eye COPY

Question 1

name the structures that the eye contains

Answer 1

retina, lens, cornea, pupil/iris, ciliary muscle, suspensory ligaments

Question 2

what is the function of the retina

Answer 2

Contains the light receptors, which trigger electrical impulses to be sent to the brain when light is detected.

Question 3

what is the function of the lens

Answer 3

Refracts light to focus it onto the retina. The amount of refraction can be adjusted by altering the thickness and curvature of the lens.

Question 4

what is the function of the cornea

Answer 4

Refracts light as it enters the eye (by a fixed amount).

Question 5

what is the function of the pupil/iris

Answer 5

The iris relax or contract to adjust the size of the pupil. Controls how much light enters the pupil.

Question 6

what is the function of the ciliary muscle

Answer 6

Adjust the shape of the lens to make it more or less curved, so as to increase or decrease the refraction of light. These changes in the shape of the lens allow light to be focused at varying distances.

Question 7

what is the function of the suspensory ligaments

Answer 7

Slacken or stretch as the ciliary muscles contract or relax, to adjust the thickness and curvature of the lens.

Question 8

what is the retina

Answer 8

The lining of the back of eye containing two types of light receptor cells. Rods are sensitive to dim light and black and white. Cones are sensitive to colour.

Question 9

what is the lens (of the eye)

Answer 9

Transparent, bi-convex, flexible disc behind the iris. It is attached to the ciliary muscles by the suspensory ligaments.

Question 10

what is the cornea

Answer 10

Tough, transparent covering over the front part of the eye. Convex in shape.

Question 11

what is the pupil

Answer 11

Hole in the middle of the iris.

Question 12

what is the iris

Answer 12

Coloured part of the eye that contains muscles.

Question 13

what are the ciliary muscles

Answer 13

Muscles connected to the lens by suspensory ligaments.

Question 14

what are the suspensory ligaments

Answer 14

Connect the ciliary muscles to the lens and hold the lens in place.

Question 15

what is the usual near and far point of the human eye

Answer 15

usually the near point of the human eye is approximately 25cm and the far point is infinity. the eye can focus on objects between the near point and the far point. the distance between these points is the range of vision.

Question 16

what is long sight caused by

Answer 16

it is caused by the eyeball being too short, or the eye lens being unable to focus.

Question 17

what is short sight caused by

Answer 17

it is caused by the eyeball being too long, or the eye lens being unable to focus

Question 18

how does long sight present itself (and what can be done)

Answer 18

Someone with long-sightedness can see distant objects clearly, but cannot focus properly on near objects. This is because the lens focuses the sharpest image behind the retina, instead of on it. This defect is often age-related, and due to a loss of elasticity in the lens. It is corrected by putting a convex lens in front of the eye.

Question 19

how does short sight present itself (and what can be done)

Answer 19

Someone with short-sightedness can see near objects clearly, but cannot focus properly on distant objects. This is caused by the eyeball being elongated, so that the distance between the lens and the retina is too great. It can be corrected by placing a concave lens in front of the eye.

Question 20

describe how the shape of the lens is changed for distant objects

Answer 20

the ciliary muscles relax, the suspensory ligaments stretch and the shape of the lens is thin - less convex.

Question 21

describe how the shape of the lens is changed for nearby objects

Answer 21

the ciliary muscles contract, the suspensory ligaments slacken and the shape of the lens is fat - more convex.

Question 22

what are lasers

Answer 22

lasers are a concentrated source of light

Question 23

what can lasers be used for

Answer 23

lasers can be used for cutting, cauterising and burning. lasers can be used in eye surgery, to correct visual defects.

Question 24

what is similar between the structure of the eye and the camera

Answer 24

in the eye the image is brought to focus on the retina by changing the shape of the lens, in a camera the image is brought to focus on the film by varying the distance between the film and the lens

Question 25

what part of the eye is the equivalent of the film in a camera

Answer 25

the film in a camera is the equivalent of the retina in the eye