The EYE SLO (s): You should be able to identify the accessory and internal structures of the eye and explain their function. You should be able to explain how light stimulates the production of nerve impulses, and trace the visual pathways to their destination in the brain. Essential Question: How does our eye detect external stimuli?
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The EYE SLO (s): You should be able to identify the accessory and internal structures of the eye and explain their function. You should be able to explain.
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The EYE
SLO (s): You should be able to identify the accessory and
internal structures of the eye and explain their
function.
You should be able to explain how light stimulates the
production of nerve impulses, and trace the visual
pathways to their destination in the brain.
Essential Question:
How does our eye detect external stimuli?
The EYE
Do Now:
List the parts of the eye that you are familiar with.
The EYE
Anticipatory Set:
Close your eyes and listen….Tell me what you hear. Is sound accentuated? Do you seem to hear more background noise when your eyes are closed? Is it completely dark when you close your eyes? Do you see flashes of light?
The EYE
Vocabulary: palpebrae
tarsal glands
conjunctiva
lacrimal glands
lacrimal punctae
lacrimal canals
lacrimal sac
lacrimal lake
nasolacrimal duct
corneairisciliary bodyaqueous humorvitreous humor
sclera
cornea
limbus
choroid
retina
rods
cones
External Features of the Eye
Palpebrae (eyelids)- separated by the palpebral fissue (intersection of top and bottom lids)
Tarsal glands-Supplies oil substance to eye that prevents tear spillage onto the cheek, trapping tears between the oiled edge and the eyeball, and makes the closed lids airtight
External Features of the Eye
Conjunctiva- lines the inside of the eyelids and covers the sclera (white part of the eye)- covers most of eye except cornea Sclera-white of the eye
Limbus-border of cornea and sclera
Cornea is transparent anterior portion
Lacrimal apparatus- system containing the structures for tear production and drainage.
• lacrimal gland-form/secretes the tears
• lacrimal gland ducts-convey
the fluid to the surface of the eye
• Tears collect in the lacrimal lake
• lacrimal punctum-collect tears
produced, convey fluid through the
lacrimal canals to the lacrimal sac
• nasolacrimal duct-convey fluid into
the cavity of the inner nose
• carotid plexus -the nerve
supply of the lacrimal apparatus
Accessory structures of the eye
Lacrimal sac
The Anatomy of the Eye
The EYE
DO NOW:Why do people cry? Is there a purpose/function of “emotional crying?” Using your laptops, briefly research any current theories on crying.
The EYE
SLO (s): You should be able to identify the accessory and
internal structures of the eye and explain their
function.
You should be able to explain how light stimulates the
production of nerve impulses, and trace the visual
pathways to their destination in the brain.
Essential Question:
How does our eye detect external stimuli?
The EYE
Vocabulary: palpebrae
tarsal glands
conjunctiva
lacrimal glands
lacrimal punctae
lacrimal canals
lacrimal sac
lacrimal lake
nasolacrimal duct
corneairisciliary bodyaqueous humorvitreous humor
sclera
cornea
limbus
choroid
retina
rods
cones
Anatomy of the eye-The Orbit
Orbit of the Eye
Anatomy of the Eye-Muscles
• Extrinsic / Extraocular Muscles
• Act to turn or rotate the eye
vertical horizontal torsion/twisting
Anterior and Posterior Cavities-Fluids of the Eye
Aqueous humor- transparent, gelatinous fluid similar to plasma, located in anterior cavity
Fluids in the eye
• Produced by ciliary body
•Circulates within the eye- continually replenished
•Purpose--Maintains the intraocular pressure/inflates the eye- Provides nutrition for the avascular ocular tissues (cornea, lens, and anterior vitreous)-Immune support
Fluids in the eye
Vitreous humor
• fills the posterior cavity
• tautly hold the eye’s shape and keeps the retina in place
• not recycled – permanent fluid
Fluids in the eye
Checking for Understanding.
List the 2 fluid filled chambers of theeye. What is their purpose?
The eye-internal structure
Three layers
• Outer fibrous tunic
• Sclera and
cornea
• Middle vascular tunic
• Iris, ciliary
body, choroid
• Inner nervous tunic
• Retina
Suspensory ligaments
Internal structures of the eye
Outer Fibrous Tunic-
Cornea- • transparent front part of the eye • lies anterior to the anterior
chamber, iris, pupil, and lens
• refracts light/helps focus incoming light (along with anterior chamber and lens)-
• primary and most powerful structure to focus light
Sclera- • Opaque, protective outer layer
of the eye • composed of tough, fibrous
tissue containing collagen (structural protein) and elastic fiber (bundles of proteins in connective tissue that can stretch up to 1.5 times their length, and snap back to their original length when relaxed)
• site of attachment for the extrinsic eye muscles which rotate the eyeball.
Internal structures of the eye
Iris- • responsible for
controlling the diameter and size of the pupil/amount of light reaching the retina
• "eye color.“
Ciliary Body-
Choroid-
Middle Vascular (Blood Vessels) Tunic
The Pupillary Muscles
Controls diameter of pupil in response to the intensity of light that falls on the retina
Internal structures of the eye
Iris-
Ciliary body-• attach to
suspensory ligaments of lens
• Ciliary muscles change the shape of the lens for accommodation
• Ciliary processes produce aqueous humor
Choroid-
Middle Vascular (Blood Vessels) Tunic
• Posterior to the cornea
• Lens helps focus images
• Accommodation is the process by which the lens adjusts to focus images
• Light is refracted as it passes through lens
• Normal visual acuity is 20/20
Lens
Internal structures of the eye
Iris-
Ciliary Body-
Choroid-
• network of blood vessels that provides oxygen and nourishment to the outer layers of the retina
• lies between the retina and the sclera
• absorbs excessive light
Middle Vascular (Blood Vessels) Tunic
Internal Structures of the Eye: Retina
Inner Nervous Tunic
-- Retina-• Outer pigmented portion• Inner neural part contains rods and cones(photoreceptors)• optic nerve –located the center of the retina
-from the center of the optic nerve radiates the major blood vessels of the retina
Internal Structures of the Eye: Retina
- Cones –more concentrated at the macula
--densely packed at the center of the macula called the fovea
-- Color reception
-- Less sensitive to light
-- High resolution vision/visual acuity
The Organization of the Retina
• Rods –more numerous (120 million)
• More sensitive than the cones
• Dark-adapted vision/motion sensors
Physiology-PhotoreceptionRetinal Pathway
• Photoreceptorsconvert light to
signals that stimulate a
changein the cells membrane potential
• Signals eventually travel down ganglion cells, to the brain via the optic nerve• axons of the ganglion
cells form the optic nerve and exit the eye to the brain
Figure 17.19
Checking for Understanding
• What is the significance of rods and cones?
• If you were driving at night, which are responsible for your visual acuity?
• Which allows you to see color?
• Follow the path of light from the external environment to the retina. List the structures that the light passes through sequentially.