Special Senses II

Question 1

What is the role of the lens?

Answer 1

Accomodation

Question 2

What flattens the lens?

Answer 2

Suspensory ligaments (ciliary muscle relaxes)

Question 3

Lens flattening = near or far vision?

Answer 3

Far

Question 4

Ciliary muscle contraction does what to the lens? What is the for?

Answer 4

Lens assume a more spherical shape

–near vision

Question 5

The ciliary muscle of the eye contracts in response to what type of stimulation?

Answer 5

Parasympathetic

Question 6

What is presbyopia?

Answer 6

Near point of vision recedes

Question 7

True or false: the optic tract is part of the PNS, and is myelinated by schwann cells

Answer 7

False– part of the CNS, myelinated by oligodendrocytes

Question 8

Round lens = contracted or not ciliary muscle?

Answer 8

Contracted

Question 9

What are the three processes that occur while looking at a near object?

Answer 9

• Accommodation
• Convergence of visual axes
• Pupils constrict

Question 10

What are the cells in the RPE that spread out horizontally?

Answer 10

Horizontal cells

Amacrine cells

Question 11

What is a scotoma?

Answer 11

Visual field defect

Question 12

Where are the rods and cones in the RPE?

Answer 12

In the back

Question 13

What are the cells the the rod/cones connects to?

Answer 13

Bipolar cell, then

Ganglion cell

Question 14

Do we regenerate rods?

Answer 14

No, but we renew them

Question 15

What are the cells that are involved in scotopic vision (rods or cones)?

Answer 15

Rods

Question 16

What are the cells that are involved in phototopic vision (rods or cones)?

Answer 16

Cones

Question 17

What is the function of Vit A?

Answer 17

Part of the rod pigment rhodopsin

Question 18

What is the only cell in the retina, beside rods and cones, that can sense light? What pigment do these cells contain? Purpose?

Answer 18

intrinsically photosensitive retinal ganglion cells contain melanopsin; seem to measure overall light intensity

Question 19

What is the MOA of retinal detachment?

Answer 19

Vitreous seeps behind the retina, causing suffocation of the RPE.

Question 20

Does the optic disk have photoreceptors? How about the fovea?

Answer 20

Fovea= yes, duh

Optic disk = no

Question 21

Why is the foveola an avascular zone?

Answer 21

You can’t see through blood vessels

Question 22

Where is the maximum number of rods?

Answer 22

Parafoveally

Question 23

What is meant by the term meso topic?

Answer 23

Using both rods and cones

Question 24

How many types of pigments are there in cones?

Answer 24

3

Question 25

What is the symptom of Vit A deficiency?

Answer 25

Night blindness

Question 26

What happens in the dark to rods and cones?

Answer 26

Na and Ca channels are held open by cGMP, to depolarize by constantly leaking K

Question 27

What happens in the light to rods and cones? (3)

Answer 27

- Na+ / Ca++ channels close - photoreceptor hyperpolarizes as K+ leaves cell - decrease in release of neurotransmitters

Question 28

Photoreceptors hyperpolarize or depolarize to light?

Answer 28

Hyper polarize

Question 29

What is the molecular change that occurs with rod bleaching? How does it get back?

Answer 29

11-cis retinal goes to all trans retinal Chaperones bring it back to cis

Question 30

Why is the eye affected in MS?

Answer 30

Oligodendrocytes; not schwann cells

Question 31

The retina is form by evagination of what part of the embryological brain?

Answer 31

Diencephalon

Question 32

The axons of what cells make up the optic nerve and tract?

Answer 32

Ganglion cells

Question 33

Do rods, bipolar cells, or ganglion cells have action potentials?

Answer 33

Only ganglion cells

Question 34

What happens to neurotransmitter release from rods as they are exposed to light?

Answer 34

Less is released

Question 35

Why do off-center ganglion cells fire less than on-center ones?

Answer 35

To give better contrast

Question 36

Where does processing of light information first occur?

Answer 36

In the retina (contrast bit)

Question 37

Why do you not need action potentials in the retina?

Answer 37

Distances are so short

Question 38

Processing of information makes use of what type of potentials -

Answer 38

Graded (receptor and synaptic)

Question 39

What is the neurotransmitter released by photoreceptors?

Answer 39

Glutamate

Question 40

What is a receptive field in the visual system?

Answer 40

the area of retina from which the neuron can be influenced.

Question 41

What are the places that the optic tract ends up in?

Answer 41

Hypothalamus LGN Superior colliculus

Question 42

What is the nucleus involved in the pupillary light reflex? What are the CNs involved?

Answer 42

CN II--EWN(x2)--CN III

Question 43

Review the pathways of CN II as per neuroanatomy, if you do not recall them!

Answer 43

LGN

Question 44

The top part of the visual field is processed in which part of the occipital cortex?

Answer 44

Inferior

Question 45

The lower part of the visual field is processed in which part of the occipital cortex?

Answer 45

Superior

Question 46

Where are Meyer's loop found?

Answer 46

From LGN, sweeps through the temporal lobe, to the calcarine suclus

Question 47

Look at slide 38 and make some notecards offa that.

Answer 47

Should be review anyways

Question 48

Lesion of Meyer's loop = ?

Answer 48

superior – quadrant anopsia contralateral to lesion of | Meyer’s loop

Question 49

Inflammation of the optic disk can produce what type of opia?

Answer 49

Central Scotoma

Question 50

What parts of the eye register movement vs visual acuity and color perception?

Answer 50

Different ganglion cells

Question 51

What are the two main visual pathways from the striate cortex to higher order visual areas?

Answer 51

Dorsal stream | Ventral stream

Question 52

What is the function of the dorsal stream?

Answer 52

analysis of motion and relative positions of objects in visual scene

Question 53

What is the function of the ventral stream?

Answer 53

high-level form vision and object recognition

Question 54

What is the part of the brain that links all the hemi fields together?

Answer 54

Corpus callosum

Question 55

What is prosopagnosia?

Answer 55

Inability to identify faces

Question 56

What is cerebral akinetopsia?

Answer 56

Inability to see motion

Question 57

Which cone type sense short wavelengths (red, green, or blue)?

Answer 57

Blue

Question 58

Which cone type sense middle wavelengths (red, green, or blue)?

Answer 58

Green

Question 59

Which cone type sense long wavelengths (red, green, or blue)?

Answer 59

Red

Question 60

True or false: you can differentiate colors based on input from a single cone

Answer 60

False--

Question 61

What causes red-green color blindness?

Answer 61

Loss of either red or green cones

Question 62

What happens if you are missing both red and green cones?

Answer 62

Color blindness

Question 63

What is Monochromatopsia?

Answer 63

have either one cone or no cones.

Question 64

What are the charts that test for color blindness?

Answer 64

Ishihara charts

Question 65

Genes for the red and green cones pigments are on what chromosome?

Answer 65

X

Question 66

What chromosome is the blue cone on?

Answer 66

7

Question 67

Rhodopsin gene is on which chromosome?

Answer 67

3

Question 68

What are the monocular depth cues?

Answer 68

How big the image on the retina is

Question 69

What is sensory fusion?

Answer 69

fixate both eyes on one point so that left and right images fall on corresponding positions in the two retinas

Question 70

What causes strabismus?

Answer 70

Failure of the eyes to fixate on the same point

Question 71

What is amblyopia?

Answer 71

Suppression of vision from the strabismus eye causing loss of vision