Transcript 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
●
●
●
●
●
●
"The Accessory Organs of the Eye - Human Anatomy." The Accessory
Organs of the Eye - Human Anatomy. N.p., n.d. Web. 06 May 2015.
"The Basics Of Eye Exercises. What Does It Aims To
Train?"ImproveEyesightHQ.com. N.p., n.d. Web. 06 May 2015.
Miller, Robert E., II. "The Eye and Night Vision." The Eye and Night Vision.
N.p., n.d. Web. 06 May 2015.
Segre, Liz. "The Science Behind the Look of Love." All About Vision. N.p.,
n.d. Web. 06 May 2015.
Strauss, Olaf. "The Eye and Night Vision." The Eye and Night Vision. N.p.,
n.d. Web. 06 May 2015.
"Visual Receptors." - RightDiagnosis.com. N.p., n.d. Web. 06 May 2015.