17

1. melanocytes in loose CT
2. detached region of the sclera at the sclera-cornea junction

Front 18

From outer to inner:
1. Epithelium - stratified squamous
2. Bowman's membrane
3. Stroma
4. Descemet's membrane
5. Endothelium - simple squamous

Back 18

What are the 5 layers of the cornea?

Front 19

The uveal tract is divided into 3 regions. What are they?

Back 19

1. Choroid
2. Ciliary Body
3. Iris

Front 20

What is the choroid made of and what is found in this material?

Back 20

A loose CT matrix that contains fibroblasts, melanocytes, lymphoid cells

Front 21

What is the layer of the choroid that nourishes the retina called?

Back 21

Choriocapillary layer

Front 22

What is the name of the membrane that acts as a barrier between the choroid and the retina?

Back 22

Bruch's membrane

Front 23

The ciliary body is actually a ________ that has extensions called _________.

Back 23

Ciliary muscle, ciliary processes

Front 24

What is the function of the ciliary processes?

Back 24

Anchors lens and aids in lens accommodation

Front 25

Accommodation is _________ focusing while the iris controls _______ focusing.

Back 25

fine, coarse

Front 26

What is the function of ciliary epithelium?

Back 26

secrete aqueous humor of anterior and posterior chamber

Front 27

The sympathetic nervous system innervates which pupillary muscle?

Back 27

dilator pupillae

Front 28

The parasympathetic nervous system innervates which pupillary muscle?

Back 28

sphincter pupillae

Front 29

Label the layers of the lens
Give a characteristic of each

Back 29

1. Lens Capsule - thick basal lamina
2. Subcapsular epithelium - "stem cell" (regenerating) cell layer of the lens
3. Lens fibers - filled with crystallin protien that refracts light

Front 30

What are the 3 layers of the retina?
What is found in each layer?

Back 30

From outer to inner:
1. outer layer - photoreceptor cells
2. middle layer - bipolar neurons
3. inner layer - ganglion neurons from optic nerve

Front 31

What is this a slide of?
Name the layers

Back 31

Retina
Answers

Front 32

Where are Muller cells found?
What is their function?

Back 32

The retina - they are specialized astrocytes that form the internal and external limiting membranes

Front 33

Name the non-nuclear layers of the Retina.

Back 33

Answers

Front 34

How many rods are in the average retina and where are they located within the retina?

Back 34

~120 million
more concentrated along the edges of the retina

Front 35

Which are extremely light sensitive: rods or cones?

Back 35

Rods - they see black & white and are used in night vision

Front 36

What is rhodopsin and where is it found?

Back 36

photopigment; found in disks of rod cells

Front 37

How many cones are in the average retina and where are they located within the retina?

Back 37

~6 million (less than rods)
more concentrated along back of retina and fovea

Front 38

Which are extremely color sensitive: rods or cones?

Back 38

cones

Front 39

What is an amacrine cell and where is it found?

Back 39

Various neurons in the retina: they synapse with different photoreceptors. function not understood

Front 40

What is a Limbus and where is it found?

Back 40

trabecular meshwork at corneoscleral junction; contains canal of Schlemm

Front 41

How does aqueous humor drain from the anterior chamber into the episcleral vasculature?

Back 41

Via the canal of Schlemm

Front 42

What are the components of the vitreous humor?

Back 42

H2O - 99%, collagen, hyaluronic acid molecules

Front 43

There are no ___________ at the blind spot. What is another name for the blind spot?

Back 43

photoreceptors
Optic papilla or optic disc is another name

Front 44

What are the glands of Moll and Zeis and where are they found?

Back 44

both found in eyelid
Moll - sweat gland
Zeis - sebaceous gland

Front 45

Which cells make synaptic contact in the outer plexiform layer of the retina?

Back 45

photoreceptors, bipolar and horizontal cells

Front 46

Which cells make synaptic contact in the inner plexiform layer of the retina?

Back 46

bipolar, amacrine, ganglion cells

Front 47

[cGMP] is ________ (high/low) in the photoreceptor cell in the dark.

Back 47

high (photoreceptors are activated at in the dark: cGMP keeps the ion channels open)

Front 48

Light closes cation channels to inactivate the photoreceptors. They are closed in a 3 step process - what is it?

Back 48

1. Light activates pigment molecules in disc membrane
2. activated pigment stimulates a G-protein. THis G-protein activates cGMP phosphodiesterase (which breaks down cGMP)
3. as cellular [cGMP] is lowered the channels close. This reduces the inward cation current and the cell hyperpolarizes.

Front 49

light coming from the right visual field is projected onto the ________ portion of the left retina and the _______ portion of the right retina.

Back 49

temporal
nasal

Front 50

The fovea is always ________ to the optic disc

Back 50

lateral

Front 51

Where does the fovea sit in the visual field?
Where does the blind spot sit in the visual field?

