Eyes (triple only) Flashcards

1
Q

Name the process used to focus light from near and far objects

A

Accommodation

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2
Q

What stimuli are the receptors of the eye sensitive to?

A

Light intensity

Colour

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3
Q

What are the 2 main functions of structures found within the eye?

A

Accommodation

Adaptation to dim light

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4
Q

Describe the structure and function of the retina

A

Found at the back of the eye
Contain light sensitive cells (rods and cones)
Light sensitive cells send impulses to the brain

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5
Q

Describe the structure and function of the optic nerve

A

Optic nerve connects the eye and the brain
Contains sensory neurones
Send electrical impulses from the retina to the brain

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6
Q

Describe the structure and function of the sclera

A

Tough outer layer of the eye

Protects internal structures

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7
Q

Describe the structure and function of the cornea

A

Curved transparent layer at the front of the eye
Lets light into the eye
Allows light to be focussed on the retina

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8
Q

Describe the structure and function of the iris

A

Iris is a muscle
Controls the size of the pupil by contracting and relaxing the muscles
Allows the eye to adjust to bright and dim light

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9
Q

Describe the structure and function of the ciliary muscles and suspensory ligaments

A

Hold the lens in place

Can change the shape of the lens

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10
Q

Describe how the iris alters the size of the pupil in bright light

A

Circular muscle contract
Radial muscles relax
makes pupil smaller to avoid damage to retina

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11
Q

Describe how the iris alters the size of the pupil in dim light

A

Circular muscles relax
Radial muscles contract
Makes pupil larger so more light can enter the eye

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12
Q

How does the eye focus on a close object?

A
Ciliary muscle contract
Suspensory ligaments loosen
Lens becomes thicker and more curved
Light is refracted strongly
Image forms on the retina
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13
Q

How does the eye focus on distant objects?

A
Ciliary muscles relax
Suspensory ligaments tighten
Lens is puller thinner 
Light is refracted less strongly
Image falls on the retina
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14
Q

What is myopia?

A

Short-sightedness
Lens becomes too curved
Light is focused in front of the retina
Images appear blurry

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15
Q

How can myopia be treated?

A

Using glasses or contact lenses
Concave lens
Spreads the light so they can be focused on the retina

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16
Q

What is hyperopia?

A

Long-sightedness
Lens is too flat
Light is focused behind the retina
Images appear blurry

17
Q

How can hyperopia be treated?

A

Using glasses or contact lenses
Convex lens
Brings light rays together
Image formed on the retina

18
Q

What is laser eye surgery?

A

Use lasers to fix visual defects n adults
Myopia - laser reduces the thickened of the cornea so light is refracted less strongly
Hyperopia - laser alters curvature of the cornea so light is refracted correctly

19
Q

How can replacement lenses by used to treat visual defects?

A

Replacement lens replaces the natural lens

20
Q

What are the risks of lens replacement?

A

Can cause retinal damage, cataracts and infections