Eye

Question 1

Function of cornea

Answer 1

• refracts light into the eye

Question 2

Function of iris

Answer 2

• iris reflex
• which controls amount of light which enters the eye
• (by adjusting pupil size)

Question 3

Function of pupil

Answer 3

• hole in iris
• lets light into the eye

Question 4

Function of choroid

Answer 4

• dark
• contains blood vessels + pigment cells
• pigment cells stops light being reflected inside eye

Question 5

Function of retina

Answer 5

• light-sensitive layer
• where light energy ➜ electrical energy (nerve impulses)
• contains rods + cones

Question 6

Function of rods and cones

Answer 6

• react to light
• producing impulses

Question 7

What do rods see

Answer 7

• black and white

Question 8

What do cones see

Answer 8

• red, green, blue
• (All colours)

Question 9

Function of lens

Answer 9

• focuses light onto retina
• accommodation

Question 10

Function of ciliary muscles

Answer 10

• change the shape of lens (accomodation)

Question 11

Function of suspension ligaments

Answer 11

• holds lens in place
• helps it change shape

Question 12

Function of optic nerve

Answer 12

• carries impulses from retina to brain

Question 13

Function of sclera

Answer 13

• tough outer layer of protection

Question 14

Function of fovea

Answer 14

• highest concentration of cones
• (so we have sharp central vision— where we look at objects directly for clearer vision)

Question 15

Function of blind spot

Answer 15

• area with no rods or cones
• where optic nerve leave eye

Question 16

What is the iris reflex for bright light

Answer 16

• circular muscles contract
• radial muscles relax
• pupil constricts

Question 17

What is iris reflex for dim light

Answer 17

• radial muscles contract
• circular muscles relax
• pupil dilates

Question 18

Iris reflex order

Answer 18

• stimulus = light intensity

➜

• receptor = retina

➜

• sensory neurons in optic nerve

➜

• unconscious part of brain

➜

• motor neuroses in nerve to iris

➜

• effector = iris muscles (radial + circular)

➜

• response = change in pupil size

Question 19

Define accommodation

Answer 19

• changes in the eye which allow us to see objects at different distances

Question 20

Accomodation for distant object

Answer 20

• lens becomes flat / less convex
• ciliary muscles relax
• suspensory ligaments pulled tight

Question 21

Accomodation for nearby object

Answer 21

• lens becomes more convex
• ciliary muscles contract
• suspensory ligaments slack