Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 17-3
Transcript
17- Lab The Special Senses PowerPoint® Lecture Presentations prepared by Jason LaPres Lone Star College—North Harris 1 © 2012 Pearson Education, Inc. An Introduction to the Special Senses • Learning Outcomes • 17-1 Describe the sensory organs of smell, trace the olfactory pathways to their destinations in the brain, and explain the physiological basis of olfactory discrimination. • 17-2 Describe the sensory organs of taste, trace the gustatory pathways to their destinations in the brain, and explain the physiological basis of gustatory discrimination. • 17-3 Identify the internal and accessory structures of the eye, and explain the functions of each. 2 © 2012 Pearson Education, Inc. An Introduction to the Special Senses • Learning Outcomes • 17-4 Explain color and depth perception, describe how light stimulates the production of nerve impulses, and trace the visual pathways to their destinations in the brain. • 17-5 Describe the structures of the external, middle, and internal ear, explain their roles in equilibrium and hearing, and trace the pathways for equilibrium and hearing to their destinations in the brain. 3 © 2012 Pearson Education, Inc. An Introduction to the Special Senses • Five Special Senses 1. Olfaction 2. Gustation 3. Vision 4. Equilibrium 5. Hearing 4 © 2012 Pearson Education, Inc. 17-1 Smell (Olfaction) • Olfactory Organs • Provide sense of smell • Located in nasal cavity on either side of nasal septum • Made up of two layers 1. Olfactory epithelium 2. Lamina propria 5 © 2012 Pearson Education, Inc. 17-1 Smell (Olfaction) • Layers of Olfactory Organs • Olfactory epithelium contains: • Olfactory receptors • Supporting cells • Basal (stem) cells 6 © 2012 Pearson Education, Inc. 17-1 Smell (Olfaction) • Layers of Olfactory Organs • Lamina propria contains: • Areolar tissue • Blood vessels • Nerves • Olfactory glands 7 © 2012 Pearson Education, Inc. Figure 17-1a The Olfactory Organs Olfactory Pathway to the Cerebrum Olfactory Olfactory Olfactory epithelium nerve bulb fibers (N I) Olfactory tract Central nervous system Cribriform plate Superior nasal concha The olfactory organ on the left side of the nasal septum © 2012 Pearson Education, Inc. 8 Figure 17-1b The Olfactory Organs Basal cell: divides to replace To worn-out olfactory olfactory receptor cells Olfactory bulb gland Cribriform plate Lamina propria Olfactory nerve fibers Developing olfactory receptor cell Olfactory receptor cell Olfactory epithelium Supporting cell Mucous layer Knob Subsance being smelled © 2012 Pearson Education, Inc. An olfactory receptor is a modified neuron with multiple cilia extending from its free surface. Olfactory cilia: surfaces contain receptor proteins (see Spotlight Fig. 173) 9 17-1 Smell (Olfaction) • Olfactory Glands • Secretions coat surfaces of olfactory organs • Olfactory Receptors • Highly modified neurons • Olfactory reception • Involves detecting dissolved chemicals as they interact with odorant-binding proteins 10 © 2012 Pearson Education, Inc. 17-2 Taste (Gustation) • Gustation • Provides information about the foods and liquids consumed • Taste Receptors (Gustatory Receptors) • Are distributed on tongue and portions of pharynx and larynx • Clustered into taste buds 11 © 2012 Pearson Education, Inc. 17-2 Taste (Gustation) • Taste Buds • Associated with epithelial projections (lingual papillae) on superior surface of tongue 12 © 2012 Pearson Education, Inc. 17-2 Taste (Gustation) • Three Types of Lingual Papillae 1. Filiform papillae • Provide friction • Do not contain taste buds 2. Fungiform papillae • Contain five taste buds each 3. Circumvallate papillae • Contain 100 taste buds each 13 © 2012 Pearson Education, Inc. 17-2 Taste (Gustation) • Taste Buds • Contain: • Basal cells • Gustatory cells • Extend taste hairs through taste pore • Survive only 10 days before replacement • Monitored by cranial nerves that synapse within solitary nucleus of medulla oblongata • Then on to thalamus and primary sensory cortex 14 © 2012 Pearson Education, Inc. Figure 17-3a Gustatory Receptors Water receptors (pharynx) Umami Sour Bitter Salty Sweet Landmarks and receptors on the tongue © 2012 Pearson Education, Inc. 15 Figure 17-3b Gustatory Receptors Taste buds Circumvallate papilla Fungiform papilla Filiform papillae The structure and representative locations of the three types of lingual papillae. Taste receptors are located in taste buds, which form pockets in the epithelium of fungiform or circumvillate papillae. © 2012 Pearson Education, Inc. 16 Figure 17-3c Gustatory Receptors Taste buds Taste buds LM 280 Taste bud LM 650 Nucleus of transitional cell Nucleus of gustatory cell Nucleus of basal cell Transitional cell Gustatory cell Basal cell Taste hairs (microvilli) Taste pore Taste buds in a circumvallate papilla. A diagrammatic view of a taste bud, showing gustatory (receptor) cells and supporting cells. © 2012 Pearson Education, Inc. 17 17-2 Taste (Gustation) • Gustatory Discrimination • Four primary taste sensations 1. Sweet 2. Salty 3. Sour 4. Bitter 18 © 2012 Pearson Education, Inc. 17-2 Taste (Gustation) • Additional Human Taste Sensations • Umami • Characteristic of beef/chicken broths and Parmesan cheese • Receptors sensitive to amino acids, small peptides, and nucleotides • Water • Detected by water receptors in the pharynx 19 © 2012 Pearson Education, Inc. 17-2 Taste (Gustation) • Gustatory Discrimination • Dissolved chemicals contact taste hairs • Bind to receptor proteins of gustatory cell • Salt and sour receptors • Chemically gated ion channels • Stimulation produces depolarization of cell • Sweet, bitter, and umami stimuli • G proteins • Gustducins 20 © 2012 Pearson Education, Inc. Figure 14-21 Cranial Nerves Controlling the Extra-Ocular Muscles Superior rectus muscle Superior oblique muscle OPTIC NERVE (N II) Optic chiasm OCULOMOTOR NERVE (N III) TROCHLEAR NERVE (N IV) Trochlea Levator palpebrae superioris muscle Trigeminal nerve (N V), cut Inferior oblique muscle Vestibulocochlear nerve (N VIII), cut Inferior rectus muscle Ciliary ganglion Medial rectus muscle Facial nerve (N VII), cut Lateral rectus muscle (cut) ABDUCENS NERVE (N VI) 21 © 2012 Pearson Education, Inc. Extrinsic Eye Muscles • External muscles that rotate the eyeball • Originate on surface of the eyeball (sclera) • 4 rectus muscles – attach straight behind the eyeball • Superior rectus (N III) • Inferior rectus (N III) • Medial rectus (N III) • Lateral rectus (N VI) • 2 oblique muscles – attach from the side of the eyeball • Superior oblique (N IV) – along medial wall, passes through trochlea (loop on medial wall of orbit) and turns laterally • Inferior oblique (N III) – from lateral wall of orbit, on inferior 22 side of eyeball © 2012 Pearson Education, Inc. Extrinsic Eye Muscles 23 © 2012 Pearson Education, Inc. Figure 11–5c Extrinsic Eye Muscles 24 © 2012 Pearson Education, Inc. Figure 11–5a, b Summary: Extrinsic Eye Muscles 25 © 2012 Pearson Education, Inc. Table 11–3 17-3 Accessory Structures of the Eye • Accessory Structures of the Eye • Provide protection, lubrication, and support • Include: • The palpebrae (eyelids) • The superficial epithelium of eye • The lacrimal apparatus 26 © 2012 Pearson Education, Inc. 17-3 Accessory Structures of the Eye • Eyelids (Palpebrae) • Continuation of skin • Blinking keeps surface of eye lubricated, free of dust and debris • Palpebral fissure • Gap that separates free margins of upper and lower eyelids 27 © 2012 Pearson Education, Inc. 17-3 Accessory Structures of the Eye • Eyelids (Palpebrae) • Medial canthus and lateral canthus • Where two eyelids are connected • Eyelashes • Robust hairs that prevent foreign matter from reaching surface of eye 28 © 2012 Pearson Education, Inc. 17-3 Accessory Structures of the Eye • Eyelids (Palpebrae) • Tarsal glands • Secrete lipid-rich product that helps keep eyelids from sticking together 29 © 2012 Pearson Education, Inc. 17-3 Accessory Structures of the