homeostasis - the eye

Question 1

what is the eye

Answer 1

a sense organ

Question 2

what doe the eye contain

Answer 2

receptors which are sensitive to both the light intensity and color of light

Question 3

what is the cornea and what is the function

Answer 3

• its the transparent front of the eye
• it starts the focusing of the light rays

Question 4

what is the iris

Answer 4

• the colored part of the eye

Question 5

the light rays now pass through the lens, what is the job of the lense

Answer 5

focus the light rays onto the back of the eye

Question 6

what is one key feature of the lens

Answer 6

it can change its shape allowing us to focus on distant or near objects

Question 7

what does the retina contain and where is it found

Answer 7

found at the back of the eye, and it contains receptor cells for light

Question 8

what do the receptor cells allow us to detect

Answer 8

light intensity and light color

Question 9

what is the white part of the eye called

Answer 9

the sclera and this structure protects the eye

Question 10

what two things work with the lens

Answer 10

the ciliary muscles and the suspensory ligaments

Question 11

what do these things allow us to look at

Answer 11

allow us to focus on distant or near objects

Question 12

what is the pupil

Answer 12

the space in the centre of the iris which light passes through

Question 13

what is the job of the iris

Answer 13

to control the size of the pupil

Question 14

what is meant by accommodation

Answer 14

being able to change shape to allow the lens to focus on distant or near objects

Question 15

what surrounds the lens

Answer 15

ciliary muscle which is connected to the sense by fibres called suspensory ligaments

Question 16

how can the ciliary muscle change the thickness of the lens

Answer 16

by contracting or relaxing

Question 17

what is the effect is the lens is thicker

Answer 17

it can reflect light rays more strongly

Question 18

what happens when the ciliary muscles relax

Answer 18

the suspensory ligaments are puled tight

Question 19

key facts about light from distance objects

Answer 19

• it only needs to be focused a relatively small amount
• the lens is thin meaning the light rays are only slightly refracted

Question 20

key facts about light from near objects

Answer 20

• it needs to be focused a large amount
• the ciliary muscle contracts and causes the suspensory ligaments to loosen
• the lens is thicker and refracts the light rays more strongly

Question 21

what happens to people who can’t focus the light rays onto the retina

Answer 21

they become short or long sited

Question 22

what is long sight also called

Answer 22

hyperopia

Question 23

explain long sited people

Answer 23

• they have no problem focusing on distant objects but not near objects
• or the lens is less elastic and so can’t become thick enough to focus on near objects (mostly in elderly people)
• caused by a short eyeball

Question 24

how can people with long site be treated

Answer 24

glasses with convex lenses which partially focus the light before it enters the eye

Question 25

what is short sight also called

Answer 25

myopia

Question 26

explain people with short sight

Answer 26

- they can focus on near objects but not distant - the eye ball may be to long so light is focused inferno of the retina - also caused when the lens is too thick

Question 27

how can people with short site be traded

Answer 27

glasses with concave lenses to partially unfocus the light before It enter the eye

Question 28

instead of glasses what can people use

Answer 28

hard or soft contact lenses which sit on the eye ball and reflect the light like glasses

Question 29

how does laser surgery work

Answer 29

it can change the shape of the cornea so it refracts the light to a grater or lesser extent

Question 30

what can be used to replace the lens

Answer 30

an article one