B3.1.3 - The Eye Flashcards

1
Q

What is the eye?

A

The sense organ that allows you to see

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2
Q

Name the main structures of the eye.

A

Cornea, pupil, iris, lens, ciliary body, suspensory ligaments and optic nerve

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3
Q

Describe the cornea and its function.

A

A transparent coating on the front of the eye which protects the eye and refracts light entering the eye

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4
Q

Describe the iris and its function.

A

A coloured ring of muscle tissue which alters pupil size by contracting or relaxing

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5
Q

Describe the pupil and its function.

A

A central hole in the iris which allows light to enter the eye.

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6
Q

Describe the lens and its function.

A

Transparent biconcave lens which focus light clearly onto the retina.

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7
Q

Describe the ciliary body and its function.

A

A ring of muscle tissue which alters the shape of the lens

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8
Q

Describe the suspensory ligaments and its functions.

A

Ligament tissue which connects the ciliary muscle to the lens

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9
Q

Describe the optic nerve and its function

A

Nervous tissue which carries nerve impulses to the brain

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10
Q

How are images formed on the retina?

A

The cornea refracts incoming light rays which provides most of the focus to the incoming light, which passes through the pupil and is then further refracted by the lens, creating a sharp image on the retina.

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11
Q

What is meant by the term ‘refracts’?

A

Changes the direction of

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12
Q

What happens after a sharp image is on the retina?

A

Photoreceptors produce a nervous impulse due to the exposure of light which travels down the optic nerve to the brain, which interprets the impulses as a visual image.

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13
Q

What are photoreceptors

A

Light sensitive cells in the retina

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14
Q

What happens to the lens when your ciliary muscle contracts?

A

It becomes more convex (can focus on nearby objects)

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15
Q

What happens to the lens when your ciliary muscle relaxes?

A

It becomes less convex (can focus on distant objects)

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16
Q

What is short sightedness caused by?

A

A persons lens being too strong or by the eyeball being too long

17
Q

What is long sightedness caused by?

A

A persons lens being too weak or eyeball being too short

18
Q

What can be prescribed to correct long / short sightedness?

A

Glasses or contact lenses

19
Q

How do glasses / contact lenses affect vision?

A

Corrected short sight - Concave Ken’s bends the light rays outwards before they enter the eye

Correct long sights - Concave lens bends the light rays inwards before they enter the eye

20
Q

What do you call someone who has difficulty making out different colours?

A

Colour blind

21
Q

What are the two types of photoreceptor cells that a retina has?

A

Rods and Cones

22
Q

Describe the rods of photoreceptors.

A

Respond to light and allow you to see in low light conditions

23
Q

Describe the cones of photoreceptors.

A

Respond to different colours. There are different cone cells that respond to red, blue and green light

24
Q

What is the most common form of colour blindness?

A

Red - green

25
Q

How do you get colour blindness?

A

Genetically inherited