lesson 4 the structure of an eye

Question 1

as light hits the eye the first structure that it meets is what

Answer 1

the cornea

Question 2

it allow all the light to pass through , meaning the cornea is what

Answer 2

transparent and has no blood vessels

Question 3

why do we need the cornea

Answer 3

because it causes all the light that passes through it to refract

(Bend by a certain amount)

Question 4

what is the iris

Answer 4

the coloured bit of your eye

Question 5

the iris controls what

Answer 5

how big or small the pupil is

Question 6

what is the pupil

Answer 6

a gap in the middle of the iris that allows the light to pass through the lens

Question 7

what is the job of the lens

Answer 7

to refract light

(bend light)

Question 8

what can the lens also do

Answer 8

change its shape

Question 9

what does the lens changing shape do

Answer 9

allows it to control how strongly it refracts the light

Question 10

the lens changing its shape helps what

Answer 10

helps it focus its light perfectly on the retina

Question 11

where is the retina

Answer 11

at the back of th eye

Question 12

what is the retina made up which 2 different type of receptor cells

Answer 12

cone cells
rod cells

Question 13

cone cells are sensitive to what

Answer 13

the colour of light and allows us to see in colour

Question 14

rod cells are what

Answer 14

more sensitive to light and only allow us to see in black or white

Question 15

the fovea is what

Answer 15

a special spot on the retina which is full of only cone cells

Question 16

fovea is the region we what

Answer 16

try and focus light on so we can see things more clearly

Question 17

what does the optic nerve do

Answer 17

it takes all of the impulses generated by receptor cells and transmits them to the brain

Question 18

when you look at bright light, the intensity of the light can do what

Answer 18

cause damage to your retina

Question 19

how do you prevent damage to your retina from high light intensity

Answer 19

by iris reflex

Question 20

what does iris reflex do

Answer 20

controls the size of your pupil

Question 21

in high light intensity what happens to your pupil

(eg sun)

Answer 21

it gets smaller

Question 22

in low light intensity what happens to your pupil

(eg moon)

Answer 22

it gets larger

Question 23

when the pupils are small, what do we call it

Answer 23

constricted

Question 24

when the pupils are large, what do we call it

Answer 24

dilated

Question 25

to control the process of the iris reflex, the iris is made up of which 2 muscles

Answer 25

circular muscles

(around the inside of the iris)

radial muscles (around the outside of the iris)

Question 26

what do circular muscles do inside of the iris

Answer 26

they stretch around the pupils like circles

Question 27

what do radial muscles do inside the of the iris

Answer 27

the stretch from the inside to the outside

Question 28

in order for iris reflex to occur what in depth happens to the two muscles

Answer 28

the circular muscles need to contract and the radial muscles need to relax

(vice versa for dark light)