Anatomy and Physiology of the Eye- Intro

Question 1

what type of epithelium is found in the cornea?

Answer 1

simple squamous non-keratinised

Question 2

describe the stroma of the cornea

Answer 2

there is regularly arranged collagen with no blood vessels allowing light waves to pass through it so it is transparent.

Question 3

what sort of epithelium makes u the endothelium in the cornea?

Answer 3

single layer squamous epithelium, non keratinised.

Question 4

name the five tissue layers of the cornea

Answer 4

1. epithelium
2. bowmans membrane (basement membrane of corneal epithelium)
3. stroma
4. descemet’s layer
5. endothelium

Question 5

how does the cornea get its nutrition?

Answer 5

from the aqueous humour, the tear film and the blood vessels in the sclera.

Question 6

how is transparency of the cornea maintained?

Answer 6

> regular arrangement of collagen in stroma
no blood vessels
pump in the endothelial layer that actively keeps the aqueous layer out

Question 7

what happens if the endothelial cells of the cornea are lost?

Answer 7

the cells cannot regenerate so compensate by growing larger. if this passes a critical point then this becomes decompensated and holes begin to appear and aqueous humour spills in and the cornea becomes hazy.

Question 8

why is the cornea described as immune privileged?

Answer 8

there is a lesser chance that the cornea is recognised by the recipient as it is avascular so there is less chance of graft rejection.

Question 9

where is the aqueous humour produced?

Answer 9

behind the lens in the posterior chamber.

Question 10

where is the aqueous humour reabsorbed?

Answer 10

at the angle trabecular meshwork through schlemm’s canal.

Question 11

how many layers is in the retina?

Answer 11

10

Question 12

describe the fovea centralis

Answer 12

this is a point in the retina where the outer layers are pushed away that is packed with cones so there is maximum visual acuity.

Question 13

describe the lens

Answer 13

a transparent, crystalline biconvex structure

Question 14

what is the lens suspended by?

Answer 14

zonules (from the ciliary body)

Question 15

what is lens opacification commonly called?

Answer 15

cataracts

Question 16

what predisposes the lens to become opaque in later life?

Answer 16

its avascularity

Question 17

what are the functions of the tear film?

Answer 17

> prevents drying of the cornea
washes away foreign bodies
kills microbes with antibodies and lysosomes
provides smooth surface for refraction

Question 18

what layer of the tear film overlies the corneal epithelium?

Answer 18

mucous

Question 19

what composes the most superficial layer of the tear film?

Answer 19

oil

Question 20

what happens when the aqueous layer of the tear film evaporates and the oily layer and mucinous layer touch?

Answer 20

you feel discomfort and blink

Question 21

how can you see the tear film?

Answer 21

by staining it with a dye, fluorescein

Question 22

from where do the optic vesicles grow out of in embryological development?

Answer 22

the neural tube

Question 23

what happens when the optic vesicles reach the surface of the ectoderm?

Answer 23

a part gets pushed outwards forming two layers. a outer layer forms a layer of the retina and the other forms the other 9 layers of the retina.