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Topic 2- Cells & Control 📄 > The Eye > Flashcards

The Eye Flashcards

1
Q

What is at the back of the eye?

A

The retina

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2
Q

What is the retina?

A

This layer contains light sensitive cells that can detect light and send impulses to the brain resulting in the formation of an image.

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3
Q

What are the two types of light receptive cells called?

A

Rods
Cones

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4
Q

What is the difference between rods and cones?

A

Rods can detect light, not colour whereas cones can detect colour

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5
Q

What controls the amount of light entering the eye?

A

The irish

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6
Q

How does the Iris control the amount of light entering the eye?

A

The muscles in the iris adjust the size of the pupil

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7
Q

What do circular muscles do in pupil constriction?

A

Contract

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8
Q

What do radical muscles do in pupil constriction?

A

Relax

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9
Q

What do circular muscles do in pupil dilation?

A

Relax

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10
Q

What do radical muscles do in pupil dilation?

A

Contract

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11
Q

The control of pupil size is a … …. Which involves …. …. …. …. …. …. …. ….

A

Reflex action which involves motor neurons of the automatic nervous system

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12
Q

Outline the structure and function of the cornea

A

Transparent outer covering of the eye
Refracts light entering the eye

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13
Q

Outline the structure and function of the iris

A

Pigmented ring of circular muscles and radical muscles
Controls the size of the pupil to alter how much light enters the eye

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14
Q

What is the pupil?

A

A hole in the iris centre that allows light rays to enter the eye

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15
Q

Outline the structure and function of the lens

A

Transparent, bi-convex structure
Suspensory ligaments attach the lens to a ring of ciliary muscle
Refracts light, focusing it into the retina

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16
Q

What is the function of the ciliary muscles and suspensory ligaments?

A

Change the shape of the lens (accommodation) to focus light onto the retina

17
Q

Outline the structure and function of the retina

A

Light sensitive layer composed of rod and cone cells
Converts light energy into neural signals which are sent to the brain via the optic nerve

18
Q

What are rod cells?

A

Cells in the retina that are sensitive to low light intensity (dim light)

19
Q

What are cone cells?

A

Cells found in the retina that are sensitive to high light intensity (bright light) and can detect different colours

20
Q

What is the function of the optic nerve?

A

It transmits nerve impulses to the brain from the retina

21
Q

Describe how dim light affects the size of the pupil (5)

A

Light receptors detect dim light
Circular muscles relax
Radical muscles contract
Pupil dilates
More light enters the pupil

22
Q

Describe how bright light affects the size of the pupil (6)

A

Light receptors detect bright light
Circular muscles contract
Radical muscles relax
Pupil contracts
Less light enters the pupil

23
Q

Why is the iris reflex important?

A

It prevents bright light from damaging the retina

24
Q

What is accommodation?

A

Process by which the elastic lens change sits shape (with the aid of ciliary muscles and suspensory ligaments) to focus on near or distant objects
Light is focused onto the retina

25
Q

Describe how the eye focuses on near objects (6)

A

Near object
Ciliary muscles contract
Suspensory ligaments slacken
Lens become more convex (more rounded )
Light is refracted more
Light rays focuses onto the retina

26
Q

Convex

A

Rounded

27
Q

Describe how the eye focuses on distant objects (6)

A

Distant objects
Ciliary muscles relax
Suspensory ligament tighten
Lens become less convex (less rounded)
Light is refracted less
Light rays focused onto the retina

28
Q

What is long-sightedness?

A

Can focus on distant objects clearly but cannot focus on near objects

29
Q

What are the causes of long-sightedness? (3)

A

Eyeball is too short
Lens is less elastic (usually age-related)
Therefore light rays are not focussed onto the retina, instead of converging behind the retina

30
Q

How is long-sightedness treated? (3)

A

Using a convex lens (causes light rays to converge) in glasses or contact lenses
Replacements lenses
Laser eye surgery

31
Q

What is short-sightedness?

A

Can focus on near objects clearly, cannot focus on distant objects

32
Q

What are the causes of short-sightedness? (3)

A

Eyeball is too long
Lens is too thick and too rounded
Therefore light rays are not focussed onto the retina instead converging in front of the retina

33
Q

How is short-sightedness treated? (3)

A

Using a concave lens (causes light rays to diverge) in glasses or contact lenses
Replace,ent lenses
Laser eye surgery

34
Q

What are cataracts ? (2)

A

A cloudy patch forms on the lens of the eye which negatively affects vision
Vision becomes blurry, difficult to see the intensity of colours, problems with glare etc.

35
Q

How are the cataracts treated?

A

The clouded lens is exchanged for a synthetic lens during surgery

36
Q

What is colour-blindness?

A

A deficiency of the eye that makes it difficult to distinguish between colours

37
Q

What is the cause of colour-blindness?

A

Damage to cone cells in the retina

Topic 2- Cells & Control 📄 (10 decks)

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