Chapter 17 The Special Senses

1. Chapter 17 The Special Senses

2. Olfaction - Olfactory Organs • Location: nasal cavity on either side of nasal septum • 2 layers: • 1. Olfactory epithelium • Olfactory receptors • Supportive cells • Basal cells • 2. Lamina propria • Areolar tissue • BVs • Nerves • Olfactory glands • (AKA Bowman’s) • secretions + water = mucus

3. Figure 17-1a The Olfactory Organs Olfactory Pathway to the Cerebrum Olfactoryepithelium Olfactorynerve Olfactorytract Centralnervoussystem Olfactorybulb • Distinguish among 2000-4000 chemical stimuli • 50 primary smells • Smell interpreted based on pattern of receptor activity • High turnover (basal cells) • Receptors with age Cribriformplate Superiornasalconcha The olfactory organ onthe left side of the nasal septum

4. Olfactory Pathways • Odorant binds to receptor proteins on Cilia • ATP converted to cAMP • Na+ channels open and AP generated • AP moves to olfactory nerve fibers olfactory bulb olfactory tract  olfactory cortex, hypothalamus, limbic system Why smell can trigger memory or emotions

5. Figure 17-3a Gustatory Receptors Water receptors(pharynx) Gustation Umami • Sweet • Sour • Salty • Bitter • Umami: taste due to glutamates in food (broth/stock, Parmesan cheese, anchovies) • Water receptors: sensory info from water receptors processed by hypothalamus = ADH secretion • Olfactory fully functioning = sensitivity to tastes Sour Bitter Salty Sweet Landmarks andreceptors on thetongue

6. Taste Buds • Lingual papillae: epithelial projections on tongue 1000’s of taste buds 5 taste buds 0 taste buds, friction • Taste buds = taste receptors + specialized epithelial cells

7. Accessory Structures 1. Eyelids- shade during sleep, protect, spread lubricant 2. Eyelashes & Eyebrows- protection from sun, foreign objects Sebaceous ciliary glands- base of eyelash, release lubricant Infection of = sty 3. Conjunctiva- protective mucous over sclera 4. Lacrimal glands- produces tears

8. Vision & the Eyeball 1. Cornea- covers the eye, protection 2. Sclera- "white", covers all except cornea, gives shape 3. Choroid- posterior blood vessels, absorbs stray rays to prevent scattering 4. Ciliary body- anterior choroid Ciliarymuscle-controls shape of lens 5. Iris- colored part, melanin, regulates pupil 6. Pupil- black hole in center of iris

9. 7. Retina- lines posterior ¾ contain Retinal (Vit A)-light absorber photoreceptors: Rods- 120 mill., dim light, contain rhodopsin (photopigment) Cones- 6 mill., color vision (blue, green, red-3 photopigments) Fovea centralis- area of retina that contains only cones, sharpest vision Optic disc/Blind spot-where optic nerve leaves, no rods/cones 8. Lens- focuses images, held in place by suspensory ligaments The human lens is transparent due to the replacement of organelles with clear proteins known as crystallins 9. Anterior chamber (front of iris) & Posterior chamber (behind) contain aqueous humor- watery nourisher 10. Vitreous chamber- behind lens, jelly that holds retina in place

10. To form clear images 1. refraction (bending) of light by the lens and cornea, images are inverted(upside down) 2. accommodation by lens shape -wider for closer objects, thinner for distant 3. constriction of pupil

11. Figure 17-19 Convergence and Ganglion Cell Function Retinal surface(contacts pigment epithelium) • Visual Pathway • Photoreceptors stimulated • 2. Information passes to bipolar cells then ganglion cell (great convergence) • M cells monitor rods and provide info about: general form, motion, shadows in dim light • P cells monitor cones and provide information about: edges, fine detail and color Receptive fieldof ganglion cell Receptive field Photoreceptors Bipolar cell Amacrinecell Ganglion cell

