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NS Ch 1 > Ch 11 Vision: The Eye > Flashcards

Ch 11 Vision: The Eye Flashcards

1
Q

Eye is part of CNS of PNS?

A

CNS

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2
Q

Optic Nerve is made of what?

A

Ganglionic axons

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3
Q

Types of eye neurons?

A

Photoreceptor, bipolar cells, ganglion cells, amacrine cells, horizontal cells

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4
Q

Horizontal cells

A

luminance (contrast to varied light intensity), connects bipolar to photoreceptors

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5
Q

The higher the intensity of flashed light on a cone the more it?

A

Hyperpolarises until it hits saturation

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6
Q

Retinoid Cycle

A

Transforms all-trans retinal back to 11-cis retinal, allows for photon capture

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7
Q

When light hits photoreceptor and closes cGMP-gated Na+ channels, the regulatory effects of there being less Ca2+ inside the cell is?

A

Reduce sensitivity of the receptor to light. (e.g., increase guanylate cyclase cGMP & arrestin). Photoreceptors are most sensitive to light at low levels of illumination. As levels of illumination increase, sensitivity decreases, preventing receptors from saturating and thereby greatly extending the range of light intensities over which they operate!

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8
Q

Light Adaptation

A

The more light, the lower the sensitivity which extends the range of light intensities the receptors operate

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9
Q

Rods have what kind of sensitivity to light and spatial resolution/acuity?

A

high sensitivity to light, low resolution.acuity

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10
Q

Cones have what kind of sensitivity to light and spatial resolution/acuity?

A

relatively insensitive to light, high acuity

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11
Q

region in eye with best visual acuity

A

foveola

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12
Q

What are on-center off-center ganglion cells most responsive to?

A

Their receptive fields are most responsive to contrast in illuminance. Emphasizes regions where there is a difference in luminance.

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13
Q

Eye muscles/lens adjusts to near object how?

A

Cornea curves, ciliary muscle contracts, zonule fiber relaxes

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14
Q

Eye muscles/lens adjust to distant object?

A

Cornea flattens, zonule fiber contracts, ciliary muscle relaxes

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15
Q

When the ciliary muscles contract to see near objects allowing the elasticity of the lens to curve more, this is called?

A

Accommodation

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16
Q

Nearsighted. Cant see distant objects

A

Myopic. Eye ball too long, corneal surface too curved.

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17
Q

Farsighted. Cant see close objects.

A

Hyperopic. Eye ball too short. Refracting system too weak.

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18
Q

Presbyopia

A

Inability to accommodate. As you get old, lose accommodative ability of lens (ability to curve)

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19
Q

Corrective lens for myopia

A

Concave lens (diverging) minus

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20
Q

Corrective lens for hyperopia/presbyopia

A

Convex lens (converging) plus

21
Q

Anterior Chamber

A

Contains Anterior Humor. Nutrients for cornea and cell. Replenished 12 times a day.

22
Q

Sclera

A

Outermost layer of eye

23
Q

Choroid

A

Vasculature and melanin pigment

24
Q

Vitreous humor

A

the fluid in between the lens and retina

25
Q

Most refraction in eye done by?

A

Cornea

26
Q

Optic nerve is which crania nerve?

A

2nd Cranial Nerve

27
Q

Eyes take sensory information and convert energy from the electromagnetic spectrum to electrical signals (AP). This is called?

A

Transduction

28
Q

Image on retina is?

A

Upside down and backwards

29
Q

Having normal vision?

A

Emmetropia

30
Q

Astigmatism

A

Cornea or lens not symmetrical, light not bent evenly

31
Q

What are the Errors of Refraction?

A

Myopia, Hyperopia, Astigmatism

32
Q

At how many feet does the ciliary muscle relax?

A

20 ft or greater. Ciliary relaxes. Suspensory ligament/zonule fiber taut, lens taut/flattens/least convex

33
Q

lateral cell in inner layer?

A

amacrine cell

34
Q

lateral cell in outer layer?

A

horizontal. laterally integrates photoreceptors and bipolar cells to maintain vision’s sensitivity to contrast and expand range of intensities.

35
Q

Pigment Epithelium does what?

A

Shedding at out tips of photoreceptor to prevent blindness

36
Q

Describe phototransduction

A

Light hits rhodopsin (rod) induces conformational change in retinal from 11-cis to all-trans which activates transducin (alpha-gtp subunit) which activates PDE (phosphodiesterase) which hydrolyzes cGMP and closes cGMP-gated Na+ channels. Hyperpolarizes cell.
On-Center Bipolar cell’s mGlut (metabotropic) is which when bound to glutamate, has a hyperpolarizing effect (closes cGMP-gated Na+ channels)

37
Q

What affect does glutamate have on on-center bipolar/ganglionic cells?

A

Glutamate hyperpolarizes on-center cells. (dark)

No glutamate depolarizes on-center cell (light)

38
Q

Glutamate affect on off-center bipolar cell

A

Depolarizes bipolar cell like it does photoreceptor

39
Q

Bipolar ionotropic receptors?

A

AMPA & Kainate. Na and Ca. Excited by glutamate. (dark)

40
Q

Bipolar metabotropic receptor

A

G-coupled. mGluR6. Inhibited by glutamate. Light, photoreceptor hyperpolarizes and bipolar cell depolarizes as a result.

41
Q

Parasympathetic constriction of pupil uses what muscles?

A

Sphincter Circular muscles constrict

42
Q

Sympathetic dilation of pupil uses what muscle?

A

Radial contraction

43
Q

Eye movement: allows eye to jump, reading

A

Saccadic Movement

44
Q

Reflex responds to constriction of pupil in bright light

A

Pupillary reflex. Sphincter/Circular Muscle constrict.

45
Q

Area in brain coordinates eye movement

A

Superior colliculi

46
Q

Smooth movement that tracks moving image and keeps image on fovea

A

Smooth pursuit movement

47
Q

Photoreceptor bleaching is prevented by what kind of movement?

A

Fixational Movement

48
Q

Light shines on the Surround vs outside of the receptive field – what affect does each have?

A

When on the Surround, the cell response rate is lower than resting state, and when the light is outside of the receptive field it is at resting state. Inhibition when on Surround.

49
Q

Center-Surround relationship

A

Surround antagonizes the response to stimulation of receptive field

NS Ch 1 (4 decks)

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