Presentation on theme: "Nose, Eyes, Ear, and Tongue"— Presentation transcript:
1Nose, Eyes, Ear, and Tongue Ch 12: Special SensesNose, Eyes, Ear, and Tongue
2External Anatomy of the Eye Eyelids: Protection, LubricationEyelashes: ProtectionGlands: Meibomian and CiliaryMeibomian: Oil glands, modified sebaceous glands on eyelidsCiliary: Modified sweat glands.
3Third eye-lidGathers dustand produceseye crispies.In other animalsIt can cover theEye.
4What is the Lacrimal apparatus and what does it do? Lacrimal apparatus. Fig 12.5Lacrimal glands: release tearsLacrimal ducts (eyelid) and canals (nose)Nasolacrimal ducts: empties into the noseLacrimal Secretion: Tears have antibodies and lysozyme. Cleans, moistens.Why is it called a healthy cry?Lysozyme
5What are the Muscles of the eye and how do they move it? Lateral rectus: Moves eye laterallyMedial rectus: Moves eye mediallySuperior rectus: Moves eye upInferior rectus: Moves eye downS & I ObliquesFig 8.15, 197Fig 12.7, pg 296Practice usingThe Eye Muscles
6What are the internal structures of the eye? Pg. 295, Fig 12.6 Sclera: white of the eyeCornea: ClearIris: colorful part of the eyePupil: Opening of the IrisLens and ciliary body: Ciliary body holds the lens in place. The lens focuses light on the back of the eye.
7What fills the inner eye? Pg 298 Aqueous Humor: Circulates from the cornea to the Lens through the canal of Schlemm.Vitreous Humor: In the space behind the lens. Keeps the eyes shape, and keeps intraocular pressure stable.Floaters?Glaucoma?
9What lines the back of the eye? Retina: photoreceptor layerRods: Black and whiteCones: ColorChoroid coat: Dark, vascularized layer. Absorbs light. *Non-humans are differentSclera: Thick, white covering
11How do you see? Pg. 299.How we SeeDetails of VisionAdam
12Light travels through the… Cornea to the Aqueous humor to the Pupil to the lens.In the Lens light is bent so that it will hit the Retina of the eye.To get to the Fovea Centrals light must continue to pass through Vitreous humor.Light then hits the Retina where Rods and Cones interpret the image and sends it to the Optic nerve to the brain.
13Where is your vision the best and the worst? Worst vision: The blind spot. To find your blind spot go to pg 297 in the book.Blind spot is where the optic nerve takes the image to your brain. There are no rods or cones here. Your brain just fills in the gaps.Best vision: Fovea Centralis. Lateral to the blind spot, only contains cones. This is the spot of greatest visual acuity.
15Why do cones see better than rods? See Fig 12.8Many Rods, one nerve = blurred edges.One Cone, one nerve = crisp lines.Which do you think causes Night Blindness?What type of cones do you have:Blue cones: see blue lightGreen cones: see green lightRed cones: see red and green light.
16Component colors are detected by cone cells in the retina Component colors are detected by cone cells in the retina. All colors in the visible spectrum can be represented as a combination of red, green, and blue. In the retina, a full-color image is broken up into component colors by cone cells specialized to detect red light (long wavelength), green light (med. wavelength), blue light (short wavelength).
17What is colorblindness? The lack of a type of cone, or all cones.Sex-linked gene.Men suffer from color blindness more often than females.Vision of theColorblind
18How is Lasik’s performed? StepstoLASIKSurgeryStepstoLASIKSurgery
22External EarHow theEar hears.AuricleExternal Auditory Meatus-2.5 cm long leads to Middle ear
23The Middle Ear Tympanic Cavity: air-filled space Tympanic Membrane- ear drumPressure changes cause it to vibrate, enhances the sound waveAuditory Ossicles: smallest bones in the body. Malleus, incus, and stapes.The Stapes vibrate at the oval window causing fluid in the inner ear to move, stimulating hearing receptors.
28Auditory tube mucous membranes connect directly with the middle ear linings. Thus, mucous membrane infections of the throat may spread through these tubes and cause a middle ear infection.Question: Why is it important to keep a babies head up when bottle feeding?How theTubes workXylitol gum and chewing it could help prevent ear infections.
29Inner Ear. Pg. 304 Cochlea: hearing Oval Window: the stapes vibrates this in order for your nerves to fire and for you to hear sound.Quick ReviewSound on CochleaReview of the Ear:In depth on CochleaAnd Hearing
30Inner Ear: pg. 306 - 307 Semicircular Canals: maintain equilibrium The vestibular system
32The Nose. Fig 12.3 Smells using Olfactory Receptors Sex andSmellSmells using Olfactory ReceptorsYellow-brown mass located at the top of each nasal cavitySize of a postage stamp.Factoid:These swirl theAir so thatDust and germsStick to theMucus.How we smell
33How do olfactory receptor cells smell? Use Olfactory HairsMust be covered in mucusChemicals dissolve in mucusTrigger nerveOlfactory NerveConnects to the Olfactory Bulb in Brain. Travels to temporal lobe for interpretation.Tied to the limbic system (emotional system) of the brain. Smells stimulate memories.
34Interesting Nose facts Olfactory neurons that are over stimulated shut off. (Can’t smell X after a while.)Anosmias: loss of smell due to head injuries, nasal cavity inflammation (cold, allergy, smoking) or age.Often caused by a zinc deficiencyOlfactory auras: epileptics may have smell hallucinations before a seizure.Because dust in space does not settle Austronoauts sneeze about 100 times a day!
35The Tongue. Fig. 12.4 . Factoid: You can detect and distinguish between 10,000odors, butonly 5 tastes..
37How Do You Taste?Gustatory cells- respond to chemicals that are dissolved in salivaTaste buds- receptor sites for tastes. Most are on the tongue. Some are on the roof of the mouth and cheeksPapillae- on the sides of this structure is where taste buds are foundHow do youTaste?
38Basic Taste Sensations Sweet- sugar, OH- groupsSour- acidic, H+Umami- meaty or savoryBitter- alkaloid bases, very few H+ bondsSalty- metal ionsThe scienceOfPicky Eaters