The eye

Question 1

Function of the conjunctiva:

Answer 1

Protects the cornea from damage

Question 2

Function of the sclera:

Answer 2

Protects the eyeball from mechanical damage

Question 3

Function of the cornea:

Answer 3

Transparent
Most refraction of light occurs here

Question 4

Function of the Iris:

Answer 4

Adjusts the size of the pupil to maximise the amount of light getting through

Question 5

Function of the pupil:

Answer 5

Light enters here to pass to the lens

Question 6

Function of the lens:

Answer 6

Refracts light, focuses light rays on retina

Question 7

Function of the retina:

Answer 7

When stimulated - rods and cones initiate impulses in associated neurones

Question 8

Function of the aqueous humour:

Answer 8

Maintains the shape of the front of the eye

Question 9

Function of the vitreous humour:

Answer 9

Maintains the shape of the rear part of the eye & supports the lens

Question 10

Function of the fovea:

Answer 10

Rich in cones and gives the clearest daylight colour vision (does not contain rods)

Question 11

Function of the choroid:

Answer 11

Contain blood vessels which supply the retina & prevents the reflection of light through the eye

Question 12

Function of the optic nerve?

Answer 12

Transmits impulses from the retina to the brain

Question 13

Function of the blind spot:

Answer 13

Contains no light sensitive cells so there is no light sensitivity taking place here

Question 14

Function of the ciliary body:

Answer 14

Adjusts the shape of the lens to focus light rays

Question 15

Function of the suspensory ligaments:

Answer 15

Transfers tension in the wall of the eyeball to make the lens thinner

Question 16

What are the 4 components of eye accommodation?

Answer 16

Reflex
Convergence
Proximal & tonic accommodation

Question 17

What is the structure that links the ciliary body and the lens?

Answer 17

Suspensory ligaments

Question 18

The layer that prevents internal reflection of light in the eye:

Answer 18

Choroid

Question 19

The type of vision that makes 3D images possible:

Answer 19

Stereoscopic vision

Question 20

What are rods and cones?

Answer 20

Specialised photoreceptors

Question 21

What do rods and cones do?

Answer 21

Convert a light stimulus into a nerve impulse in their neighbouring neurones

Question 22

What 3 layers do the rods & cones make up?

Answer 22

Layer adjacent to the choroid
Layer of bipolar neurones
Layer of sensory cells

Question 23

What are sensory cells also known as?

Answer 23

Ganglion cells

Question 24

How is the optic nerve made up?

Answer 24

Axons of the ganglion cells group together to form the optic nerve

Question 25

What is the name for when 'many rods synapse with each bipolar neurone and many bipolar cells connect with each neurone of the optic nerve'?

Answer 25

Retinal Convergence

Question 26

Describe the definition of a Bipolar neurone:

Answer 26

A neurone with 2 extensions - an axon & a dendrite - that run from opposite sides of the cell body

Question 27

What is a consequence of retinal convergence?

Answer 27

The brain cannot distinguish which rod in a group sharing the same optic nerve has been stimulated

Question 28

What will this consequence result in?

Answer 28

Decreased visual acuity

Question 29

What do rods lack?

Answer 29

The ability to discriminate detail

Question 30

Where do cones usually synapse?

Answer 30

Single bipolar neurone & a single neurone of the optic nerve

Question 31

What does this synapse of cones mean?

Answer 31

Generates an impulse in the brain

Question 32

What does this impulse provide?

Answer 32

Gives high visual acuity

Question 33

What is an advantage of cones?

Answer 33

They can distinguish between points that are close together

Question 34

What is found packed into the membranes on the outer segment of the rods?

Answer 34

Rhodopsin - formed from the protein opsin combined with retinal (light absorbing compound)