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
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 12.29 Accommodation changing of lens shape to view objects
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
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
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