1. The Special Senses Vision (sight) Gustation (taste) Olfaction (smell) Hearing Equilibrium (balance) Chapter 17

2. Accessory Structures of the Eye Eyebrows divert sweat and contribute to facial expressions Eyelids (palpebrae) blink to protect the eye and lubricate their surface Eyelashes detect and deter foreign objects

3. Accessory Structures of the Eye Cont. Conjunctiva - a mucous membrane lining the inside of the eyelids and the anterior surface of the eyes Conjunctivitis (“pinkeye”) - inflammation of conjunctiva

4. Accessory Structures of the Eye Cont. Lacrimal Apparatus: –Lacrimal gland –Lacrimal sac –Nasolacrimal duct Keeps conjunctival surfaces moist and clean

5. Eye Muscles Lateral, medial, superior, and inferior rectus muscles; superior and inferior oblique muscles

6. Internal Anatomy of the Eye Aqueous humor - clear, watery fluid in the anterior chamber Cornea - transparent tissue covering the front of the eye; bends light Pupil - hole in the center where light passes through Iris - controls the size of the pupil; gives "color" to the eye Lens - transparent tissue that bends light passing through the eye Retina - on the back of the eye, contains photoreceptors (center of retina = fovea)

7. Internal Anatomy of the Eye Rods - photoreceptors responsive in low light conditions Cones - photoreceptors responsive to color and in bright conditions Sclera – the “white” of the eyeball Choroid – membrane between sclera & retina Vitreous Humor - clear, jelly-like fluid found in the back portion of the eye, maintains shape

8. www.uniteforsight.org/course/eyea natomy.php http://www.youtu be.com/watch?v= gvozcv8pS3c

9. Visual Disorders Myopia (nearsightedness) – objects far away appear blurry; can be corrected with concave lenses (- diopter) Hyperopia (farsightedness) – close objects appear blurry; can be corrected with convex lenses (+ diopter)

10. Visual Disorders Cont. Astigmatism - uneven curvature in cornea causes out of focus image Cataract - clouding of the lens, scatters the light rays

11. Visual Disorders Cont. Glaucoma - caused by a build-up of aqueous humor; the excessive amount of fluid causes pressure against the retina, affecting vision; if untreated, will result in permanent blindness Presbyopia - form of hyperopia due to weakening of eye muscles; normal part of aging