5.2.3 The eye

Question 1

What is the eye?

Answer 1

sense organ
containing receptor sensitive to light intensity + colour

Question 2

Accommodation

Answer 2

process of changing the shape of the lens to focus on near or distant objects

Question 3

Structure relate to function: retina

Question 4

Structure relate to function: optic nerve

Question 5

Structure relate to function: sclera

Question 6

Structure relate to function: cornea

Question 7

Structure relate to function: iris

Question 8

Structure relate to function: ciliary muscles + suspensory ligaments

Question 9

What are the light rays from close objects like?

Answer 9

spread out
diverging strongly

Question 10

What are the light rays from distant objects like?

Answer 10

travelling in almost parallel rays

Question 11

What happens when we try to focus on near objects?

Answer 11

• ciliary muscles contract
• suspensory ligaments loosen
• lens = thicker (more curved)
• reflects light rays strongly

Question 12

What happens when we try to focus on distant objects?

Answer 12

• ciliary muscles relax
• suspensory ligaments are pulled tight
• lens = pulled thin
• reflects light rays only slightly

Question 13

How is the light that enters the eye focused?

Answer 13

by refraction

Question 14

How does the eye adapt to bright light?

Answer 14

• circular muscles ** contract**
• radial muscles relax
• pupil constricts

Question 15

Why do we have an iris reflex?

Answer 15

• too much light (bright)
• can damage retina

Question 16

How does the eye adapt to dim light?

Answer 16

• circular muscles ** relax**
• radial muscles contract
• pupil dilates