B3.1.3 The Eye Flashcards

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1
Q

Describe cornea and it’s function

A

Transparent coating on the front of the eye
Protects eye by refracting light entering

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2
Q

Describe pupil and its function

A

Central hole in the iris
Allows light to enter the eye

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3
Q

Describe iris and it’s function

A

Coloured ring of muscle tissue
Alters pupil size by contracting or relaxing

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4
Q

Describe lens and it’s function

A

Transparent biconvex lens
Focuses light clearly onto the retina

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5
Q

Describe ciliary body and it’s function

A

Ring of muscle tissue
Alters shape of lens

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6
Q

Describe suspenseful ligaments and their function

A

Ligament tissue
Connects the ciliary muscle to the lens

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7
Q

Describe optic nerve and it’s function

A

Nervous tissue
Carries nerve impulses to the brain

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8
Q

Describe how images are formed

A

Cornea refracts incoming light rays
Providing most of the focus to incoming light
The light then passes through the pupil and is further refracted by lens
Creates a sharp image on the retina
Photoreceptors in retina produce nervous impulse when exposed to light
Impulse travels down optic nerve to brain which interprets impulses as a visual image

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9
Q

When ciliary muscle contracts…

A

Lens becomes more convex (fatter)
You can focus on nearby objects

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10
Q

When ciliary muscles relax

A

Lens becomes less convex (thinner)
You can focus on distant objects

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11
Q

What causes short sightedness?

A

A persons lens being too strong or the eyeball too big

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12
Q

What causes long sightedness

A

A persons lens too weak or eyeball too short

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13
Q

Concave lenses

A

Correct short sightedness
Bend light rays outwards before entering eye

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14
Q

Convex lenses

A

Correct long sightedness
Bend light rays inward before entering the eye

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15
Q

Two types of photoreceptor cells in retina

A

Rods- respond to light, allow you to see in low light levels
Cones- respond to different colours. Diff cone cells respond to red blue and green light

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16
Q

Explain the changes in the eye that occur as you look from a book to the front of a classroom.

A

Iris contracts so pupil is smaller to reduce the amount of light entering is eye, as the classroom environment typically has brighter
The ciliary muscles surrounding the lens contract, causing the lens to become more convex, enabling clear focus on the front of classroom