exam 3 eye Flashcards
Describe the process and function of the lacrimal apparatus
Function: produces/collects tears (lacrimal fluid)
1) lacrimal gland produces tears
2) fluid is swept across eye
3) lacrimal canaliculi: From lacrimal puncti to nasalacrimal duct
4) nasolacrimal duct: drains tears into nasal cavity, eventually swallowed
what happens when someone cries
- tears overwhelm system
- too many tears to collect-overflow the eyelids
- nasolacrimal duct pours lots of tears into nasal cavity-runny nose
Function of medial rectus
moves eye medially (adducts)
Function of lateral rectus
moves eye laterally (abducts)
Function of Superior rectus
elevates eye and moves it medially
Function of Inferior rectus
depresses eye and moves eye medially
Function of superior oblique
depresses eye and moves eye laterally
Function of Inferior oblique
elevates eye and moves eye laterally
What is the lens and its function
biconvex, transparent structure inside eyeball
Function: Changes shape to focus light
Rounded= up close focusing
Flattened= further away focusing
What structures make up the fibrous tunic
sclera
Cornea
What structures make up vascular tunic
choroid
Ciliary body
Iris
What structures are neural?
fovea centralis
Neural layer of retina
Pigmented layer of retina
What is the sclera and its function
“whites” of the eye
Posterior 5/6
Function: Provide shape to the eyeball and protect the inner parts
What is the cornea and its function
curved, transparent structure
Anterior to iris and pupil
Anterior 1\6 of eye
Function: Admits and refracts light
What is the choroid and its function
dark brown membrane
Function: Contains many tiny blood vessels that help nourish the retina
What is the ciliary body and its function?
ring of smooth muscle tissue that surrounds the lens
Function: Produces aqueous humor.
When smooth muscles contract, suspensory ligaments relax to make lens more round
What is the iris and its function?
pigmented, colored part of eye (pupil in center)
Function: Regulates the amount of light entering the eye
Bright light= pupillary constriction
Low light= pupillary dilation
What 2 structures does the suspensory ligaments attach to
Lens and ciliary body
What is the retina
posterior 3/4 of eye
What is the pigmented layer and its function
outer layer adjacent to choroid. Single layer of cells. Function: Absorbs excess light to prevent reflection and glare. Also provides vitamin A
What is neural layer
inner layer
Function: Its photoreceptors receive light info and converts it into nerve impulses that are sent, via CN II to brain
Describe the 2 types of photoreceptors
rods- low lights, black and white vision
Cones- require more light. See in color
What is the optic disk/blind spot
- area where the optic nerve exits the eye
- area opening that allows axons to take info back to the brain
- contains no photoreceptors
Macula lutea
lateral to the optic disc, contains fovea centralis
fovea centralis
sharpest vision (only cones) where we want to focus our light, can see clearest
Describe the difference between normal vision, nearsightedness, and farsightedness?
normal- light is focused directly on the retina
Nearsightedness- visual image is focused in front of the retina
Farsightedness- visual image is focused behind retina
Describe clinical view: Detached retina
fluid collects between pigmented
What separates anterior and posterior chambers
Iris
What is aqueous humor
- Anterior cavity
- between cornea and lens
- removes waste
- supplies nutrients bc avascular
- continuously produced and replaced by ciliary body
what is vitreous humor
- posterior cavity
- helps maintain shape of eye
- not continuously produced
Describe the steps of visual info being processed
1) light rays enter eye through the cornea and are refracted
2) light rays are further refracted by the lens
3) light rays focus on retina
4) light ray info is converted to nerve impulses by photoreceptors
5) nerve impulses transmitted to the brain via CN II (optic nerve)
