THE EYE

Question 1

tough outer coat that protects the eye?

Answer 1

sclera

Question 2

layer of the eye that contains blood vessels, it nourishes the eye?

Answer 2

choroid

Question 3

front portion of the eye, convex in shape, it bulges outside. light enetrs the eye through this part?

Answer 3

cornea

Question 4

Coloured part of the eye, muscular diaphragm found behind the cornea. It regulates the amount of light entering the eye by adjusting the size of the pupil?

Answer 4

iris

Question 5

Hole in the middles of the iris. The size of the pupil increases or decreases depending
on the amount of light entering the eye?

Answer 5

pupil

Question 6

Made of transparent, jelly-like substance which is made of proteins. It is held in
position by the ciliary muscles and suspensory
ligaments?

Answer 6

lens

Question 7

Thick liquid which fills the area between the cornea and the lens. It prevents the eye
from collapsing due to changes in atmospheric pressure?

Answer 7

aqueas humor

Question 8

Membrane with a large number of 2 types of light sensitive receptor cells called rods
and cones/dect colour?

Answer 8

retina

Question 9

The main nerve through which nerve impulse from receptor cells in the retina are sent
to the brain?

Answer 9

optic nerve

Question 10

Jelly-like substance in the space between lens and retina, helps to maintain the shape
of the eye?

Answer 10

vitreous humor

Question 11

Small region of the eye where the optic nerve enters the eye . It is insensitive to
light

Answer 11

blind spot

Question 12

forming an image?

Answer 12

• Light passes through the eyeball to the retina.
• It is refracted (the rays are bent) by the cornea and lens, so that the light is brought to a focus on the retina.
• As a result of refraction the image on the retina is inverted.
• The brain interprets the image the right way up.

Question 13

what is accomodation?

Answer 13

The changes that take place in the eye to allow us to focus on near and far objects is called
accommodation.

Question 14

what happens to the cilary muscles when a object is near?

Answer 14

contract

Question 15

what happens to the suspenosry ligaments when a object is near?

Answer 15

slackened

Question 16

what happens to the lens shape when a object is near?

Answer 16

fat

Question 17

what happens to the cilary muscles when a object is distant?

Answer 17

relax

Question 18

what happens to the suspenosry ligaments when a object is distant?

Answer 18

stretched

Question 19

what happens to the lens shape when a object is distant?

Answer 19

thin

Question 20

In bright light the pupils are constricted.

Why?

Answer 20

To reduce amount of light entering the eye to avoid

damage to the retina

Question 21

In dim light the pupils are dialted.

Why?

Answer 21

To allow as much light as possible to fall on the

retina to maximise vision

Question 22

the iris?

Answer 22

The iris has circular and radial muscles that work
antagonistically to either constrict or dilate the pupil.

In bright light the circular muscles contract and radial muscles
relax, so the pupil is constricted.

In dim light the circular muscles relax and radial muscles
contract, so the pupil is dilated.

Question 23

iris reflex?

Answer 23

The constriction and dilation of pupils is an example of a reflex action.

Note: the reflex action of either eye controls the
constriction an dilation of pupils of both eyes (i.e. a bright
light shone into one eye will cause the pupils of both eyes to
constrict).