Eye Anatomy Flashcards
Eye
description? how many layers? what are they?
2.5 diameter wall of eyeball consists of 3 layers: -fibrous tunic: outer layer -vascular tunic: middle layer -retina: inner layer
Fibrous Tunic
composed of ? (2)
cornea
sclera
Cornea
description? what does it do?
transparent covering of iris
admits & refracts light into eye- helps focus light onto retina
(bulges out)
Sclera
description? what does it do?
(cornea turns into this)
“white” of the eye- dense connective tissue
provides shape to eyeball (outer layer)
attachment for eye muscles
Vascular Tunic (Uvea) composed of ? (3)
(called Uvea bc of UV light)
choroid
ciliary body
iris
Choroid
function? location? description? contains? which do what?
lines sclera
posterior portion of tunic
vascular
contains melanocytes- appears black/brown
-prevents reflection & scattering of light
Ciliary body
anterior portion of tunic contains melanocytes (dark brown appearance) parts: -ciliary processes -ciliary muscle
ciliary processes definition?
vascular folds of internal surface of ciliary body
- secretes aqueous humor (watery)
ciliary muscle definition ?
(connected to iris)
circular band of smooth muscle
-muscle contraction changes lens shape
-adapts for near or far vision
iris
description? how is color determined? location? made of? function?
colored portion of eyeball -determined by amount of melanin attached to ciliary processes made of melanocytes & smooth muscle fibers regulates amount of light into eyeball
pupil
opening in center of iris\
coloboma
irregular shaped iris
-pupil is NOT circular
(does not affect sight, happens in fetus)
heterochromia iridum
2 different colored iris
EX: blue and green eye
Lens, is it part of vascular tunic?
No, its not a part of the vascular tunic, it only sits in that area
Lens
description?
contains?
function?
(hard & semi-transparent)
behind pupil & iris
contains proteins - crystallins
-arranged in layers
lacks blood vessels
helps focus images on retina (help focus light on it)Interior eyeball cavities
whats divided into 2 cavities? what are they?
lens divides eye into 2 cavities : anterior cavity vitreous chamber (posterior cavity)
Anterior cavity
filled with? functions?
(watery)
filled w/ aqueous humor
-maintains shape of eyeball
-supplies oxygen & nutrients to lens & cornea
Posterior cavity aka Vitreous Chamber
(jelly)
Large cavity behind lens
-filled w/ vitreous body
-jelly-like substance
-maintain shape of eyeball
-keeps retina attached to choroidhow are the cavities held together?
held together by pressure
retina
description? consists of?
inner layer of eyeball, posterior 3/4 of eyeball
Consists of:
-pigmented layer- melanin
-neural (sensory) layer- processes visual data
Pigmented layer
(contains melanin)
helps absorb light rays
Neural (sensory) layer
(processes visual data) 3 layers: -Photoreceptors (rods & cones) -Bipolar cell layer -Ganglion cell layer
Other Areas on Retina (3)
Macula lutea
Fovea centralis
Optic disc
Macula lutea
description? location?
small flat spot
exact center posterior region of retina
visual axis of eye
Macular Degeneration (in macula lutea) where does it occur? what is it? what happens?
Degenerative disorder of retina
- occur in region of macula lutea
- lose acute vision, but have peripheral vision
Fovea centralis
location? contains? known for?
small depression in center of macula lutea
contains ONLY CONES
area of highest visual resolution
Optic disc
location? also known as?
where ganglion axons collect & exit eyeball as optic nerve 1 (joins which is why its #1)
AKA ‘blind spot’ - no rods & cones
Photoreceptors of Retina
function? what are the photoreceptors of retina? (2)
convert high rays to nerve impulse
- rods
- cones
rods
how many? allows/ does not allow?
120 million
enables to see dim light
does NOT provide color vision (dark & light adjustments)
cones
how many? types?
6 million
stimulated by bright light
3 types: blue (blue light), Green (green light), Red (right light)
-color vision results from combinations of the 3 types of cones being stimulated
Image Formation (3)
1) Refraction (bending) of light rays
2) Accommodation
3) Constriction (narrowing) of Pupil
Refraction (bending) of light rays
75% refraction through cornea
25% refraction through lens
image is inverted on retina
Accommodation
what is it? depends on? what controls it?
change in shape of lens depends on distance of object -distance objects: lens is flatter (ciliary muscles pull) -close objects: lens is more spherical ciliary muscle controls lens shape
Constriction (narrowing) of Pupil
circular muscles of iris control pupil diameter
Photopigments & vision
function? description? contain?
absorb light colored protein molecules initiates events for nerve potentials rods contain rhodosin -purplish color cones contains 3 different types of pigments photopigments contain: -opsin -retinal
opsin
protein molecule (photopigment contains this)
retinal
(photopigment contains this)
vitamin A derivative
-light absorbing part of photopigment
Brain pathway & visual fields
types of visual fields? binocular vision?
binocular vision- both eyes focus on 1 set of objects
Each eye visual field:
Nasal (Central) half
Temporal (Peripheral) half
Nasal (Central) half
light rays from nasal half will fall on the temporal half of the retina
Temporal (Peripheral) half
light rays from temporal half will fall on the nasal half of the retina
how is visual info conveyed ?
visual info from the RIGHT half of each visual field is conveyed to the LEFT side of the brain and vice versa
nearsighted/ farsightedness
another name for each?
nearsightedness - myopia
farsightedness - hyperopia
nearsightedness (myopia)
corrected with? what is it? where?
see close objects
focal point in front of retina
corrected w/ concave lens
farsightedness (hyperopia)
what is it? where? corrected with?
see far objects
focal point behind retina
corrected w/ convex lens
Astigmatism
definition?
either cornea or lens has irregular curvature
get multiple focal points- parts of image is unfocused or distorted
choroid , choroid coat
posterior 5/6 of middle (vascular) layer loosely joined to sclera
sclera
white part of outer (fibrous) layer
cornea
transparent anterior portion of outer layer
conjunctiva
inner lining of eyelid
lacrimal gland
secretes tears
vitreous humor
fills posterior cavity
optic disc
area where optic nerve exits eye
iris
smooth muscle that controls light entering the eye
aqueous humor
fills anterior and posterior chambers of anterior cavity of the eye
retina
contains visual receptors called rods & cones
suspensory ligaments, zonula fibers
connects lens to ciliary body
ciliary muscle
cause lens to change shape
structures & fluids through which light passes as it travels from the cornea to retina
cornea aqueous humor pupil of iris lens vitreous humor retina
what tissue is responsible for the toughness in the eye?
dense connective tissue
where’s aqueous humor in the eye?
anterior cavity (btwn cornea and lens)
function of dark pigment in choroid coat?
absorbs excess light
Extrinsic eye muscle: superior rectus
up and in
Extrinsic eye muscle: medial rectus
inward
Extrinsic eye muscle: inferior oblique
up and out
Extrinsic eye muscle: inferior rectus
down and in
Extrinsic eye muscle: lateral rectus
outward
Extrinsic eye muscle: superior oblique
Down and out
