Structure of the eye

Question 1

What is the job of the cornea and where is it located?

Answer 1

• The cornea is the outer layer of the eye
• It is completely transparent to let in max light - This means that it has no blood vessels and all of the oxygen that it needs for respiration is diffused in
• It causes light to refract (to focus the light)

Question 2

What is the job of the iris?

Answer 2

• Coloured part of the eye
• Controls the size of the pupil

Question 3

What is the pupil?

Answer 3

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

Question 4

What is the job of the lens?

Answer 4

• Can change shape un order to refract light to one point
• Allows it to always focus light perfectly onto the retina

Question 5

What is the job of the retina?

Answer 5

• Made up of 2 different receptor cells
• Translates light into conceivable images

Question 6

What is a cone cell?

Answer 6

• Receptor cells in the retina
• Allow us to see colour
• Don’t work well in low light conditions (cannot see colour when it is dark)

Question 7

What is a rod cell?

Answer 7

• Receptor cells in the retina
• More sensitive to light (allow us to see in lower lights)
• Only see in black and white

Question 8

What is the fovea and where is it located?

Answer 8

• The point on the retina which contains only cone cells
• The region where we try to focus light

Question 9

What is the job of the optic nerve?

Answer 9

• Transmits impulses from receptor cells to the brain

Question 10

What is the iris reflex (bright light)?

Answer 10

• Bright light can cause damage to the retina
• In bright light conditions, the pupil becomes “constricted” so that it limits the light passing through to the retina
• The circular muscles contract and the radial muscles relax

Question 11

What is the iris reflex (low light)?

Answer 11

• We need lots of light to be able to see in low light conditions
• The pupil becomes dilated
• Circular muscles relax and the radial muscles contract