Visual System 1

Question 1

What is the function of tears in the lacrimal system?

Answer 1

1. basal
2. reflex
3. emotional (crying)

Question 2

What is the afferent source in the lacrimal system?

Answer 2

cornea, cranial nerve V1 – ophthalmic trigeminal

Question 3

What is the efferent source in the lacrimal system?

Answer 3

parasympathetic

Question 4

What is the neurotransmitter in the lacrimal system?

Answer 4

acetylcholine

Question 5

What is produced by the lacrimal gland?

Answer 5

Tears

Question 6

How do tears drain?

Answer 6

through the two puncta, openings on medial lid margin

Question 7

How do tears flow?

Answer 7

through superior and inferior canalicul

Question 8

Where do tears gather?

Answer 8

Tear sac

Question 9

How do tears exit ear sac?

Answer 9

Through tear duct into nasal cavity

Question 10

Where is the lacrimal gland located?

Answer 10

within the orbit,

latero-superior to the globe

Question 11

Are tears only produced sometimes? What is it called?

Answer 11

It produces tear at a constant level,

even in the absence of irritation or stimulation - basal tear

Question 12

What do reflex tears refer to?

Answer 12

the increased tear production,

in response to ocular irritation

Question 13

What is the tear reflex pathway made up of?

Answer 13

1. afferent pathway
2. central nervous system
3. efferent pathway,
4. and the lacrimal gland

Question 14

What is the cornea innervated by?

Answer 14

-sensory nerve fibres via the Ophthalmic Branch of the Trigeminal Nerve

Question 15

What does the afferent pathway do?

Answer 15

trigeminal nerve relays signal to the central nervous system

Question 16

What is the efferent pathway mediated by?

Answer 16

parasympathetic nerve

Question 17

What is the lacrimal gland innervated by?

Answer 17

Lacrimal nerve (branch of ophthalmic nerve)

Question 18

What do the puncta form?

Answer 18

the opening of the superior and inferior canaliculi within the upper and lower eyelids

Question 19

What do both canaliculi converge as?

Answer 19

as one single common canaliculus,

and drain tear into the tear sac

Question 20

What does the tear film do?

Answer 20

1. Maintains smooth cornea-air surface
2. Oxygen supply to Cornea – normal cornea has no blood vessels
3. Removal of debris (tear film and blinking)
4. Bactericide

Question 21

What does the mucinous Layer corneal surface do?

Answer 21

Maintains surface wetting

Question 22

What is a healthy cornea covered by?

Answer 22

the tear film,

a thin layer of fluid

Question 23

What does the tear film maintain?

Answer 23

a smooth cornea-to-air surface

Question 24

What are the three layers of the tear film?

Answer 24

1. Lipid layer on the top
2. Aqueous Tear Film Layer in the middle
3. Mucinous layer

Question 25

What is the lipid layer responsible for?

Answer 25

protecting the tear film from rapid evaporation

Question 26

What is the lipid layer secreted by?

Answer 26

Meibomian Glands, | situated along the eyelid margins

Question 27

What does the aqueous tear film layer do?

Answer 27

1. delivers oxygen and nutrient to the surrounding tissue. | 2. contains factors against potentially harmful bacteria.

Question 28

What does the Mucinous layer do?

Answer 28

1. ensures that the tear film sticks to the eye surface. | 2. renders the surface of the eye "wettable".

Question 29

What do the mucin molecule in the mucinous layer do?

Answer 29

binding water molecules, | to the hydrophobic corneal epithelial cell surface

Question 30

What is the conjunctive?

Answer 30

Thin, transparent tissue that covers the outer surface of the eye

Question 31

What is the path of the conjunctiva?

Answer 31

- begins at the outer edge of the cornea - covers the visible part of the eye - lines the inside of the eyelids

Question 32

What is the conjunctive nourished by?

Answer 32

tiny blood vessels that are nearly invisible to the naked eye

Question 33

What is the anteroposterior diameter of the eye?

Answer 33

24mm in the adults

Question 34

What are the 3 layers of eye?

Answer 34

1. Sclera: hard and opaque 2. Choroid: pigmented and vascular 3. Retina: neurosensory tissue

Question 35

What is the sclera?

Answer 35

'white of the eye'

Question 36

What is the sclera made of?

Answer 36

tough, opaque tissue, high water content

Question 37

What is the function of sclera?

Answer 37

eye's protective outer coata and maintains shape

Question 38

What are the 5 layers of cornea?

Answer 38

1 – Epithelium 2 – Bowman’s membrane 3 – Stroma – its regularity contributes towards transparency 4- Descemet’s membrane 5- Endothelium – pumps fluid out of corneal and prevents corneal oedema

Question 39

What is the endothelium of the cornea function?

Answer 39

pumps fluid out of corneal and prevents corneal oedema

Question 40

What is the cornea?

Answer 40

transparent, dome-shaped window covering the front of the eye

Question 41

What is the water content of the cornea?

Answer 41

Low

Question 42

What is the purpose of the cornea?

Answer 42

Powerful refracting surface, providing 2/3 of the eye's focusing power

Question 43

Where and what is the uvea?

Answer 43

Vascular coat of eyeball and lies between the sclera and retina

Question 44

What are the three parts of the uvea? Are they connected?

Answer 44

1. iris 2. ciliary body 3. choroid - Intimately connected and a disease of one part also affects the other portions though not necessarily to the same degree

Question 45

What is the function of the choroid?

Answer 45

1. providing circulation to the eye | 2. shielding out unwanted scattered light

Question 46

What is the retina responsible for?

Answer 46

converting light into neurological impulses, | to be transmitted to the brain via the Optic Nerve

Question 47

Where is the choroid?

Answer 47

lies between the retina and sclera

Question 48

What is choroid made of and why is it good?

Answer 48

layers of blood vessels that nourish the back of the eye

Question 49

What does the iris do?

Answer 49

Controls light levels inside the eye similar to the aperture on a camera

Question 50

Where is the iris?

Answer 50

Round opening in the centre is the pupil

Question 51

What is the iris embedded with?

Answer 51

tiny muscles that dilate (widen) and constrict (narrow) the pupil size

Question 52

What is the structure of the lens?

Answer 52

- Outer acellular capsule - Regular inner elongated cell fibres – transparency - May loose transparency with age – cataract

Question 53

What is the function of the lens?

Answer 53

1. Transparency 2. Regular structure 3. Refractive Power 4. 1/3 of the eye focusing power - higher refractive index than aqueous fluid and vitreous 5. Accommodation (long and far vision) 6. Elasticity

Question 54

Does the cornea have blood supply?

Answer 54

Transparent so no blood vessels and receives nutrients via diffusion from her fluid at the outside and the aqueous humour at the inside