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Flashcards in Special Senses II Deck (71):
1

What is the role of the lens?

Accomodation

2

What flattens the lens?

Suspensory ligaments (ciliary muscle relaxes)

3

Lens flattening = near or far vision?

Far

4

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

Lens assume a more spherical shape

--near vision

5

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

Parasympathetic

6

What is presbyopia?

Near point of vision recedes

7

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

False-- part of the CNS, myelinated by oligodendrocytes

8

Round lens = contracted or not ciliary muscle?

Contracted

9

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

•Accommodation
•Convergence of visual axes
•Pupils constrict

10

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

Horizontal cells
Amacrine cells

11

What is a scotoma?

Visual field defect

12

Where are the rods and cones in the RPE?

In the back

13

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

Bipolar cell, then
Ganglion cell

14

Do we regenerate rods?

No, but we renew them

15

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

Rods

16

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

Cones

17

What is the function of Vit A?

Part of the rod pigment rhodopsin

18

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

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

19

What is the MOA of retinal detachment?

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

20

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

Fovea= yes, duh
Optic disk = no

21

Why is the foveola an avascular zone?

You can't see through blood vessels

22

Where is the maximum number of rods?

Parafoveally

23

What is meant by the term meso topic?

Using both rods and cones

24

How many types of pigments are there in cones?

3

25

What is the symptom of Vit A deficiency?

Night blindness

26

What happens in the dark to rods and cones?

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

27

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

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

28

Photoreceptors hyperpolarize or depolarize to light?

Hyper polarize

29

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

11-cis retinal goes to all trans retinal

Chaperones bring it back to cis

30

Why is the eye affected in MS?

Oligodendrocytes; not schwann cells

31

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

Diencephalon

32

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

Ganglion cells

33

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

Only ganglion cells

34

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

Less is released

35

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

To give better contrast

36

Where does processing of light information first occur?

In the retina (contrast bit)

37

Why do you not need action potentials in the retina?

Distances are so short

38

Processing of information makes use of what type of potentials -

Graded (receptor and synaptic)

39

What is the neurotransmitter released by photoreceptors?

Glutamate

40

What is a receptive field in the visual system?

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

41

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

Hypothalamus
LGN
Superior colliculus

42

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

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

43

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

LGN

44

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

Inferior

45

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

Superior

46

Where are Meyer's loop found?

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

47

Look at slide 38 and make some notecards offa that.

Should be review anyways

48

Lesion of Meyer's loop = ?

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

49

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

Central Scotoma

50

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

Different ganglion cells

51

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

Dorsal stream
Ventral stream

52

What is the function of the dorsal stream?

analysis of motion and relative positions of objects in visual scene

53

What is the function of the ventral stream?

high-level form vision and object recognition

54

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

Corpus callosum

55

What is prosopagnosia?

Inability to identify faces

56

What is cerebral akinetopsia?

Inability to see motion

57

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

Blue

58

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

Green

59

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

Red

60

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

False--

61

What causes red-green color blindness?

Loss of either red or green cones

62

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

Color blindness

63

What is Monochromatopsia?

have either one cone or no cones.

64

What are the charts that test for color blindness?

Ishihara charts

65

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

X

66

What chromosome is the blue cone on?

7

67

Rhodopsin gene is on which chromosome?

3

68

What are the monocular depth cues?

How big the image on the retina is

69

What is sensory fusion?

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

70

What causes strabismus?

Failure of the eyes to fixate on the same point

71

What is amblyopia?

Suppression of vision from the strabismus eye causing loss of vision