Eye Flashcards
1
Q
Sclera
A
- white outer covering about 5/6 of eyeball
- made of dense fibrous connective tissue and elastic fibers
- functions are ortection of the internal structures and to help maintain the shape
2
Q
Choroid
A
- forms approx 2/3 of uvea (absent at the optic nerve)
- contains blood vessels supplying all the internal structures of the ey with oxygen and nutrients
3
Q
Tapetum lucidum
A
- present in most mammals except for the pig and man
- it is triangular area of iridescent cells ( refectory light in the dark) lyin* where the optic never leaves the eye
- size and colour varies with species
- function is to reflect light back to ohtotrecotors cells of the retina to improve night vision
4
Q
Retina
A
- function is to transfer info from photoreceptors to brain
- includes the fovea- a small depression where visual acuity is highest
- innermost layer of eye, made your of different cells
- layer of pigmented cells
- photoreceptors cells ( rods and cones, absent in blind spot )
5
Q
Optic nerve
A
- transmits in for via nerve impulses from the photoreceptors cells to the brain
- join the eye at the optic disc or blind spot
- contains no photoreceptors cells
6
Q
Vitreous humour
A
- found within posterior chamber that lies between the iris and retina
- jelly-likeclearsubstance made up of mucopolysaccharide called hyaluronic acid some salt and 99% water
- functions are to maintain the shape of the eye and supply the structure of the posterior chamber with nutrient
7
Q
Extrinsic muscles
A
- eyeball is well supplied with extrinsic muscles including the medial and lateral rectus muscle
- allow animal to look in different directions without it turning its head
8
Q
Cornea
A
Covers 1/6eyebalx formed curved transparent part of eye
- has relatively poor blood supply but is well supplied with sensory nerve fibers
- outer surface is covered in protective layer of squamous epithelium known as conjunctiva
- cornea function is to refract light to help focus it onto the retina
9
Q
Aqueous humour
A
- found within the anterior chamber between cornea and iris
- watery liquid secreted by the cilited body and drains out vid the limbus at the same cornea-clearly junction
- similar in composition to blood plasma but only contains a trace of protein and no antibodies
- the function are to maintain the shape of the anterior chamber and supply these structures with nutrients
10
Q
Iris
A
- anterior continuation of the ciliary body
- contains both circular and radially arranged smooth muscle fibers whose function is to constrict or dilate the pupil thereby controlling the amount of light entering the eye
- bright light condition the muscle of the iris relax to allow the pupil to close and dim in lightthey contrac5 to open the pupil and let in more light
- nerve supply to the iris is from the oculomotor nerve and it also receives both sympathetic and parasympathetic nerve fibers
- iris contains pigmented cells which gives the iris its characteristics range of colours
11
Q
Lens
A
- transparent bioconversion disc whose function is to focus light onto the retina at the back of the eye
- tissue of the lens is elastic and its shape can be altered by contraction of the ciliary muscles around it
-when an object is close the lens is thick and fat ie more curved
When an object is far away lens is thin and flat or less curved
12
Q
Pupil
A
- aperture formed by the free edge of the iris
- diameter of the pupil is controlled by the contraction of the muscles of the iris and this is controlled how much light enter the eye
- shape varies by species
13
Q
Suspensory ligaments
A
- continuation of the ciliary body, they form a circular support around the periphery of the lens
- hold lens in place
- tension controlled by the ciliary muscles to change shape of lens to cpus vision
14
Q
Ciliary body
A
- thickened part of the uvea protecting towards the ventre of the eye
- contains smooth muscle fibers known as the ciliary muscles
These are responsible for controlling the shape of the lens
15
Q
Part of eye and associated structures
A
Eyelids
Eyeball
Extrinsic muscles
