Structure of the Eye Outer Tunic (pg. 470) 1. Cornea 2. Sclera Middle Tunic (pg ) 3. Choroid Coat 4. Ciliary Body 5. Lens & Accommodation 6. Aqueous Humor 7. Iris 8. Pupil Inner Tunic (pg. 474) 9. Retina & Optic Disc 10. Posterior Cavity Function Illustration Location Identifying Features/Other info

Sponge: Set up Cornell Notes on pg. 69 Topic: 12.6: Structure of the Eye Essential Questions: 1.How does the shape of the lens change during accommodation? 2.1 Atoms, Ions, and Molecules 12.6: Structure of the Eye

Pg. 68 Human Body: Pushing the Limits: Sight Take at least 15 bullet points

Directions: You will need 12 colors for your table As we go through each part of the notes, please color-code and label the “diagram of the eye” AND your Brace Map notes Also, add any missing info.

5 Structure of the Eye Hollow Spherical (2.5 cm diameter) Wall has 3 layers outer fibrous tunic middle vascular tunic inner nervous tunic Pg. 69

6 Outer Fibrous Tunic Cornea Anterior 1/6 of outer eye “Window of the eye” Focuses incoming light rays Transparent No blood vessels Well supplied with nerves Many pain receptors

7

8 Sclera Posterior 5/6 of outer eye White portion of eye Protects the eye Attachment for extrinsic muscles Optic nerve pierces the sclera in the back Outer Tunic

9

10 Middle Tunic Choroid coat Many blood vessels provides blood supply Many melanocytes pigments absorb extra light Keeps inside of eye dark

11 Choroid Coat

12 Middle Tunic Ciliary body Anterior portion of middle tunic Holds lens in position Moves lens Secretes aqueous humor into the posterior chamber

13 Middle Tunic Lens Lies behind iris and pupil Elastic Under constant tension Puts near/far objects into focus As we age, lens becomes larger and less elastic which leads to vision impairment Accommodation: Suspensory ligaments Ciliary ligaments Close viewing relaxed contracted Far Viewing contracted relaxed

Figure Accommodation changing of lens shape to view objects

15 Ciliary Body

16 Aqueous humor (a-quee-us): fluid that circulates through the pupil and into the anterior chamber of the eye Provides nutrients Maintains the shape of the front of eye Removes waste If drainage is blocked—leads to glaucoma which can result in blindness

17 Middle Tunic Iris Colored portion of eye Lies between cornea and lens Smooth muscles control the size of the pupils Pupils Controls light intensity Constricted: less light in Dilated: more light in

18 Iris Pupil

19 Inner Tunic Retina Contains visual receptors (photoreceptors) rods/cones Continuous with optic nerve macula lutea (mac-ula lu-tay-a) –spot in retina; absorbs extra light fovea (fo-vea) centralis – center of macula lutea; region of retina that produces the sharpest vision; has largest concentration of cone cells optic disc – Blind spot; contains no visual receptors Nerve fibers leave here and become part of the optic nerve

20 Retina Optic Nerve Optic Disc

21 Inner Tunic Posterior Cavity largest compartment in eye contains vitreous (vi-tree-us) humor – jelly-like substance that holds retina flat against choroid coat maintaining pressure Helps transmit light to retina

22 Posterior Cavity

23 Extrinsic Eye Muscles

24 Video Notes: Split pg. 69 into four sections Outer fibrous tunic Middle vascular tunic Inner nervous (sensory) tunic The Humors and the Lens 3-5 Bullets Each

25 Layers of the Eye