Back 51

In the center
slightly lateral to the fovea

Front 52

The Lateral Geniculate Nucleus (LGN) is found _______.

Back 52

in the posterior portion of the thalamus

Front 53

Where does the 1st synapse in the visual pathway occur?

Back 53

At the LGN

Front 54

Optic fibers associated with the fovea project onto the ________.

Back 54

posterior calcarine cortex

Front 55

Meyers loop contains ________ visual fields which project ____________.

Back 55

superior
on the inferior calcarine fissure.

Front 56

The _______________ portions of the visual field stay ipsilateral, whereas the ___________ portions of the visual field cross at the _________.

Back 56

Temporal
Nasal
Optic Chiasm

Front 57

Pupillary light reflex:

1. receptors?
2. afferent limb?
3. CNS center?
4. efferent limb?
5. peripheral effector?

Back 57

1. photoreceptors
2. CN II
3. pretectal area (tectal=midbrain)& Edinger-Westphal nuclei.
4. CN III
5. sphincter pupillae (bilaterally)

Front 58

Is there a decussation in the pupillary light reflex? If so, where is it?

Back 58

Yes. In the CNS (pretectal area and E-W nuclei)
Information decussates here b/c there is bilateral projection from the pretectal area to the E-W nuclei via the posterior commissure)

Front 59

The Accommodation reflex:
1. Receptors?
2. Afferent Limb?
3. CNS centers?
4. Efferent Limb?
5. Peripheral Effector?

Back 59

1. photoreceptors
2. CN II
3. Lateral Geniculate Body, primary visual cortex, E-W nuclei
4. CN III
5. sphincter pupillae muscle (pupillary constriction) and ciliary body muscle (lens accommodation)

Front 60

When the ciliary body muscles are contracted what happens to the lens? Why?

Back 60

The lens gets fatter. Tightening the ciliary body muscle releases tension on the suspensory ligaments of the lens: this allows the lens to fatten

Front 61

To see far away how is your lens shaped?
To see close up how is your lens shaped?

Back 61

far away --> stretched out and thin
close up --> fat

Front 62

What is an Argyll-Robertson pupil? What is it a sign of?

Back 62

pupils are:
small
don't react to light
DO constrict on accommodation
A sign of neurosyphilis

Front 63

What is Horner's syndrome?

Back 63

any damage to sympathetic pathways in either the brainstem, intermediolateral cell column or superior cervical ganglion.

Front 64

How does a lesion in descending sympathetics present?

Back 64

1. ptosis (drooping eyelid)
2. miosis (constricted, fixed pupil)
3. anhydrosis (no sweating on ipsilateral face)

Front 65

The sympathetic pathway has 3 synapses. Where are they?

Back 65

1. brainstem (hypothalamus)
2. intermediolateral cell column in an upper thoracic spinal cord segment
3. superior cervical ganglion

Front 66

The smooth muscle elevator of the eyelid is ___________ active.

Back 66

tonically

Front 67

What is the major function of the superior colliculus?

Back 67

Integration of visual, auditory and somatosensory information resulting in orientation to a particular stimulus. Can be via head, eye or neck movements.

Front 68

Where does the tectospinal pathway originate?

Back 68

the superior colliculus; it is a descending motor pathway

Front 69

If a visual field defect was only in one eye, where would the lesion be?

Back 69

In the optic nerve of the affected eye (before the optic chiasm)

Front 70

scotoma

Back 70

an area within the visual field where vision is absent or depressed. (artificial BLIND SPOT)

Front 71

anopia

Back 71

complete loss of vision in one or both eyes

Front 72

hemianopia

Back 72

loss of vision in one half of the visual field of one or both eyes

Front 73

homonymous hemianopia

Back 73

hemianopia restricted to one visual field (L or R)

Front 74

heteronymous hemianopia

Back 74

loss of vision in opposite halves of the visual field. (ie. bilateral temporal field is lost)

Front 75

quadrantanopia

Back 75

loss of vision in a quadrant of a visual field

Front 76

Meyer's loop carries information from which visual field?
Where does it project?

Back 76

Superior visual field
Projects to the inferior calcarine cortex

Front 77

Fibers from the inferior visual fields project where?

Back 77

Superior calcarine cortex

Front 78

Function of Tectospinal Pathway?

Back 78

Controls neurons that innervate proximal and axial musculature (common function - orient head to sensory stimulus)

Front 79

Blood supply to primary visual cortex?
Blood supply to macula's area on the primary visual cortex?

Back 79

PCA (Posterior Cerebral Artery)
Macula has both MCA and PCA

Front 80

What is iodopsin and where is it found?

Back 80

iodopsin is the photopigment used by cone photoreceptors.
3 different varieties