Lab 9 - Eye dissection Flashcards
Which animal’s eye did we dissect
Sheep
Why is there such a lot of adipose tissue around the eye
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
What are the extraocular muscles
- 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
Where is the cornea wider
Nasally
What is found in sheep but not in man
Retractor bulbi
What colour is musccle and fat
Muscle = brown Fat = white
What does the ora serrata represent, and why does it have this name
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
What nature does vitreous humour have
Viscous
What type of tissue is vitreous humour an example of?
Connective tissue - collagen and proteoglycans
What is its function of vitreous humour?
Helps support shape of eye, protection and transmits light to the retina
Where is the only site of attachment of the retina
At the optic nerve head
What does transduction of visual stimulus mean
Turns photons of light into neurobiological activity
What is the function of such a tapetum lucidum
It reflects visible light back through the retina, increasing the light available to the photoreceptors contributes to night vision of some animals.
Why is tapetum lucidum sometimes unevenly distributed
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
How does it appear where there is no tapetum on the posterior surface of the eye
Black
What accounts for black colouration
Choroid
What is function of choroid
Supply nutrients to outer retina
How is the lens attached to the ciliary body
By suspensory ligaments
Which lens surface is more curved
Cornea
Why does the lens appear hard? Is this what it would be like in the living animal?
- 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
What do the lens sutures represent
More layers of lens fibers are added to the outer portion of the lens
What is the lens nucleus
Central part containing the oldest fibres present from birth
What pathological condition results in a loss of lens transparency?
Cataract
What feature distinguishes the pars plana and pars plicata
Pars plana is flat, pars plicata is pleated
What are the two main functions of the ciliary body?
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
What is limbus
Exposed surface of eye
What is drained at filtration angle
Aqueous humour
What pathological condition results from inadequate drainage?
Glaucoma
How do the epithelia of the ciliary body and posterior iris differ
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.
What is the function of the ciliary body epithelium?
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
What is the function of the iris epithelium
- 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
Describe cornea
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
What is limbus
Transition zone from the cornea to the sclera
