Journey Through the Eye L01

Question 1

What is the first structure of the eye a photon encounters?

Answer 1

Tear film

Question 2

What is the tear film?

Answer 2

A thin film of fluid

Question 3

What is the tear film made up of?

Answer 3

Fat, mucus and water

Question 4

After encountering the tear film what is the next structure a photon or light ray will encounter?

Answer 4

The cornea

Question 5

What is the opaque part of the cornea called?

Answer 5

Sclera

Question 6

At the front of the eye how is the sclera modified?

Answer 6

It is modified to be the transparent cornea.

Question 7

Where do the sclera and limbus meet each other?

Answer 7

At the limbus

Question 8

What is between the cornea and lens?

Answer 8

Anterior chamber

Question 9

What two aspects of the eye focus the light?

Answer 9

The cornea and lens

Question 10

Where does most of the focussing of light occur?

Answer 10

Cornea - in fact this focusses around 3/4 of the light.

Question 11

What is the lens responsible for?

Answer 11

Allowing us to see at different distances - accommodation

Question 12

What is the retina?

Answer 12

The retina is a sheet of nerve cells that lines the back of the eye. (2/3rds of the posterior globe)

Question 13

What does the retina do?

Answer 13

Converts the photon into an electrical signal which is what is analysed by the brain

Question 14

What does every cell in the body require?

Answer 14

Oxygen and nutrients

Question 15

How do cells typically gain the oxygen and nutrients they need?

Answer 15

By being close to blood vessels so oxygen and nutrients can be diffused into the cell.

Question 16

Where does the retina get its nutrients from?

Answer 16

Choroid. This is a thick layer of blood vessels.

Question 17

What are the two exceptions where we don’t have blood vessels supplying nutrients?

Answer 17

The cornea and the lens.

Question 18

What is used to supply nutrients to the cornea and lens?

Answer 18

The aqueous humour

Question 19

Why are there no blood vessels to supply nutrients to the cornea or lens?

Answer 19

Because they have to be entirely transparent to allow light through and having blood vessels would obviously stop that.

Question 20

Where is the aqueous humour present?

Answer 20

Anterior chamber

Question 21

What is aqueous humour made by?

Answer 21

Ciliary body

Question 22

Where is aqueous humour drained from?

Answer 22

Canal of schlemm

Question 23

What substance is the posterior chamber filled with?

Answer 23

Vitreous humour - gelatinous substance

Question 24

What is vitreous humour?

Answer 24

A form of connective tissue

Question 25

Muscles in the iris can contract altering what?

Answer 25

The size of the pupil

Question 26

Why effect does changing the size of the pupil have?

Answer 26

It changes the amount of light that reaches the back of the eye.

Question 27

Muscles in the ciliary body contract altering what?

Answer 27

The shape of the lens.

Question 28

Why is it beneficial to be able to alter the shape of the lens?

Answer 28

It allows for accommodation - this allows us to focus on objects at different distances.