Lecture 15: Vision Flashcards

1
Q

What neurotransmitter does photoreceptors secrete?

A

Glutamate

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2
Q

The amount of light reaching the retina is controlled by the what

A

IRIS

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3
Q

The Ciliary muscle helps to what

A

Control the shape of the Lens

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4
Q

What are the 4 layers of protection of the eye

A

Eyeball
Eyelid
Eyelashes
Tears

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5
Q

Describe the Iris

A

Controls amount of light that can enter by using 2 set of smooth muscles

Circular = constricts
Radical = Dilates
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6
Q

Describe the Pupil

A

opening where light enters

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7
Q

Describe the Lens

A

Focus light on the retina (Fovea

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8
Q

Describe the Sclera

A

Fluid filled spherical structure
Visible white layer of the eye
tough layer of connective tissue

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9
Q

Describe the Cornea

A

Fluid filled spherical structure
Anterior
Transparent layer that lets light rays through

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10
Q

Describe the Choroid

A

Fluid filled spherical structure
Contains blood vessels nourishing retina
Contains melanin under retina
Underneath Sclera

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11
Q

Describe the retina

A

Fluid filled spherical structure
Filled with Rods and cones
Axons of visual nerve fibers
Outer pigment cells

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12
Q

Describe the Posterior cavity

A

Fluid filled
Between lens and retina
Gelantinous viterious humor

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13
Q

Describe the anterior cavity

A

Fluid Filled
Between cornea and lens
Aqueous humor

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14
Q

What two things dilate or constrict the pupils

A

Circular/ radical muscles

Actions of the PNS/SNS

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15
Q

The Lens bends ____

A

Light rays

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16
Q

Accommodation in talking about vision relates to what

A

focusing

17
Q

When were looking at something from a distant describe the eye

A

Lens flat, weak
Ciliary muscles relaxed
Ligaments tight

18
Q

when were looking at something near, describe the eye

A

Lens rounded, strong
Ciliary muscles contracted (PNS stimulated)
Slack Ligaments

19
Q

What is the main neurotransmitter involved in accommodation and why

A

ACh

causes contraction of ciliary muscles and constriction of rings

20
Q

Describe Myopia and how its cured

A

Near-sightedness

Focal point falls before the retina

Corrected with concave lens )0

21
Q

Describe Hyperopia and how its cured

A

Far-sightedness

Focal point falls behind retina

Corrected with Convex lens (0

22
Q

Describe Presbyopia and how its cured

A

Aging

Ability to shape lens is lost

Corrected with bifocal (reading glasses)

23
Q

Describe Rods

A
More
Grayscale 
High sensitive
low acuity
Lots Converge on ganglion cells
Located in peripheral retina
24
Q

Describe cones

A
less
Colour vision
Lower sensitive
High acuity
Located in Fovea
25
Q

What do Ganglion cells do

A

process visual information that begins when light enters eye

26
Q

What do horizontal cells do

A

Help integrate and regulate input from photoreceptors and provide IPSP feedback to rods and cones

27
Q

what do Bipolar cells do

A

Located between photoreceptors and ganglion cells

Directly or indirectly transmit signals from photoreceptors to ganglion cells

28
Q

Describe Zonules

A

Fibrous strands connection ciliary body and lens

29
Q

Describe the Orbit

A

Eye socket

30
Q

Where is rhodopsin located

A

disk of rods and cones

31
Q

How is rhodopsin made

A

Opsin + Retinal

32
Q

What happens when it is dark

A

Rhodopsin inactive cGMP high

Cells depolarized constantly by Na+ and Ca+

33
Q

What happens when its light

A

Rhodopsin bleached by light activates it
Decrease in cGMP = CNG channels to close, hyperpolarizing the cell
Less transmitter released onto bipolar cells