The Eye

Question 1

Conjunctiva

Answer 1

A thin membrane protecting the sclera.

Question 2

Inflammation of the conjunctiva

Answer 2

Conjunctivitis

Question 3

Sclera (or sclerotic coat)

Answer 3

White of the eye. Tough and opaque (lets no light through). Holds the eye in shape

Question 4

Cornea

Answer 4

The transparent part of the sclera at the front of the eye. It lets light into the eye and bends it towards the retina

Question 5

Choroid

Answer 5

A dark coloured layer. It contains blood vessels to nourish the eye and black pigment (melanin) to absorb light in the eye. It ensures that there is no internal reflection inside the eye

Question 6

Retina

Answer 6

It is here that light receptors (rods and cones) are located

Question 7

Rods

Answer 7

Detect black and white
Found all over retina
Work in dim light

Question 8

Cones

Answer 8

Detect colours (red, green, blue)
Found mostly at fovea
Work in bright light

Question 9

Fovea

Answer 9

This area of the retina contains cones. It is the region of sharpest vision and it is here that images are focused.

Question 10

Yellow spot

Answer 10

An image that forms on the fovea

Question 11

Blind spot

Answer 11

Nerve fibres from the rods and cones are located on the surface of the retina . They impede incoming light rays and therefore obstruct vision. Nerve fibres leave the eye through a part of the retina called ** the blind**

Question 12

Optic nerve

Answer 12

Contains 126 axons that carry impulses from the rods and cones to the back of the brain (cerebrum)
Optic nerve is white

Question 13

Lens

Answer 13

An elastic, transparent structure. It changes shape to focus light on the retina. After light enters the pupil it hits the lens

Question 14

Ciliary muscle

Answer 14

Surrounds the lens and causes the shape of the lens to change when we look at near or cad objects. Connected to lens by suspenseful ligaments

Question 15

Accommodation

Answer 15

The changing of shape of the lens (reflex action)

Question 16

Iris

Answer 16

A coloured, muscular part of the eye. The amount of light entering the eye is controlled by the iris. May be pigmented with melanin

Question 17

Pupil

Answer 17

The opening of the iris. Lets light into the eye. Changing of shape of the iris is a reflex action carried out in response to light intensity

Question 18

Aqueous humour

Answer 18

A salt solution that holds the front of the eye in shape

Question 19

Vitreous humour

Answer 19

A more viscous fluid. It supports the eye by exerting an outward pressure on the eyeball

Question 20

External muscle

Answer 20

Th eye is moved by the use of six external muscles