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April 26, 2011: TuesdayToday’s Agenda

New Seating Chart

A. Journal Questions:

1. Where does most nutrient absorption occur within your digestive system?

2. What is peristalsis?

*B. Lecture II: Eye Anatomy & Function.

Ending on Slide 26

C. Color Anatomical Structures of the Eye

D. Discovery Video: Sight & Sensation

E. Homework: Study for Next week’s exam:

Exam on Monday: Lobes of the brain, the eye, Digestion, Absorption, and Excretion.

Visual Disorders:A. Myopia = Nearsightedness:

(1) Individuals can only see things that are close to them.

-distant objects look blurry.

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The Function & Anatomy of the Eye

By Dr. Rick Woodward

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Eye Charts

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Anatomy Terminology

A. Anterior = Front

B. Posterior = Back

C. Ventral = Belly

D. Dorsal = Top

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The Eyeball is Composed of 3 Layers:

1. Fibrous Tunic (Connective tissue)

2. Vascular Tunic (Receives blood)

3. Nervous Tunic (Retina: Receives impulses from the nervous system)

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The Eyeball is Composed of 3 Layers:1. Fibrous Tunic: The outer

coat of the eyeball.

(1) Cornea

(2) Sclera

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The Eyeball is Composed of 3 Layers:

(1) Cornea: Anterior portion of the fibrous tunic

a. Nonvascular, transparent coat which covers the pigmented iris.

b. Function: Helps focus light.

(Most important refracting surface of the eye.)

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The Eyeball is Composed of 3 Layers:(2) Sclera: Posterior portion of the

fibrous tunic.

a. Also called the “white” of the eye.

b. Function: Gives shape to the eye.

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The Eyeball is Composed of 3 Layers

2. Vascular Tunic – The middle layer of the eyeball.

(1) Choroid: Posterior portion of the vascular tunic.

a. Provides blood supply and absorbs light rays.

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The Eyeball is Composed of 3 Layers(2) Ciliary Body: Anterior portion

of the vascular tunic.a. Composed of two structures:

(1) Ciliary Process (folds of ciliary body): Secretes aqueous humor.(2) Ciliary Muscle:

Smooth muscle that alters the shape of the lens.

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The Eyeball is Composed of 3 Layers(3) Iris: Anterior portion of the vascular

tunic.

a. Pigmented doughnut-shaped structure composed of muscle fibers.

b. Function: Regulates the amount of light that enters the eye.

c. Pupil: Black hole in the center of the iris through which light enters the eyeball.

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The Eyeball is Composed of 3 Layers

3. Nervous Tunic (Retina) –The inner coat of the eyeball.

a. Found only in the posterior portion of the eyeball.

b. Function: Image formation.

(1) Receives light and converts light into nerve impulses, it then transmits the information to the optic nerve and then to the occipital lobe of the brain

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The 2 Layers of the Retina:1. Outer pigmented layer

(non-visual portion)

2. Inner nervous tissue layer (visual portion)

a. Contains Photoreceptors:

(1) Rods

(2) Cones

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Function of the Rods:

A. Specialized for vision and dim light.

B. Discrimination between different shades of dark and light.

C. Allows us to see shapes and movement.

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Function of the Cones:A. Color vision and visual

acuity (sharpness of vision)

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The LensA. Located behind (posterior) the

pupil and iris.

B. The lens is avascular and normally transparent

“Cataract = loss of transparency”

C. Suspensory Ligaments hold the lens in position

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The LensD. Function: Focus light

rays for clear vision.

E. Contact lenses work by conforming to the curvature of the cornea.

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The Interior of the EyeballA. Composed of two cavities:

(1) Anterior Cavity (located anterior to the lens)

a. Anterior Chamber

b. Posterior Chamber

(2) Posterior Cavity (located between the lens and the retina)

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Anterior ChamberA. Located in front (anterior) of

the iris and behind the cornea.(1) Filled with aqueous humor(2) Pressure is kept within normal limits by drainage of aqueous humor through the Canal of Schlemn.-Glaucoma is characterized by an increase in intraocular pressure.

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Posterior CavityA. Located between

the lens and the retina.

B. It is a much larger cavity.

C. It contains vitreous humor; which helps prevent the eyeball from collapsing.

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Start to Study for Your ExamIt will cover: Eye, Digestion,

Absorption, Excretion,

Use your lecture notes, handouts, Film: Your Exam is next Monday

Sheep Eye Dissection Coming up Next!