Eye • Superficial Epithelium of Eye • Lacrimal caruncle • Mass of soft tissue • Contains glands producing thick secretions • Contributes to gritty deposits that appear after good night’s sleep • Conjunctiva • Epithelium covering inner surfaces of eyelids (palpebral conjunctiva) and outer surface of eye (ocular conjunctiva) 30 © 2012 Pearson Education, Inc. Figure 17-4a External Features and Accessory Structures of the Eye Eyelashes Pupil Lateral canthus Palpebra Palpebral fissure Sclera Medial canthus Lacrimal caruncle Corneal limbus Gross and superficial anatomy of the accessory structures 31 © 2012 Pearson Education, Inc. 17-3 Accessory Structures of the Eye • Lacrimal Apparatus • Produces, distributes, and removes tears • Fornix • Pocket where palpebral conjunctiva joins ocular conjunctiva • Lacrimal gland (tear gland) • Secretions contain lysozyme, an antibacterial enzyme 32 © 2012 Pearson Education, Inc. 17-3 Accessory Structures of the Eye • Tears • Collect in the lacrimal lake • Pass through: • Lacrimal puncta • Lacrimal canaliculi • Lacrimal sac • Nasolacrimal duct • To reach inferior meatus of nose 33 © 2012 Pearson Education, Inc. Figure 17-4b External Features and Accessory Structures of the Eye Superior Tendon of superior rectus muscle oblique muscle Lacrimal gland ducts Lacrimal punctum Lacrimal gland Lacrimal caruncle Ocular conjunctiva Superior lacrimal canaliculus Medial canthus Inferior lacrimal canaliculus Lacrimal sac Lateral canthus Lower eyelid Orbital fat Inferior rectus muscle Nasolacrimal duct Inferior oblique muscle Inferior nasal concha Opening of nasolacrimal duct The organization of the lacrimal apparatus. 34 © 2012 Pearson Education, Inc. 17-3 The Eye • Three Layers of the Eye 1. Outer fibrous layer 2. Intermediate vascular layer 3. Deep inner layer 35 © 2012 Pearson Education, Inc. 17-3 The Eye • Eyeball • Is hollow • Is divided into two cavities 1. Large posterior cavity 2. Smaller anterior cavity 36 © 2012 Pearson Education, Inc. Figure 17-5a The Sectional Anatomy of the Eye Fornix Palpebral conjunctiva Eyelash Ocular conjunctiva Optic nerve Ora serrata Cornea Lens Pupil Iris Limbus Fovea Retina Choroid Sclera Sagittal section of left eye 37 © 2012 Pearson Education, Inc. Figure 17-5b The Sectional Anatomy of the Eye Fibrous layer Cornea Anterior cavity Sclera Vascular layer (uvea) Iris Ciliary body Choroid Neural layer (retina) Posterior cavity Neural part Pigmented part Horizontal section of right eye 38 © 2012 Pearson Education, Inc. Figure 17-5c The Sectional Anatomy of the Eye Visual axis Anterior cavity Cornea Posterior Anterior Edge of pupil chamber chamber Iris Suspensory ligament of lens Nose Corneal limbus Conjunctiva Lacrimal punctum Lacrimal caruncle Lower eyelid Medial canthus Ciliary processes Lateral canthus Lens Ciliary body Ora serrata Sclera Choroid Retina Posterior cavity Ethmoidal labyrinth Lateral rectus muscle Medial rectus muscle Optic disc Fovea Optic nerve Orbital fat Central artery and vein Horizontal dissection of right eye © 2012 Pearson Education, Inc. 39 17-3 The Eye • The Fibrous Layer • Sclera (white of the eye) • Cornea • Corneal limbus (border between cornea and sclera) 40 © 2012 Pearson Education, Inc. 17-3 The Eye • Vascular Layer (Uvea) Functions 1. Provides route for blood vessels and lymphatics that supply tissues of eye 2. Regulates amount of light entering eye 3. Secretes and reabsorbs aqueous humor that circulates within chambers of eye 4. Controls shape of lens, which is essential to focusing 41 © 2012 Pearson Education, Inc. Figure 17-5c The Sectional Anatomy of the Eye Visual axis Anterior cavity Cornea Posterior Anterior Edge of pupil chamber chamber Iris Suspensory ligament of lens Nose Corneal limbus Conjunctiva Lacrimal punctum Lacrimal caruncle Lower eyelid Medial canthus Ciliary processes Lateral canthus Lens Ciliary body Ora serrata Sclera Choroid Retina Posterior cavity Ethmoidal labyrinth Lateral rectus muscle Medial rectus muscle Optic disc Fovea Optic nerve