8 Special Senses.docx 2

8 Special Senses.docx 2 - Special Senses I Vision a...

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Special Senses I. Vision a. Affected significantly as we age b. Eye has 3 layers: b.i. Sclera - outermost b.i.1. Very front part is the white of your eye ( cornea ) b.i.1.a. Tough structure/layer of eye b.ii. Choroid coat - middle b.ii.1. Very dark layer/tissue of eye b.ii.2. Major function is to make sure light does not scatter all over the place (inhibits scatter of light / focuses light) b.iii. Retinal layer - innermost b.iii.1. Photosensitive cells b.iii.2. Rods and cones are found b.iii.3. 120 million rods and 6 million cones per eye b.iii.3.a. Rods - night vision; more sensitive to light b.iii.3.b. Cones - color vision b.iii.3.b.i. 3 different kinds- combination will give us all the different views that we see (Tricomatic Theory) b.iii.3.b.i.1. Red b.iii.3.b.i.2. Blue b.iii.3.b.i.3. Green b.iii.4. Forms the optic nerve of the eye in the back portion, also blood vessels c. 2 chambers c.i. Anterior chamber - everything in front of the lens c.i.1. Lens - held in place by being attached to suspension ligaments. c.i.1.a. Attach to ciliary muscles of eye c.i.1.b. When relax, muscles compress c.i.1.c. Tension, muscles elongate c.i.1.d. Change shape of eye to accommodate different views (near/far) it is a reflex action c.i.2. Iris - in front of lens c.i.2.a. Melanin- pigment that determines eye color. More melanin, darker the eye color c.i.2.b. Control opening into lens (pupil) c.i.2.c. Dilate pupil, open iris more c.i.2.d. Protective reflex (shine bright light in eye, constrict opening c.i.3. Aqueous humor - half life of 45 minutes (high turnover) because there are no blood vessels found on the cornea of lens of eye c.i.3.a. Delivery oxygen, nutrients, and remove waste products c.i.3.b. Very similar to blood plasma c.i.3.c. Produced by cells and secreted by cells in ciliary muscles into anterior chamber c.i.3.d. Canal of Schlemm - drains anterior chamber c.i.3.e. Contains some proteins and enzymes that help act as a defense (there are no immune/defense cells in eye) allows for cornea and lens transplants because there are no immune cells going to this area c.ii. Posterior chamber - everything in back of the lens c.ii.1. Vitreous Humor
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c.ii.2. Very slow turnover rate c.ii.3. Jelly like substance (less fluid) c.ii.4. Functions c.ii.4.a. Give support to retina (major function) c.ii.5. As light enters eye, enters cornea, get bent by lens, and focuses on retina. There is a spot on the retina called the Fovea Centralis (central focusing point) part of macular region of eye. Light focus on the fovea centralis. At the center of this fovea centralis, it is mostly cones, and as you move away from the center there are more cones. c.ii.5.a.
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This note was uploaded on 02/25/2012 for the course CHEM 1341 taught by Professor Compton during the Fall '08 term at Texas State.

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8 Special Senses.docx 2 - Special Senses I Vision a...

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