Sponge: Set up Cornell Notes on pg. 69 Topic: 12.6: Accessory Organs of the Eye Essential Questions: What is the function of the lacrimal apparatus? Describe the pathways of the tears. 2.1 Atoms, Ions, and Molecules 12.6: Accessory Organs of the Eye What is the function of the lacrimal apparatus? Describe the pathways of the tears.

Vision: Crash Course A+P 8m28s P bullets

3 Visual Accessory Organs Eyelids Lacrimal apparatus Extrinsic eye muscles

4 Eyelid (palpebra) is composed of four layers: 1. Skin Thinnest skin of the body Protection 2. Muscle Orbicularis oculi (orbic-u-laris) – closes lid Levator palperbrae superioris – opens lid 3. Connective tissue Tarsal glands – secrete oil onto eyelashes Helps keep lids from sticking together

5 4. Conjunctiva (Con-junct-i-va) Mucous membrane; lines eyelid and covers portion of eyeball Lubricates eye Prevents microbes from entering the eye Protection Contain an enzyme that has antibacterial properties Reduces eye infections Thin/Freely movable/ transparent

6 Conjunctivitis aka “Pinkeye”: inflammation of the conjunctiva

7 Causes: Viruses Bacteria Irritants such as shampoos, dirt, smoke, and pool chlorine Allergies, like dust, pollen, or a special type of allergy that affects some contact lens wearers Pinkeye in newborn babies, however, should be reported to a doctor immediately, as it could be a vision-threatening infection.

8 Symptoms: The symptoms of pinkeye differ based on the cause of the inflammation, but may include: Redness in the white of the eye or inner eyelid Increased amount of tears Thick yellow discharge that crusts over the eyelashes, especially after sleep Green or white discharge from the eye Itchy eyes Burning eyes Blurred vision Increased sensitivity to light

9 Treatment: The treatment for pinkeye depends on the cause: Bacteria: Antibiotics, in the form of eye drops, ointments, or pills. Viruses: Must run its course (4-7 days) Irritants: For pinkeye caused by an irritating substance, use water to wash the substance from the eye for five minutes. Allergies: Allergy-associated conjunctivitis should improve once the allergy is treated and the allergen removed.

10 Complications: Certain forms of conjunctivitis can become serious and sight- threatening, because they can cause cornea scarring. Caused by gonorrhea, chlamydia, or certain strains of the adeno virus.

11 Lacrimal Apparatus Lacrimal gland Lateral to eye Secretes tears 1. Canaliculi (cana-lik-u-lie) Collects tears 2. Lacrimal sac Collects tears from canaliculi 3. Nasolacrimal duct Collects tears from lacrimal sac and empties tears into nasal cavity

How does this picture explain why your nose start to run when you are crying?

13 Tear glands secrete excessively when a person is upset or when the conjunctiva is irritated Tears spill over the eyelid, nose fills with fluid

The Eyes Natural Protection 2m6s 14 P bullets

Accessory Structures of the Eye Start: 2m36s 15 P bullets

Figure Extrinsic Eye Muscles

17 Superior rectus Rotates eye up and medially Inferior rectus Rotates eye down and medially Medial rectus Rotates eye medially Extrinsic Eye Muscles

18 Lateral rectus Rotates eye laterally Superior oblique Rotates eye down and laterally Inferior oblique Rotates eye up and laterally Extrinsic Eye Muscles

19 SR= superior rectus IR= Inferior rectus MR= Medial rectus LR= lateral rectus SO= Superior oblique IO=Inferior oblique

20 The motor units of the eye muscles have the fewest muscle fibers of any muscles in the body Move with great precision Eyes move together Align when looking at something

Last Call for Lab Report 33 21

Pass back and Taping time 40: 5 types of receptors 42: Lab 30 44: Clinical Application : Olfactory nerve pathway 48: 12.3 Clinical App 50-51: Lab Report 31 53: External Ear 54: Middle ear bones 56: Middle ear 58: Cross section of cochlea 60: Ear Quiz 61: How sound travels through inner ear 62: Clinical application : Lab 32 Ear and Hearing 63: Conductive v. sensorineural hearing loss 64: Lab Report 33