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S.N Physiology 2 > 8.4 Vision > Flashcards

8.4 Vision Flashcards

1
Q

What produces the aqueous humor?

A

cilliary processes

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2
Q

Functions of aqueous humor?

A
  • provides nutrients for the lens and cornea
  • creates refractive power of the eye
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3
Q

Vascular part of the eye includes

A

Choroid

ciliary body

iris

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4
Q

What gives the majority of refractive power of the eye

A
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5
Q

What controlls the ciliary muscles?

A

Parasympathetic NS

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6
Q

Describe the müller cells

A

Long glial cells

maintain extracellular environment by regulating K+ levels

NT uptake

glycogen storage

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7
Q

Who is more sensitive to light and why

A

Rods

bcs. In cones only a few synaps on a bipolar cell

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8
Q

Difference in activation of rods and cones?

A

rods have more Rhodopsin so less photons are needed for the activation of it (only one photn is needed)

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9
Q

What does Rhodopsin contain

A

Opsin and Retinal

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10
Q

Draw a diagram of photoreception

A
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11
Q

Define what is near point

A

the point nearest the eye at which an object is accurately focused on the retina when the maximum degree of accommodation is employed

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12
Q

How does the eyeball look like im hyperopia?

A

short eyeball

corrected by convex lens

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13
Q

How does the eyeball look like im myopia?

A

Long eye

fixed with concave lenses

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14
Q

What is the pressure inside the eyeball?

A

22 mmHg (Bernandlevi)

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15
Q

Describe the flow of the aqueous humor

A
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16
Q

What is the major refractive element of the eye?

A

Cornea (43 diopter)

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17
Q

What holds the lens in place?

A
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18
Q

Describe the layers of the retina

A
19
Q

The eye can dist. 2 aspects of light

______

______

A
20
Q

What are cones responsible for?

A

Best in day light, color vision

21
Q

Main visual pathway in thalamus is ______

A

LGB

22
Q

Lens equation

A
23
Q

Focal power of resting and accommodation (what cahnges?)

A
24
Q

What is astigmatisms?

A

Unequal focal power on different directions

25
Q

What is the intraocular pressure?

A

15mmHg

26
Q

What happens in glaucoma?

A

Intraocular pressur increases -> optic nerve damage -> vision loss

27
Q

Distribution of rods and cons in the retina

A
28
Q

Three types pf vision

A

Scotopic (only rods)

mesopic (both)

photopic (only cones)

29
Q

What is Rhodopsin?

A

Visual pigment

GPCR for light

Rhodopsib = opsin (7TM protein) + 11-cis retinal

30
Q

What happens in vit A deff?

A

Night blindness

31
Q

Phototransduction of rods in light

A

Light ► Rhodopsin (changes to metarhodopsin II) ►

Gt activation (transducin) ► at acrivstes cGMP Phosphodiesterase (PDE) ► cGMP decreases ►

CNG (Cyclic Nucleotide Gated) channels close (Na, Ca influx decreases) ► hyperpolarization ► Glu release decreases

32
Q

Describe the dark current of photoreceptors

A

CGMP is always produced and not broken down so CNG channels are open and influx of Na and Ca happens ► depol ► Glu release

33
Q

What does light evokes in photoreceptors?

A
34
Q

Define Critical Flicker Fusion Frequency

A

the frequency at which a flickering light is perceived as continuous

35
Q

When does Rhodopsin form?

A
36
Q

Two things can happen when hypopolarization of the photoreceptor membrane

A
37
Q

There are two types of receptors on _____ and _____cells

  1. _____
  2. _____
A

There are two types of receptors on bipolar and horizontal cells

  1. Ionotropic
  2. Metabotropic
38
Q

ionotropic receptors, which are depolarizing (excitatory), and metabo- tropic receptors, which are hyperpolarizing (inhibitory)

A

ionotropic receptors, which are depolarizing (excitatory), and metabo- tropic receptors, which are hyperpolarizing (inhibitory)

39
Q

Draw the optic pathway

A
40
Q

Why are horizontal cells important?

A
41
Q

Explain of herman grid illusion

A
42
Q

3 types of cones:

A

1) blue S (short)
2) green M (medium)
3) red L (large)

by wavelength

43
Q

3 layers of the eye

A
  1. outer fibrous (sclera, cornea)

2.

S.N Physiology 2 (9 decks)

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