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orbital cavity
- fat and bone that surrounds eye
- maxilla, ethmoid, lacrimal, frontal, temporal bones
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palpebrae
eyelids and eyelashes
-
meibomian gland
oil gland that lubricates eyelids to keep them from sticking together
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tarsal plate
band of connective tissue that shapes eyelid
-
conjunctiva
mucous membrane that lines and moistens inner eyelid
-
lacrimal apparatus
- lacrimal gland and tubes
- produces tears
-
extrinsic eye muscles
fastest muscles in the eye
-
superior rectus
eye muscle that moves eye up
-
inferior rectus
eye muscle that moves eye down
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lateral rectus
eye muscle that moves eye out
-
medial rectus
eye muscle that moves eye in
-
superior oblique
eye muscle that moves eye down and out
-
inferior oblique
eye muscle that moves eye up and out
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fibrous tunic
- first layer
- cornea and clera
-
cornea
avascular transparent front of the eye
-
sclera
posterior white of the eye
-
uvea tunic
- aka vascular tunic
- middle layer
-
ciliary body
- thick ring of muscle that circles lens along with suspensory ligaments
- helps change shape of lens during accomodation
-
iris
- colored part of the eye
- only brown pigment
-
pupil
opening in middle of iris that lets light in
-
choroid
- black membrane that surround inner posterior eye
- prevents light from scattering
-
tapetum lucidem
greenish blue region in animals only that allows them to see clearly but not in color
-
nervous tunic
- aka retina
- yellow membrane in front of choroid
- most light sensitive part of eye
- several different cells: photoreceptors, ganglion cells, horizontal cells, bipolar cells
- 2 layers: inner and outer
-
photoreceptors
rods and cones that allow us to see light
-
ganglion cells
conduct APs
-
horizontal and bipolar cells
see shapes and patterns
-
outer retina
contains vitamin A and photopigment
-
inner retina
contains photoreceptors
-
rods
- dim light receptors
- night vision
-
cones
- bright light receptors
- day vision and color
-
macula lutea
- center of retina
- mostly cones
-
central fovea
- center of macula
- only cones
- region of clearest and sharpest vision
-
optic disc
- lateral to central fovea
- blind spot
- no rods or cones
-
lens
- avascular protein structure
- M&M shaped
- changes shape, causing image to be focused at focal point (directly on the retina)
- can get cloudy (cataracts)
-
anterior eye cavity
between cornea and lens
-
anterior chamber
- part of anterior eye cavity
- between cornea and iris
-
posterior chamber
- part of anterior eye cavity
- between iris and lens
-
aqueous humor
- watery liquid that fills entire anterior cavity
- produced by ciliary muscle
- maintains pressure inside eye
- drains through canal of schallen at junction of cornea and sclera
-
glaucoma
condition where aqueous humor is not properly drained/pressure builds
-
posterior eye cavity
between lens and retina
-
vitreous humor
- fills posterior cavity
- holds retina tight against choroid
- maintains pressure in the eye
- supports the lens
- bends light
-
imagine formation on the retina
- light passes through several regions to reach the retina and eventually the brain:
- cornea
- aqueous humor
- iris/pupil
- photoreceptors
- bipolar/horizontal cells
- ganglion cells
- retina
- optic disc
- optic nerve
- brain stem
- thalamus
- occipital lobe
-
focal point
- determined by the shape and length of the eyeball
- light bends and refracts to hight the retina at the focal point
- if focal point is in front or behind retina, glasses are needed
- image is upside down and backwards - corrected in occipital lobe
-
accomodation
- required to properly focus
- distant vision: ciliary muscle relaxes, suspensory ligaments contract, lens flattens, pupils dilate, eyes diverge
- close vision: ciliary muscle contracts, suspensory ligaments relax, pupils constrict, eyes converge
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presbyopia
- old sightedness
- lens loses elasticity and has trouble with accomodation
-
myopia
- near sightedness
- focal point in front of retina
-
hyperopia
- far sightedness
- focal point behind retina
-
astigmatism
- irregular curve of the cornea or the lens
- causes blurred vision
- 80% of the population
-
color blindness
- inability to see certain colors
- usually red and green
- men more than women
- 20% of the population
-
photopigment
- colored protein that will change its shape in response to light
- conducts APs
-
rhodopsin
- rods
- most common photopigment
- dim light
- contains retinal and opsin
- bright light: trans-retinal and opsin do not bind, rhodopsin not produced
- dim light: trans-retinal bends along 11th carbon, binds with opsin, rhodopsin produced
- moving from dim to bright straightens retinal (photopigment bleached)
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-
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retinal isomerase
enzyme that helps bending of retinal
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