Orbital fat Central artery and vein Horizontal dissection of right eye © 2012 Pearson Education, Inc. 42 17-3 The Eye • The Vascular Layer • Iris • Contains papillary muscles • Change diameter of pupil 43 © 2012 Pearson Education, Inc. Figure 17-6 The Pupillary Muscles Pupillary constrictor (sphincter) Pupil The pupillary dilator muscles extend radially away from the edge of the pupil. Contraction of these muscles enlarges the pupil. Pupillary dilator (radial) Decreased light intensity Increased sympathetic stimulation The pupillary constrictor muscles form a series of concentric circles around the pupil. When these sphincter muscles contract, the diameter of the pupil decreases. Increased light intensity Increased parasympathetic stimulation 44 © 2012 Pearson Education, Inc. 17-3 The Eye • The Vascular Layer • Ciliary Body • Extends posteriorly to level of ora serrata • Serrated anterior edge of thick, inner portion of neural tunic • Contains ciliary processes, and ciliary muscle that attaches to suspensory ligaments of lens 45 © 2012 Pearson Education, Inc. 17-3 The Eye • The Vascular Layer • The choroid • Vascular layer that separates fibrous and inner layers posterior to ora serrata • Delivers oxygen and nutrients to retina 46 © 2012 Pearson Education, Inc. 17-3 The Eye • The Inner Layer • Outer layer called pigmented part • Inner called neural part (retina) • Contains visual receptors and associated neurons • Rods and cones are types of photoreceptors • Rods • Do not discriminate light colors • Highly sensitive to light • Cones • Provide color vision • Densely clustered in fovea, at center of macula 47 © 2012 Pearson Education, Inc. Figure 17-5c The Sectional Anatomy of the Eye Visual axis Anterior cavity Cornea Posterior Anterior Edge of pupil chamber chamber Iris Suspensory ligament of lens Nose Corneal limbus Conjunctiva Lacrimal punctum Lacrimal caruncle Lower eyelid Medial canthus Ciliary processes Lateral canthus Lens Ciliary body Ora serrata Sclera Choroid Retina Posterior cavity Ethmoidal labyrinth Lateral rectus muscle Medial rectus muscle Optic disc Fovea Optic nerve Orbital fat Central artery and vein Horizontal dissection of right eye © 2012 Pearson Education, Inc. 48 Figure 17-7a The Organization of the Retina Horizontal cell Cone Rod Pigmented part of retina Rods and cones Amacrine cell Bipolar cells Ganglion cells LIGHT The cellular organization of the retina. The photoreceptors are closest to the choroid, rather than near the posterior cavity (vitreous chamber). © 2012 Pearson Education, Inc. 49 Figure 17-7a The Organization of the Retina Choroid Pigmented part of retina Rods and cones Bipolar cells Ganglion cells Retina LM 350 Nuclei of Nuclei of rods Nuclei of ganglion cells and cones bipolar cells The cellular organization of the retina. The photoreceptors are closest to the choroid, rather than near the posterior cavity (vitreous chamber). © 2012 Pearson Education, Inc. 50 Figure 17-7b The Organization of the Retina Pigmented Neural part part of retina of retina Central retinal vein Optic disc Central retinal artery Sclera Optic nerve © 2012 Pearson Education, Inc. Choroid The optic disc in diagrammatic sagittal section. 51 Figure 17-7c The Organization of the Retina Fovea Macula Optic disc (blind spot) Central retinal artery and vein emerging from center of optic disc A photograph of the retina as seen through the pupil. © 2012 Pearson Education, Inc. 52 17-3 The Eye • Inner Neural Part • Bipolar cells • Neurons of rods and cones synapse with ganglion cells • Horizontal cells • Extend across outer portion of retina • Amacrine cells • Comparable to horizontal cell layer • Where bipolar cells synapse with ganglion cells 53 © 2012 Pearson Education, Inc. 17-3 The Eye • Horizontal and Amacrine Cells • Facilitate or inhibit communication between photoreceptors and ganglion cells • Alter sensitivity of retina • Optic Disc • Circular region just medial to fovea • Origin of optic nerve • Blind spot 54 © 2012 Pearson