AP 206 Special Senses - Ear and chemical senses .pptx
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Special Senses AP206 Chapter 8 The Senses Special senses 1. Sight 2. Hearing 3. Equilibrium 4. Smell 5. Taste © 2015 Pearson Education, Limited. The Ear External (outer) ear Midd...
Special Senses AP206 Chapter 8 The Senses Special senses 1. Sight 2. Hearing 3. Equilibrium 4. Smell 5. Taste © 2015 Pearson Education, Limited. The Ear External (outer) ear Middle ear Internal (inner) ear Houses two senses: 1. Hearing Auricle Vestibulocochlear nerve (pinna) 2. Equilibrium (balance) Semicircular canals Oval window Receptors are mechanoreceptors Cochlea Vestibule The ear is divided into three areas: Round window 1. External (outer) ear Pharyngotympanic (auditory) tube 2. Middle ear (tympanic cavity) Tympanic membrane Hammer Anvil Stirrup 3. Inner ear (bony labyrinth) External acoustic (eardrum) (malleus) (incus) (stapes) meatus Auditory ossicles © 2015 Pearson Education, Limited. (auditory canal) The External Ear External (outer) ear Middle ear Internal (inner) ear Involved in hearing only Vestibulocochlear Auricle nerve Structures of the external ear (pinna) Semicircular Auricle (pinna) canals Oval window Cochlea External acoustic meatus (auditory canal) Vestibule Round window Narrow chamber in the temporal bone Lined with skin and ceruminous (wax) glands Pharyngotympanic (auditory) tube Ends at the tympanic membrane (eardrum) Tympanic membrane Hammer Anvil Stirrup (eardrum) (malleus) (incus) (stapes) External acoustic meatus Auditory ossicles (auditory canal) © 2015 Pearson Education, Limited. The Middle Ear (Tympanic Cavity) Air-filled cavity within the temporal bone External (outer) ear Middle ear Internal (inner) ear Involved only in the sense of hearing Located between tympanic membrane and oval Vestibulocochlear Auricle window and round window (pinna) nerve Semicircular Two tubes are associated with the middle ear: canals Oval window Cochlea 1. Opening from auditory canal covered by Vestibule eardrum Round window 2. The pharyngotympanic, or auditory, tube Pharyngotympanic (auditory) tube connects the middle ear with the throat Tympanic membrane Hammer Anvil Stirrup Allows for equalizing pressure during yawning External acoustic (eardrum) (malleus) (incus) (stapes) or swallowing meatus Auditory ossicles (auditory canal) This tube is otherwise collapsed Bones of the Middle Ear (Tympanic Middle ear Cavity) Three bones (ossicles) span the cavity: 1. Malleus (hammer) 2. Incus (anvil) 3. Stapes (stirrup) Function Vibrations from tympanic membrane move the hammer anvil stirrup oval window of inner ear Hammer Anvil Stirrup (malleus) (incus) (stapes) Auditory ossicles The Inner Ear or Bony Labyrinth External (outer) ear Middle ear Includes sense organs for hearing and Internal (inner) ear balance Filled with perilymph Vestibulocochlear nerve Extracellular fluid Semicircular canals Contains a maze of bony chambers within Oval window Cochlea the temporal bone: Vestibule Round window Cochlea Vestibule Semicircular canals Membranous labyrinth is suspended in perilymph and contains endolymph Other Organs of Hearing Spiral organ of Corti Located within the cochlear duct Hearing receptors/hair cells on the basilar membrane Gel-like tectorial membrane is capable of bending hair cells Cochlear nerve attached to hair cells transmits nerve impulses to auditory cortex on temporal lobe Mechanism of Hearing Sound waves enter the auditory canal and leads to the ear drum The eardrum vibrates from the sound waves and sends the vibrations to the three bones of the middle ear Tympanic membrane hammer anvil stirrup These three bones increases the sound vibrations The vibrations enters the inner ear via the oval window The vibrations reach the Spiral organ of Corti in the cochlea Vibrations from sound waves move tectorial membrane Hair cells are bent by the moving tectorial membrane This starts an action potential in the cochlear nerve Impulse travels to temporal lobe in the brain Figure 8.16 Route