Bellwork & Objective

1. Bellwork & Objective • Put the following structures in order of the path of sound: • Cochlea, eardrum, pinna, ossicles, auditory canal, cochlear nerve • Pinna, Auditory canal, Eardrum, Ossicles, Cochlea, Cochlear nerve • SWBAT explain how our equilibrium works. • SWBAT explain how the senses of smell and taste work.

2. Special Senses Equilibrium, Smell, Taste

3. Organs of Equilibrium • Receptor cells are in two structures • Vestibule • Semicircular canals

4. Organs of Equilibrium • Equilibrium has two functional parts • Static equilibrium – sense of gravity at rest (which way is up?) • Dynamic equilibrium – movement (spinning, being on a boat)

5. Static Equilibrium - Rest • Maculae – receptors in the vestibule • Report on the position of the head • Send information via the vestibular nerve • Anatomy of the maculae • Hair cells are embedded in the otolithic membrane • Otoliths (tiny stones) float in a gel around the hair cells • Movements cause otoliths to bend the hair cells

6. Function of Maculae

7. Dynamic Equilibrium - Movement • Crista ampullaris – receptors in the semicircular canals • Tuft of hair cells • Cupula (gelatinous cap) covers the hair cells

8. Dynamic Equilibrium • Action of head movements • The cupula stimulates the hair cells • An impulse is sent via the vestibular nerve into the cerebellum

9. Chemical Senses – Taste and Smell • Both use chemoreceptors • Stimulated by chemicals in solution • Taste has four types of receptors • Smell can differentiate a large range of chemicals • Both senses complement each other and respond to many of the same stimuli

10. Olfaction – Sense of Smell • Olfactory receptors are in the roof of the nasal cavity • Neurons with long cilia (olfactory hairs) • Chemicals must be dissolved in mucus for detection • Impulses are transmitted via the olfactory nerve

11. Sense of Taste • Taste buds house the receptor organs • Location of taste buds • Most are on tongue • Soft palate • Cheeks

12. The Tongue and Taste • The tongue is covered with projections called papillae • Filiform papillae – sharp with no taste buds • Fungiform papillae – rounded with taste buds • Circumvallate papillae – large papillae with tastebuds • Taste buds are found on the sides of papillae

13. Stucture of Taste Buds • Gustatory cells are the receptors • Have gustatory hairs • Stimulated by chemicals dissolved in saliva

14. Stucture of Taste Buds • Impulses are carried to the gustatory complex by several cranial nerves

15. Exit Ticket • Pick one special sense you would not want to lose (sight, equilibrium, hearing, smell, taste) and briefly describe how it works. Why would you not want to live without this sense?