The eye

Question 1

cornea

Answer 1

transparent area on the anterior surface of the eye

Question 2

Where are the two eyelids connected?

Answer 2

The lateral angle of the eye

Question 3

How does light enter the eye?

Answer 3

It passes through the cornea and the pupil

Question 4

What is the lacrimal caruncle?

- what does it do?

Answer 4

• small, reddish body at the medial angle of the eye

- produces thick secretion that cause gritty deposits that appear after sleep

Question 5

What is the palpebral fissure?

Answer 5

The gap that separates the free margins of the upper and lower eyelids

Question 6

What is conjunctiva, and what is it made of?

Answer 6

• mucous covered specialized, stratified squamous epithelium

- covers the inner surfaces of the eyelids and the outer surface of the eye

Question 7

What are tarsal glands?

Answer 7

• on inner margin of the eye lid

- secrete lipid rich product that keeps the eyelids from sticking together

Question 8

What is palpebral conjunctiva?

Answer 8

covers the inner surface of the eyelids

Question 9

bulbar conjunctiva

Answer 9

covers the anterior surface of the eye

Question 10

fornix

Answer 10

a pocket created when the palpebral conjunctiva becomes continuous with the bulbar conjunctiva

Question 11

What does the lacrimal apparatus do and what does it consist of?

Answer 11

• produces, distributes, and removes tears

1) lacrimal gland
2) paired lacrimal canaliculi
3) lacrimal sac
4) nasolacrimal duct

Question 12

What are the three layers of the wall of the eye?

Answer 12

1) outer fibrous layer
2) intermediate vascular layer
3) deep inner layer

Question 13

What does the fibrous layer of the eye consist of? What is its function?

Answer 13

• cornea and white sclera (continuous and connect at the corneoscleral junction)
• protect the eye, attach to extrinsic eye muscles, contains cornea

Question 14

What does the vascular layer consist of?

What is its function?

Answer 14

• blood vessels, lymphatic vessels, intrinsic muscles of eye (iris, ciliary body, choroid)
• route for bv’s and lymphatic supply, regulate amount of light that enters, secreting and absorbing aqueous humor, controlling the shape of the lense

Question 15

What does the inner layer of the eye consist of? What is its function?

Answer 15

• retina

- absorbs light, photoreceptors

Question 16

What is the ciliary body?

Answer 16

Thickened region that bulges into the interior of the eye

- a ring of fibres holds the lens in place behind the pupil

Question 17

What does the body of the iris consist of?

Answer 17

Highly vascular, pigmented loose connective tissue

- anterior surface has no epithelial covering; instead, incomplete layer of fibroblasts and melanocytes

Question 18

What is the ciliary zonule?

Answer 18

Attaches to the tips of the ciliary processes

- connective tissue fibres hold the lens posterior to the iris and cantered on the pupil

Question 19

What is the ora serrata?

Answer 19

Jagged anterior edge of the neural layer of the retina

- outer pigmented layer of the retina continues anteriorly across the posterior surface of the iris

Question 20

Where is the highest concentration of photoreceptors?

Answer 20

Fovea central is (at the macula)

Question 21

What is accommodation?

Answer 21

We focus images on the retina by changing the shape of the lens to keep the focal distance constant and give us clear vision

Question 22

What is the near point of vision?

Answer 22

The inner limit of clear vision for close objects, determined by the degree of elasticity in the lensw

Question 22

What is the near point of vision?

Answer 22

The inner limit of clear vision for close objects, determined by the degree of elasticity in the lensw

Question 23

What is the function fo the pigmented layer of the retina?

Answer 23

• prevents light from bouncing back and producing visual “echoes”

Question 24

What is in the neural layer of the retina?

Answer 24

Photoreceptors, supporting cells and neurons that do preliminary processing (ganglion cells)

Question 25

Where do the axons of ganglion cells converge at?

Answer 25

The optic disc (aka the blind spot)

Question 26

Which cells are for seeming dimly lit rooms/black and white?Which are for colour/more intense light?

Answer 26

Rods, cones

Question 27

Where are the bipolar cells located?

Answer 27

Rods and cones synapse with neurons called bipolar cells

Question 28

What do amacrine cells do?

Answer 28

Inhibit communication between photoreceptors and ganglion cells thereby altering the sensitivity of the retina

Question 29

What is the visual pigment a derivative of?

Answer 29

Rhodopsin (visual purple)

- consists of opsin bound to the pigment retinal

Question 30

What colour wavelength is rod opsin most sensitive to? What are the three different colours of cones?

Answer 30

Blue-green, blue green and red

Question 31

How are photoreceptor gated channels kept open?

Answer 31

(cGMP) cyclic guanosine monophosphate, because channel is open, the membrane potential is approximately -40mV and constantly releasing neurotransmitters/sodium across synapses to bipolar cells

Question 32

Where do the optic nerves reach the diencephalon?

Answer 32

The optic chiasm

Question 33

Where does visual information travel from the diencephalon through the projection fibres?

Answer 33

The occipital cortex