of sound waves through the ear. EXTERNAL EAR MIDDLE EAR INTERNAL EAR Auditory Ear- Hammer, Oval Fluids in cochlear canals Pinna canal drum anvil, stirrup window Upper and middle lower Pressure Spiral Time One Amplitude organ Amplification vibration in middle ear of Corti stimulated Organs of Equilibrium Equilibrium is the response to head Semicircular movements canals Ampulla Equilibrium receptors of the inner ear Vestibular are called the vestibular apparatus nerve Vestibular apparatus has two functional parts: 1. Static equilibrium Vestibule 2. Dynamic equilibrium (a) © 2015 Pearson Education, Limited. Static Equilibrium Maintenance of the proper head position in Membranes in vestibule response to changes in linear motion such as walking Maculae—receptors in the vestibule Report on the position of the head When body is not moving Otoliths Works with gravity Otolithic membrane Anatomy of the maculae Hair tuft Hair cells (maculae) are embedded in the otolithic Hair cell membrane Supporting cell Otoliths (tiny stones) roll in response to changes in pull of gravity Nerve fibers of (a) vestibular division Movements cause otoliths to bend the hair cells of cranial nerve VIII static equilibrium receptors). Figure 8.13b Structure and function of maculae ( Force of Otolithic Otoliths gravity membrane Hair cell Head upright Head tilted (b) Dynamic Equilibrium These receptors respond to angular or rotary Semicircular movements canals In the ampulla of the semicircular canal Ampulla Hair cells responds to these movements Vestibular nerve Action of angular head movements The movement cause a gel like structure (cupula) to bend the hair cells An impulse is sent via the vestibular nerve to Vestibule the cerebellum (a) Figure 8.14b Structure and function of the crista ampullaris (dynamic equilibrium receptor region). Ampulla Endolymph Flow of endolymph (b) Cupula of crista ampullaris Cupula Nerve fibers Direction of body (c) movement Hearing and Equilibrium Deficits Deafness is any degree of hearing loss Conduction deafness Transmission of sound vibrations through the external and middle ears is hindered Sensorineural deafness Damage to the nervous system structures involved in hearing Ménière’s syndrome affects the inner ear and causes progressive deafness and perhaps vertigo (sensation of spinning) Chemical Senses: Taste and Smell Both senses use chemoreceptors Stimulated by chemicals in solution Smell can differentiate a large range of chemicals Both senses complement each other and respond to many of the same stimuli Olfaction—The Sense of Smell Olfactory receptors in roof of nasal cavity Olfactory receptors cells (neurons) with long cilia known as olfactory hairs detect chemicals Chemicals must be dissolved in mucus for detection by chemoreceptors called olfactory receptors Impulses are transmitted via the olfactory filaments to the olfactory nerve Interpretation of smells is made in the cortex © 2015 Pearson Education, Limited. Figure 8.18 Location and cellular makeup of the olfactory epithelium. Olfactory bulb Cribriform plate of ethmoid bone Olfactory tract Olfactory filaments of the olfactory nerve Supporting cell Olfactory Olfactory mucosa receptor cell Olfactory hairs Mucus layer (cilia) (a) Route of inhaled air containing odor molecules (b) Taste Buds and the Sense of Taste Epiglottis Taste buds house the receptor organs Palatine tonsil Locations of taste buds Lingual tonsil Most are on the tongue Soft palate Cheeks The tongue is covered with projections called papillae Taste buds are found on the sides of papillae Fungiform © 2015 Pearson Education, Limited. papillae (a) Figure 8.19b Location and structure of taste buds. Vallate papilla Taste buds (b) Taste Sensations 1. Sweet receptors respond to sugars, saccharine, some amino acids 2. Sour receptors respond to Hions or acids 3. Bitter receptors respond to alkaloids 4. Salty receptors respond to metal ions 5. Umami receptors respond to the amino acid glutamate or the beefy taste of meat © 2015 Pearson Education, Limited.
