The Eye(Complete) Flashcards

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1
Q

What are the general features of the eye?

A

It is 2.5cm in diameter and is protected by the orbital( bony depressions) in the skull.
6 muscles control the movement of each eye.
There are 120 million light receptors in each eye( rods and cones) and they convert light into nerve impulses which are sent to the cerebrum of the brain to form a visual image.

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2
Q

What is the structure of the sclera?

A

The white part of the eye.
It is the outermost layer of the eye and is opaque.
It forms the cornea at the front of the eye.

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3
Q

What are the functions of the sclera?

A

To protect and give shape to the eyeball.

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4
Q

What is the structure of the choroid?

A

The dark and black middle layer with melanin.

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5
Q

What are the functions of the choroid?

A

To prevent internal reflection by absorbing any light rays that pass beyond the retina.

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6
Q

What is the structure of the retina?

A

The innermost layer of the eye.

Has rods and cones- photoreceptors.

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7
Q

What are the functions of the retina?

A

Converts light into nerve impulses so an image can form on the retina- generates impulses.

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8
Q

What is the structure of the fovea?

A

Part of the retina with cones only.

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9
Q

What are the functions of the fovea?

A

Provides detailed coloured vision in bright light.

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10
Q

What is the structure of the photoreceptors?

A

Sensory cells sensitive to light.
Contains rods and cones.
Contains the pigment rhodopsin which needs vitamin A.

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11
Q

What are the functions of the photoreceptors?

A

Rods:
Provide vision in dim light but only in black and grey.
Cones:
Provide detailed coloured vision in bright light.

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12
Q

What is the structure of the cornea?

A

Transparent front of eye with a curved surface to focus light.

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13
Q

What are the functions of the cornea?

A

To allow light to enter the light and bends it towards the retina.

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14
Q

What is the structure of the aqueous humour?

A

A clear liquid with salt.

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15
Q

What are the functions of the aqueous humour?

A

Contains the nutrients and oxygen for the cornea.

Maintains shape of cornea.

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16
Q

What is the structure of the vitreous humour?

A

Clear gel-like.

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17
Q

What are the functions of the vitreous humour?

A

Maintains the correct shape of the eyeball.

18
Q

What is the structure of the pupil?

A

Central opening of the iris.

19
Q

What are the functions of the pupil?

A

Allows light to enter the eyes:
Dilates in dim light to allow more light to enter the eyes.
Constricts in bright light to allow less light to enter the eyes.
Avoids dazzling effect.

20
Q

What is the structure of the iris?

A

Coloured sheet of muscle with melanin.

21
Q

What are the functions of the iris?

A

Controls the amount of light entering the eyes as follows:
Iris contracts in response to changing light intensity.
It changes the diameter of the pupil to allow more or less light to enter.

22
Q

What is the structure of the lens?

A

Transparent curved structure with biconvex shape.

23
Q

What are the functions of the lens?

A

To focus light onto the retina and carries fine adjustments to produce a sharp image.

24
Q

What is the structure of the ciliary body?

A

The ring of choroid tissue that contains the colliery muscle.

25
Q

What are the functions of the ciliary body?

A

Ciliary body:
Secretes the liquid that forms the aqueous humour.

Ciliary muscle:
Controls the curvature and focusing of strength of the lens.

26
Q

What is the structure of the suspensory ligaments?

A

Fibres that connect the ciliary body to the lens.

27
Q

What are the functions of the suspensory ligaments?

A

Holds the lens in place and is involved in the changing shape of the lens.

28
Q

What is the structure of the blind spot?

A

Part of the retina.

29
Q

What are the functions of the blind spot?

A

Does not generate a visual response as it has no rods or cones.

30
Q

What is the structure of the optic nerve?

A

Bundles of nerve fibres.

31
Q

What are the functions of the optic nerve?

A

To carry impulses to the cerebrum of the brain.

32
Q

When is the pupil constricted?

A

In bright light to allow less light ti enter the eye.

33
Q

When is the pupil dilated?

A

In dim light to allow more light to enter the eye.

34
Q

What is the fluid that fills the rear chamber of the eye?

A

The vitreous humour.

35
Q

What is the transparent covering in front of the cornea?

A

The conjunctiva.

36
Q

What is the function of the conjunctiva?

A

Protects against infection.

37
Q

What is the advantage of having 2 eyes?

A

3D vision.

Wider field of vision.

38
Q

The eyes of carnivores are located relatively close together at the front of the skull.
In herbivores they tend to be located to the side of the skull.
Suggest a benefit of either arrangement.

A

Herbivore- wider field of vision to detect predators.

Carnivore- to allow better judgement of distance.

39
Q

Apart from the eyelid, state one way in which the eye is protected from external damage.

A

Eyelashes.

40
Q

Name the part of the eye that contains a large amount of blood vessels.

A

Choroid layer.

41
Q

Where is the aqueous humour located?

A

Behind the cornea.

In front of the lens.

42
Q

Explain the importance of the eye reacting to bright light.

A

To prevent damage to the retina.