Education, Inc. Figure 17-8 A Demonstration of the Presence of a Blind Spot 55 © 2012 Pearson Education, Inc. 17-3 The Eye • The Chambers of the Eye • Ciliary body and lens divide eye into: • Large posterior cavity (vitreous chamber) • Smaller anterior cavity • Anterior chamber • Extends from cornea to iris • Posterior chamber • Between iris, ciliary body, and lens 56 © 2012 Pearson Education, Inc. 17-3 The Eye • Aqueous Humor • Fluid circulates within eye • Diffuses through walls of anterior chamber into scleral venous sinus (canal of Schlemm) • Re-enters circulation • Intraocular Pressure • Fluid pressure in aqueous humor • Helps retain eye shape 57 © 2012 Pearson Education, Inc. Figure 17-9 The Circulation of Aqueous Humor Cornea Anterior cavity Pupil Anterior chamber Scleral venous sinus Posterior chamber Body of iris Ciliary process Lens Suspensory ligaments Pigmented epithelium Conjunctiva Ciliary body Sclera Posterior cavity (vitreous chamber) Choroid Retina 58 © 2012 Pearson Education, Inc. 17-3 The Eye • Large Posterior Cavity (Vitreous Chamber) • Vitreous body • Gelatinous mass • Helps stabilize eye shape and supports retina 59 © 2012 Pearson Education, Inc. 17-3 The Eye • The Lens • Lens fibers • Cells in interior of lens • No nuclei or organelles • Filled with crystallins, which provide clarity and focusing power to lens • Cataract • Condition in which lens has lost its transparency 60 © 2012 Pearson Education, Inc. 17-5 The Ear • The External Ear • Auricle • Surrounds entrance to external acoustic meatus • Protects opening of canal • Provides directional sensitivity 61 © 2012 Pearson Education, Inc. 17-5 The Ear • The External Ear • External acoustic meatus • Ends at tympanic membrane (eardrum) • Tympanic membrane • Is a thin, semitransparent sheet • Separates external ear from middle ear 62 © 2012 Pearson Education, Inc. Figure 17-21 The Anatomy of the Ear Middle Ear External Ear Elastic cartilages Internal Ear Auditory ossicles Oval window Semicircular canals Petrous part of temporal bone Auricle Facial nerve (N VII) Vestibulocochlear nerve (N VIII) Bony labyrinth of internal ear Cochlea Tympanic cavity Auditory tube To nasopharynx External acoustic meatus Tympanic membrane Round Vestibule window 63 © 2012 Pearson Education, Inc. 17-5 The Ear • The External Ear • Ceruminous glands • Integumentary glands along external acoustic meatus • Secrete waxy material (cerumen) • Keeps foreign objects out of tympanic membrane • Slows growth of microorganisms in external acoustic meatus 64 © 2012 Pearson Education, Inc. 17-5 The Ear • The Middle Ear • Also called tympanic cavity • Communicates with nasopharynx via auditory tube • Permits equalization of pressures on either side of tympanic membrane • Encloses and protects three auditory ossicles 1. Malleus (hammer) 2. Incus (anvil) 3. Stapes (stirrup) 65 © 2012 Pearson Education, Inc. Figure 17-22a The Middle Ear Auditory Ossicles Malleus Incus Stapes Temporal bone (petrous part) Stabilizing ligaments Oval window Branch of facial nerve VII (cut) Muscles of the Middle Ear Tensor tympani muscle External acoustic meatus Stapedius muscle Tympanic cavity (middle ear) Tympanic membrane Round window Auditory tube The structures of the middle ear. 66 © 2012 Pearson Education, Inc. Figure 17-22b The Middle Ear Malleus attached to tympanic membrane Malleus Tendon of tensor tympani muscle Incus Base of stapes at oval window Stapes Stapedius muscle Inner surface of tympanic membrane The tympanic membrane and auditory ossicles © 2012 Pearson Education, Inc. 67 17-5 The Ear • Vibration of Tympanic Membrane • Converts arriving sound waves into mechanical movements • Auditory ossicles conduct vibrations to inner ear • Tensor tympani muscle • Stiffens tympanic membrane • Stapedius muscle • Reduces movement of stapes at oval window 68 © 2012 Pearson Education, Inc. 17-5 The Ear • The Internal Ear • Contains fluid called endolymph • Bony labyrinth surrounds and protects membranous labyrinth • Subdivided into: • Vestibule • Semicircular canals • Cochlea 69 © 2012 Pearson Education, Inc. Figure 17-23b The Internal Ear KEY Membranous labyrinth Semicircular ducts Anterior Lateral Posterior Bony labyrinth Vestibule Cristae within ampullae Maculae Endolymphatic sac Semicircular canal Cochlea Utricle Saccule Vestibular duct Cochlear duct Tympanic Spiral duct organ The bony and membranous labyrinths. Areas of the membranous labyrinth containing sensory receptors (cristae, maculae, and spiral organ) are shown in purple. 