P2 - 5.4 Eyes 1 - Structure of the Eye + Iris Reflex

Question 1

what is a cross section of something

Answer 1

where something is spilt in half so we can see the insides

Question 2

when light first hits the eye what structure does it meet first

Answer 2

cornea

Question 3

why is the cornea transparent

Answer 3

to let light through

Question 4

True or False:
the cornea is not transparent

Answer 4

False it is transparent so it lets light through

Question 5

does the cornea have blood vessels

Answer 5

no because it is transparent

Question 6

True or False:
the cornea has no blood vessels

Answer 6

true

Question 7

which way does oxygen diffuse at the cornea

Answer 7

from the outside into the cornea

Question 8

why do we need the cornea

Answer 8

the cornea will bend/refract any light by a certain amount

Question 9

what is the coloured bit of your eye called

Answer 9

iris

Question 10

what colours can an iris be

Answer 10

blue, brown, green

Question 11

what does the iris do

Answer 11

control how big or small your pupil is

Question 12

what is the pupil

Answer 12

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

Question 13

what does the lens do

Answer 13

• it can change the shape of the light being refracted
• how strong the light being refracted is
• focuses light directly/perfectly onto retina

Question 14

what 2 type of receptor cells can be found in the retina

Answer 14

cone cells (colours)
rod cells (black + white)

Question 15

what do the cone cells do in the retina

Answer 15

detect colours in light
they aren’t very effective in low light

Question 16

what do rod cells do in the retina

Answer 16

detect black and white light and are very sensitive

Question 17

what are the main 5 structures of the eye

Answer 17

• cornea
• iris
• pupil
• lens
• retina
• fovea
• optic nerve

Question 18

describe the pathway of light in the eye

Answer 18

light hits the cornea which refracts it through the pupil in the iris hitting the lens which then perfectly refracts it to the retina

Question 19

what is the fovea

Answer 19

a special spot on the retina that is only full of cone cells (colour)

Question 20

where do we try to focus light on in the retina so we can see clearly

Answer 20

on the fovea (where light refracting meets)

Question 21

what is the optic nerve

Answer 21

the bit connected to the eye that takes all impulses generated by receptor cells to the brain

Question 22

what is the iris reflex

Answer 22

when your eye changes the shape of your pupil to prevent your eyes getting damaged

Question 23

Scenario:
You have looked at a bright light explain what happens to your eye

Answer 23

• constricted
• your circular muscles contract squeezing the pupil smaller
• radial muscles relax so they can be stretched longer

Question 24

True or False:
bright lights can cause damage to your retina

Answer 24

true

Question 25

Scenario:
You are in a dark room explain what happens to your eye

Answer 25

• dilated
• your circular muscles relax
• your radial muscles contract making them shorter and pulling the pupil open

Question 26

what are the 2 different types of muscles that cause your eye to contract/dilate

Answer 26

inside = circular muscles
outside = radial muscles (stretch from inside to outside)

Question 27

The eye is a sense organ. Which two stimuli are the receptor cells of the eye sensitive to?

Answer 27

• light
• colour

Question 28

When the pupil is very large, do we describe it as ‘constricted’ or ‘dilated’?

Answer 28

dilated

Question 29

When the pupil is very small, do we describe it as ‘constricted’ or ‘dilated’?

Answer 29

constricted

Question 30

What happens to the circular and radial muscles when the pupil constricts?

Answer 30

• circular muscle contracts
• radial muscle relaxes