Vision Flashcards

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1
Q

Refraction

A

Bending of light rays

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2
Q

Vision Process

A
  1. Light is focused through the lens
  2. The cornea bend light rays and focuses the image on the retina
  3. Focus is adjusted by changes in the shape of the lens
  4. Rods and Cones are activated, releasing NT molecules
  5. Triggers Bipolar Cells that connect with Ganglion Cells
  6. Axons form the optic nerve that carry information to the brain
  7. Either the Scotopic or Photopic System is activated
    - Scotopic (Rods): Rhodpsin is hit by light it triggers G protein transducin, causing sodium ion channels to close creating a hyperpolarization
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3
Q

Ciliary Muscles

A

Control the shape of the lens

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4
Q

Pupil

A

Controls the amount of light that enters the eye

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5
Q

Extraocular Muscles

A

Extend from the outside of the eyeball.

Fixating still or moving targets require control of these muscles

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6
Q

Bipolar Cells

A

Located in the retina and receive information from rods and cones and pass the information to retinal ganglion cells.

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7
Q

Ganglion Cells

A

A class of cells in the retina whose axons form the optic nerve

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8
Q

Horizontal Cells

A

Contact both the receptor cells and the bipolar cells

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9
Q

Amacrine Cells

A

Contact both the bipolar cells and the ganglion cells

Especially significant in inhibitory interactions within the retina

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10
Q

Rods, Cones, Bipolar Cells, and Horizontal Cells generate…

A

Local potentials

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11
Q

Ganglion Cells generate…

A

Action potentials

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12
Q

Scotopic System

A

Operates with rods and works in dim light

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13
Q

Photopic System

A

Operates at high levels of light, shows sensitivity to color and involves the cones

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14
Q

Rods

A

Work in dim light
Contain Rhodopsin
Concentrated in the periphery of the retina

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15
Q

Cones

A

Work to distinguish colors
Contain Opsin
Concentrated in the fovea

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16
Q

The size of the hyperpolarizing photoreceptor potential determines…

A

how much less synaptic transmitter will be released

17
Q

The process required to stimulate the visual receptors helps account for…

A

Sensitivity
Integration
Adaption

18
Q

Photoreceptor adaptation factors

A

Varying concentration of calcium ions

The recombination of retinal and opsin

19
Q

There are no photoreceptors in the..

A

Optic Disc

20
Q

Rods provide…

A

High sensitivity with limited acuity

21
Q

Cones provide…

A

High acuity with limited sensitivity

22
Q

Lateral Inhibition

A

Interconnected neurons inhibit their neighbors, producing contrast at the edges of regions

23
Q

Optic Chiasm

A

The point at which the two optic nerves meet

24
Q

Lateral Geniculate Nucleus

A

The part of the thalamus that receives information from the optic tract and sends it to visual areas in the occipital cortex

25
Q

Scotoma

A

Blindness

26
Q

On-Center Bipolar Cells

A

Turning a light on in the center of an on-center cell excites the cell because it receives less glutamate which otherwise inhibits on-center bipolar cells

27
Q

Off-Center Bipolar Cells

A

Turning off light in the center of an off-center bipolar cell’s receptive field excites the cell because it receives more glutamate which depolarizes off-center bipolar cells

28
Q

Bipolar cells also release…

A

Glutamate.

Therefore, when a light is turned on, on-center bipolar cells depolarize on-center ganglion cells and when a light is turned off, off-center bipolar cells depolarize (excite) off-center ganglion cells

29
Q

On-center/Off-surround

A

Referring to a concentric receptive field in which the center excites the cell of interest while the surround inhibits it

30
Q

Off-center/On-surround

A

Referring to a concentric receptive field in which the center inhibits the cell of interest while the surround excites it

31
Q

Parvocellular vs Magnocellular

A

Small vs. Big

32
Q

Hubel and Wiesel

A

Reported that visual cortical cells require more specific elongated stimuli than those that activate LGN cells.

33
Q

Simple Cortical Cells

A

A cell in the visual cortex that responds best to an edge or a bar that has a particular width, orientation and location

34
Q

Complex Cortical Cells

A

A cell in the visual cortex that responds best to a bar of a particular size and orientation anywhere within a particular area of the visual field

35
Q

Trichromatic Hypothesis

A

There are three different types of cones, each excited by a different region of the spectrum and each having a separate pathway to the brain

36
Q

Opponent-Process Hypothesis

A

The theory that color vision depends on systems that produce opposite responses to light of different wavelengths

37
Q

Hemoltz

A

Trichromatic Hypothesis

38
Q

Hering

A

Opponent-Process Hypothesis