Download The Eye - Downey Unified School District

The Eye
Maria Romo
Sophia Gomez
Christopher Oviedo
Period: 5
The Outer Tunic
● Cornea- light focus
● Sclera- white portion
of the eye
● Aqueous Humor
The Middle Tunic
★ Choroid Coatposterior ⅚ of globe
of eye and loosely
joins sclera
★ Ciliary bodythickest coat
The Middle Tunic cont.
● Suspensory
Ligaments- lens
further focuses light
● Iris- controls amount
of light entering the
back of the eye by
adjusting pupil size
● Pupil- hole in the eye
where light enters
The Inner Tunic
● Retina- light
sensitive inner lining
● Optic Disc- “Blind
Spot”
● Vitreous Bodyinternal structure of
the eye that helps
maintain shape
● Hyaloid Canalleads to optic nerve.
the Inner Tunic Cont.
● Macula Luteayellowish central part of
retina
● Fovea Centralisregion of the retina that
produces sharpest
vision
● Ganglion Nerves
Neurons
1. Visual receptors
a.
b.
cone- color sensory
rod- light sensory
i. more numerous
ii. more sensitive
Neurons cont.
2. Ganglion Neurons
●
●
●
●
M-Type (Alpha or Parasol)- Detect motion
P-Type (Beta or Midget)- Detect details in vision
Non-M, non-P type- Involved in color vision
Photoreceptive ganglion cells- Respond slowly to
light
Neurons cont.
● Optic Nerve- transmits sensory info
regarding brightness perception, red-green
color, contrast, and visual fields.
● Choroid- Vascular layer containing
connective tissue between the retina and the
sclera. Provides nourishment and O2 to the
outer layers of the retina
Accessory organs
● lids, brows, and lashesprotect the eye
● Conjunctival sac- mucous
membrane
● Lacrimal gland- produces
tears
● Lacrimal Sac- drains tears
from eye’s surface.
● Nasolacrimal duct- (tear
duct) excess tears flow
through from lacrimal sac.
Accessory organs cont.
Tarsal Glands- secretes
and collects mucous and
tears.
● Punctum Lacrimale
● Plica semilunaris
● Caruncula
Extrinsic Muscles
1. Superior Rectus- rotates eye up
and toward midline.
2. Inferior Rectus- rotates eye
down and toward midline.
3. Medial Rectus- rotates eye
towards midline.
4. Lateral Rectus- rotates eye
away from midline.
5. Superior Oblique- rotates eye
downward and away from
midline.
6. Inferior Oblique- rotates eye
upward and away from midline.
Chambers of the Eye
1. Anterior- behind cornea
2. Posterior- behind iris, in front of lens
a.
filled with aqueous humor and works in balance with
anterior chamber to keep eye shape
3. Vitreous- fills up the space behind the iris
a. filled with amorphous/ gelatinous fluid to help keep
eye shape.
chambers of the eye cont.
How we interpret sight
● Refraction- it’s an error when
you don’t 20/20 vision.
The error behind this is
that the light is not bending
properly when it passes
through the cornea and
retina of your eye
Cont.
cont.
● Convergent vs Divergent waveso
o
Structure: vertebrates
Convergence: axons originating from different parts
of the nervous system leading to the same neuron.
cont.
● allows the nervous system to collect, process,
and respond to information
● to focus: eyes adduct, the ciliary muscles
contract, and the pupils become smaller
cont.
● Divergence: impulses leaving
a neuron of a neuronal pool
and then by reaching several
other neuron
o Ex. one neuron may
o stimulate several others,
and so forth.
● can amplify an impulse- spreads it to increase
number of neuron within the pool
cont.
● Cones vs. Rods (both are photoreceptors)
Cones
 6 to 7 million cones provide eye’s color sensitivity
 more concentrated on yellow spot (Macula)
o Rods
 are numerous, about 120 million rods
 more sensitive than the cones
 exception not sensitive to color
o
Cont
● Dark vs Light vision● The “Dark” vision( scotopic vision): the rods
are responsible for vision under very dim
levels of illumination. They provide the
capability for seeing colors and resolving
better detail ( 20/20 or better)
o
o
mainly uses rods during the night
pigment granules first line of defense against light
cont.
● The “Light” vision (photopic vision): the
cones function at higher illumination levels.
They provide the ability to discriminate only
between shade of black and white
o
mainly uses cones in the day
cont
● Stereoscopic vision- the single perception of
a slightly different image from each eye. It
simultaneously perceives distance, depth,
height, and width of objects. Such vision is
possible because the pupils are 2-9mm in
diameter.
o
Pupils- dilate in the dark(3-8 mm) and in the light
they constrict (2-4 mm).
Citation
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