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Block 5 Week 2 Meg > Von Bartheld: Vision 1 > Flashcards

Von Bartheld: Vision 1 Flashcards

1
Q

A convex lens is a converging lens, and has a (blank) focal point

A

positive

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2
Q

A concave lens is a diverging lens, and has a (blank) focal point

A

negative

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3
Q

What is the focal point?

A

the distance of the focal point (image formation) from the lens

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4
Q

What is the equation for a diopter?

A

1/focal length

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5
Q

A 10 diopter lens has a focal length of (blank)

A

10 cm

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6
Q

What is the equation for focal power?

A

refractive index/focal length

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7
Q

What structure is primarily responsible for refractive power?

A

anterior curvature of the cornea

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8
Q

What’s this:

Accommodation decreases with age

A

presbyopia

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9
Q

Nearsightedness

A

myopia

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10
Q

Farsightedness

A

hyperopia

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11
Q

In myopia, what kind of lens do you use?

A

concave

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12
Q

In hyperopia, what kind of lens do you use?

A

convex

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13
Q

What’s this:
Vision is blurred due to irregular curvature of the cornea or lens. The cornea may not be perfectly round, but may have a “football shape.”

A

astigmatism

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14
Q

What creates the blind spot?

A

the optic nerve

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15
Q

What are the 5 cell types in the retina?
Which cells are closest to the light?
Which cells are close to the pigment epithelium?

A 
ganglion cells *insert into optic nerve, closest to light
bipolar cells
amacrine cells
horizontal cells
rods/cones *close to pigment epithelium
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16
Q

Where are the rods primarily located?

Where are the cones primarily located?

A

most rods in the periphery, very few in the fovea

most cones in the fovea

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17
Q

Are there rods or cones in the area outside of the fovea?

A

there is a mix of both!

think of the rods decreasing as you get toward the fovea and the cones increasing abruptly as you get toward the fovea

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18
Q

The fovea is a (blank) zone with several (blank)

A

avascular; cones

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19
Q

Rods and cones have a close relationship with the (blank)

A

pigment epithelium

20
Q

What part of the rod cell is shed and renewed every couple of weeks or so?

A

photoreceptor disc

21
Q

Do rods or cones adapt more quickly to a light stimulus?

A

cones; rods are not as fast adapting

22
Q

How do rods differ from cones in terms of their convergence onto bipolar cells?

A

1 cone: 1 bipolar cell

several rods: 1 bipolar cell

23
Q

What happens to cone cells in response to light?

A

hyperpolarization

24
Q

Rods have Na+, K+, and Ca+ channels. How do these channels differ in light vs. dark?

A

In the dark, the channels are open and Na+ and Ca++ can flow in, while K+ flows out. This leads to depolarization. In the light, the channels close, leading to hyperpolarization.

25
Q

Rods are (blank) in the light, and (blank) in the dark

A

hyperpolarized; depolarized

26
Q

Na+/K+/Ca++ channels are (blank) in the light, and (blank) in the dark

A

closed; open

27
Q

derivative of Vit A

A

retinal

28
Q

What does a deficiency of Vit A lead to?

A

night blindness

29
Q

List the steps in the phototransduction second messenger cascade

A

light reaches rhodopsin (retinal) –> activates transducin –> activates phosphodiesterase –> releases cGMP –> channels close

30
Q

Light activating rhodopsin creates a (blank) signal amplification

A

HUGE
***1 rhodopsin can lead to the activation of 800 transducin molecules. Each transducin does 1 phosphodiesterase. Each phosphodiesterase does 6 GMP, so this is a rapid and huge signal amplification!!!

31
Q

When light reaches rhodopsin, it undergoes a configurational change from 11-cis retinol to (blank)

A

all-trans retinol

32
Q

What is the difference in the adaptation to dark between rods and cones?

A

rods take much longer to adjust to the dark than cones do

33
Q

How many different pigments are there for cones? How many for rods?

A

3 different pigments for cones; 1 for rods

34
Q

(blank) are involved in cone pigments and color vision

A

genetics

35
Q

What does perception of light intensity depend on?

A

the context/background

36
Q

Discuss on and off-center ganglion cells.

A

There are ganglion cells that fire an AP when they receive a stimulus in the center There are off-center ganglion cells that fire an AP when the stimulus in the surround.

37
Q

What do on-center and off-center ganglion cells help to enhance?

A

contrast

38
Q

On-center ganglion cells will only fire when the stimulus reaches the (blank)

A

center

39
Q

Why is it important to have a center vs. surround response?

A

this allows us to see things that are relevant

40
Q

What does the pupil do to increase depth of focus?

A

constrict

41
Q

What 3 methods are used by the visual system to perceive distance?

A
  1. relative object size
  2. moving parallax (move head side to side and objects that move more quickly are closer)
  3. stereopsis: info coming in to left eye is a bit different that info coming in to right eye
42
Q

Each eye receives a slightly different image of an object on its retina because each eye is ~2 inches apart.

A

stereopsis

43
Q

The difference between images received by the right and left eye is greater when an object is (blank) to your eyes. Images on the retina become more (blank) the farther they are from your eyes

A

close; similar

44
Q

Eye pathology seen in diabetic retinopathy

A

cotton wool spots
yellow exudates
microaneurysms (blots of blood)

45
Q

What nerve is bilateral papilledema likely to affect? What will this cause?

A

CN 6; inability to use lateral rectus on affected side (cannot fully abduct eye)

46
Q

What kind of imaging do you order to test for increased CSF pressure leading to papilledema?

A

MRI

Block 5 Week 2 Meg (10 decks)

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