12. Figure 17-20 The Visual Pathways Visual Field Combined Left side Right side 3. Axons of all ganglia converge on optic disc optic nerve 4. ½ info goes to R other ½ goes to L 5. Information received by many areas including brain stem and visual cortex 6. Information compiled by visual association area Left eye Right eye only Binocular vision only The Visual Pathway Photoreceptorsin retina Optic disc Optic nerve(N II) Optic chiasm Optic tract Diencephalonandbrain stem Visual cortexof cerebralhemispheres Left cerebralhemisphere Right cerebralhemisphere

13. Abnormalities • Cataracts- cloudy lens • Glaucoma- most common cause of blindness, abnormally high intraocular pressure, buildup of aqueous humor Cataracts

14. Myopia (nearsighted)- hits in front of retina • Hyperopia (farsighted)- hits in back of retina • Astigmatism- either the cornea or lens has curvature Lasik Eye Surgery: https://www.youtube.com/watch?v=TBfAuvOPjeg

15. Color Vision • Integration of information from red, green, and blue cones (all three stimulated = white) • Color blindness-missing cones How we see color: http://www.youtube.com/watch?v=l8_fZPHasdo This is not yellow: http://www.youtube.com/watch?v=R3unPcJDbCc&NR=1&feature=endscreen Colorblindness Test: Start this at 2:00 http://www.youtube.com/watch?v=yEIM4jmK1F0

16. Vision and Pigments • Pigment = light absorbing molecule • Pigments of Rods • Rhodopsin (with protein opsin) • Retinal = synthesized from vitamin A • Pigments of Cones • Retinal • Other forms of opsin • Type of opsin stimulated = absorption of specific wavelength of light = color vision

17. Why should you eat Carrots to have good eyes? • Carrots do not contain Vitamin A- Instead they contain CAROTENE, an orange pigment, which is converted to retinol (Vit A) in the body. • Retinal, the pigment in the rhodopsin molecule, is synthesized from Vit A • Lack of Vit A can cause night blindness and even permanent blindness!

18. The Ear • External • Auricle- helix (upper) & lobule • External Auditory Canal/Meatus • Cerumen-wax & hair for protection • Eardrum/Tympanic membrane • -has a covering that can be damaged

19. B. Middle Ear- air-filled cavity • Auditory Ossicles- 3 smallest bones in body • 1. Malleus-hammer • 2. Incus- anvil • 3. Stapes- stirrup • Fits into oval window • Below is round window • Eustachian tube/Auditory tube- connects ear to nasopharynx • Equalizes pressure • Normally closed, but opens with yawning and swallowing

20. C. Inner Ear/ Labyrinth • Bony labyrinth- outer, contains perilymph Membranous labryinth-endolymph • 1. Semicircular canals- each has a swollen area (ampulla) • 2. Vestibule- membranous utricle & saccule • 3. Cochlea- “snail” • Scalavestibuli, scala tympani, organ of corti- 16,000 hair cells to hear

21. Figure 17-21 The Anatomy of the Ear (movement of endolymph) Middle Ear Internal Ear External Ear Auditory ossicles sense of rotation Ovalwindow Semicircular canals Auricle Facial nerve (N VII) Vestibulocochlearnerve (N VIII) sense of sound Bony labyrinthof internal ear Cochlea Auditory tube Tonasopharynx Tympanicmembrane Vestibule External acousticmeatus Roundwindow sense of gravity/acceleration (saccule and utricle)

22. Auditory Pathway

23. Figure 17-24b The Semicircular Ducts The Ear and Equilibrium Movement of endolymph stimulates/inhibits hair cells • Hair cells monitored by sensory neurons in vestibular ganglia • AP propagates to Vestibulocochlear nerve • Information relayed to cerebellum • Static- maintenance of the position of the body relative to gravity • Dynamic- maintenance of body position in response to sudden movements (Rotation, acceleration, deceleration)

24. Sound waves- high & low pressure traveling in the same direction • Frequency = # of vibrations • ↑ Pitch = ↑ Frequency • Increase in Intensity (size or amplitude) = louder • Measured in decibels

25. Hearing and Age • Young children have greatest hearing range • Injuries to ear accumulate with age • Tympanic membrane loses flexibility • Articulations between ossicles stiffen • Round windows ossify