Lab 9 - Eye dissection

Question 1

Which animal’s eye did we dissect

Answer 1

Sheep

Question 2

Why is there such a lot of adipose tissue around the eye

Answer 2

The space between the eye muscles and the bony wall of the orbit is filled with this adipose tissue. Its there for protection and acts as a cushion and insulator

Question 3

What are the extraocular muscles

Answer 3

• superior rectus – up
• superior oblique
• medial rectus
• lacteral rectus
• inferior oblique
• inferior rectus – down
• levator palpebrae superioris - runs along top of eye ball and sends tendons into eyelid

Question 4

Where is the cornea wider

Answer 4

Nasally

Question 5

What is found in sheep but not in man

Answer 5

Retractor bulbi

Question 6

What colour is musccle and fat

Answer 6

Muscle = brown
Fat = white

Question 7

What does the ora serrata represent, and why does it have this name

Answer 7

Flat bit of ciliary body merges with retina here – the transition zone. It is the junction between the ciliary body and the retina.
It is serrated as its covered with ciliary processes – is jiggered/folded/multi layered

Question 8

What nature does vitreous humour have

Answer 8

Viscous

Question 9

What type of tissue is vitreous humour an example of?

Answer 9

Connective tissue - collagen and proteoglycans

Question 10

What is its function of vitreous humour?

Answer 10

Helps support shape of eye, protection and transmits light to the retina

Question 11

Where is the only site of attachment of the retina

Answer 11

At the optic nerve head

Question 12

What does transduction of visual stimulus mean

Answer 12

Turns photons of light into neurobiological activity

Question 13

What is the function of such a tapetum lucidum

Answer 13

It reflects visible light back through the retina, increasing the light available to the photoreceptors contributes to night vision of some animals.

Question 14

Why is tapetum lucidum sometimes unevenly distributed

Answer 14

Purpose is just to reflect light in the eye so that more light can be gathered to make the image brighter so it doesnt have to be so well placed

Question 15

How does it appear where there is no tapetum on the posterior surface of the eye

Answer 15

Black

Question 16

What accounts for black colouration

Answer 16

Choroid

Question 17

What is function of choroid

Answer 17

Supply nutrients to outer retina

Question 18

How is the lens attached to the ciliary body

Answer 18

By suspensory ligaments

Question 19

Which lens surface is more curved

Answer 19

Cornea

Question 20

Why does the lens appear hard? Is this what it would be like in the living animal?

Answer 20

• When the animal is dead the lens is hard

- When the animal is alive the lens is soft due to the chemicals living in it

Question 21

What do the lens sutures represent

Answer 21

More layers of lens fibers are added to the outer portion of the lens

Question 22

What is the lens nucleus

Answer 22

Central part containing the oldest fibres present from birth

Question 23

What pathological condition results in a loss of lens transparency?

Answer 23

Cataract

Question 24

What feature distinguishes the pars plana and pars plicata

Answer 24

Pars plana is flat, pars plicata is pleated

Question 25

What are the two main functions of the ciliary body?

Answer 25

Produce aqueous humour – provide nutrients- feed lens + back of cornea with nutrients and oxygen. Back of cornea has corneal endothelial cells – need constant supply of oxygen – cornea avascular aqueous humour ( ultrafiltrated blood – takes h20 and nutrients out of blood – not white blood cells – enters into anterior chamber through pupil, bathing lens and cornea - continuously secreted by epithelail cells of ciliary body – what lines ciliary body – have epithelial cells – Includes trabecular framework and canal of Schlemm. Aqueous through trabecular framework and drained out of canal of Schlemm - Absorbing stray light – black box effect – not reflected back onto retina

Question 26

What is limbus

Answer 26

Exposed surface of eye

Question 27

What is drained at filtration angle

Answer 27

Aqueous humour

Question 28

What pathological condition results from inadequate drainage?

Answer 28

Glaucoma

Question 29

How do the epithelia of the ciliary body and posterior iris differ

Answer 29

The posterior surface of the iris is lined by simple, cuboidal pigmented epithelium (posterior pigmented epithelium). Whereas the ciliary body is lined with both pigmented and unpigmented epithelium.

Question 30

What is the function of the ciliary body epithelium?

Answer 30

Produces aqueous humor, which is responsible for providing oxygen, nutrients, and metabolic waste removal to the lens and the cornea, which do not have their own blood supply

Question 31

What is the function of the iris epithelium

Answer 31

- Helps to regulate the amount of light passing through to the retina – forms pupil – aperture stop - No light going through iris – absorb any light coming from front – doesnt go throught iris -double pigmented layer = absorb as much light as possible

Question 32

Describe cornea

Answer 32

continuous with sclera – white part of eye – contains densely packed irregular collagen fibres – perfectly perpendicular – allow light throught without bending it to much, made up of connective tissue

Question 33

What is limbus

Answer 33

Transition zone from the cornea to the sclera