Special Senses 2

Question 1

Name the 3 layers of the eye

Answer 1

1. Outermost is the corneoscleral coat
2. Middle is the uveal tract (vascular coat)
3. Inner layer is the retina (nerve cells)

Question 2

Describe the shape of the lens

Answer 2

It is biconvex and elastic

Question 3

What exists in front of the lens

Answer 3

Two chambers filled with aqueous humor:

1. Anterior chamber
2. Posterior chamber

Question 4

What exists behind the lens

Answer 4

Large vitreal cavity filled with vitreous humor

Question 5

What is the conjunctiva

Answer 5

A thin, transparent mucous membrane

Question 6

Describe the layers of the conjunctiva

Answer 6

1. Stratified columnar epithelium with goblet cells

2. Lamina propria with loose connective tissue

Question 7

Name the 5 layers of the cornea

Answer 7

1. Epithelium
2. Bowman’s membrane (collagen)
3. Cornea stroma (collagen)
4. Descemet’s membrane (collagen)
5. Endothelium

Question 8

Describe the epithelium of the cornea

Answer 8

Non-keratinised stratified squamous

Question 9

What is the cornea stroma consisted of

Answer 9

Many layers of precisely orientated, hydrated collagen with each layer at roughly right angles to each other

Question 10

What is the sclera

Answer 10

Tough coat of collagen and elastic fibres

Question 11

What does the ciliary body contain

Answer 11

Smooth muscle that allows the lens to change shape

Question 12

How is excess fluid drained from the anterior chamber

Answer 12

It is drained via the canal of Schlemm into blood vessels

Question 13

What is the iris composed of

Answer 13

Mostly loose connective tissue with a layer of pigmented epithelium on its posterior surface (contains melanocytes)

Question 14

Name the muscles of the iris

Answer 14

1. Sphincter pupillae

2. Dilator pupillae

Question 15

Describe lens fibres

Answer 15

Long, thin cells that, as they mature, lose their nuclei and most organelles

Question 16

What is the subcapsular epithelium

Answer 16

Layer of simple cuboidal epithelium that covers the lens anteriorly

Question 17

What is the retina

Answer 17

A complex, thin layer of nervous tissue lining the inner eye

Question 18

What does each retina contain

Answer 18

1. 130 million rods

2. 6.5 million cones

Question 19

What does each rod contain

Answer 19

Rhodopsin, a light-sensitive pigment

Question 20

What does each cone contain

Answer 20

One of three opsin pigments, sensitive to either: red, green, or blue light

Question 21

Are rods and cones evenly distributed

Answer 21

No

Question 22

Describe the distribution of rods

Answer 22

They predominate away from the fovea but are absent in the fovea

Question 23

Where does the fovea lie

Answer 23

At the centre of the optical axis, on the retina, at the centre of the macula lutea

Question 24

What is at the centre of the fovea

Answer 24

The foveola, where the retina thins and is avascular

Question 25

What is the optic disc

Answer 25

The site where the axons of the retinal ganglion cells exit the eye to form the optic nerve

Question 26

What do the retinal ganglion cells have to pass through to form the optic nerve

Answer 26

Through the sclera; specifically the lamina cribrosa

Question 27

Why is the optic disc also known as the blind spot

Answer 27

It lacks photoreceptors