70 © 2012 Pearson Education, Inc. Figure 17-23a The Internal Ear Perilymph Bony labyrinth Endolymph KEY Membranous labyrinth Bony labyrinth Membranous labyrinth A section through one of the semicircular canals, showing the relationship between the bony and membranous labyrinths, and the boundaries of perilymph and endolymph. 71 © 2012 Pearson Education, Inc. 17-5 The Ear • The Internal Ear • Vestibule • Encloses saccule and utricle • Receptors provide sensations of gravity and linear acceleration • Semicircular canals • Contain semicircular ducts • Receptors stimulated by rotation of head 72 © 2012 Pearson Education, Inc. 17-5 The Ear • The Internal Ear • Cochlea • Contains cochlear duct (elongated portion of membranous labyrinth) • Receptors provide sense of hearing 73 © 2012 Pearson Education, Inc. 17-5 The Ear • The Internal Ear • Round window • Thin, membranous partition • Separates perilymph from air spaces of middle ear • Oval window • Formed of collagen fibers • Connected to base of stapes 74 © 2012 Pearson Education, Inc. 17-5 The Ear • Stimuli and Location • Sense of gravity and acceleration • From hair cells in vestibule • Sense of rotation • From semicircular canals • Sense of sound • From cochlea 75 © 2012 Pearson Education, Inc. 17-5 The Ear • Equilibrium • Sensations provided by receptors of vestibular complex • Hair cells • Basic receptors of inner ear • Provide information about direction and strength of mechanical stimuli 76 © 2012 Pearson Education, Inc. 17-5 The Ear • The Semicircular Ducts • Are continuous with utricle • Each duct contains: • Ampulla with gelatinous cupula • Associated sensory receptors • Stereocilia – resemble long microvilli • Are on surface of hair cell • Kinocilium – single large cilium 77 © 2012 Pearson Education, Inc. Figure 17-24a The Semicircular Ducts Vestibular branch (N VIII) Semicircular ducts Anterior Posterior Lateral Cochlea Ampulla Endolymphatic sac Endolymphatic duct Utricle Saccule Maculae An anterior view of the right semicircular ducts, the utricle, and the saccule, showing the locations of sensory receptors 78 © 2012 Pearson Education, Inc. Figure 17-24b The Semicircular Ducts Ampulla filled with endolymph Cupula Hair cells Crista Supporting cells Sensory nerve A cross section through the ampulla of a semicircular duct © 2012 Pearson Education, Inc. 79 Figure 17-24c The Semicircular Ducts Direction of relative endolymph movement Direction of duct rotation Direction of duct rotation Semicircular duct Ampulla At rest Endolymph movement along the length of the duct moves the cupula and stimulates the hair cells. 80 © 2012 Pearson Education, Inc. Figure 17-24d The Semicircular Ducts Displacement in this direction stimulates hair cell Kinocilium Displacement in this direction inhibits hair cell Stereocilia Hair cell Sensory nerve ending Supporting cell © 2012 Pearson Education, Inc. A representative hair cell (receptor) from the vestibular complex. Bending the sterocilia toward the kinocilium depolarizes the cell and stimulates the sensory neuron. Displacement in the opposite direction inhibits the sensory neuron. 81 17-5 The Ear • The Utricle and Saccule • Provide equilibrium sensations • Are connected with the endolymphatic duct, which ends in endolymphatic sac 82 © 2012 Pearson Education, Inc. 17-5 The Ear • The Utricle and Saccule • Maculae • Oval structures where hair cells cluster • Statoconia • Densely packed calcium carbonate crystals on surface of gelatinous mass • Otolith (ear stone) = gelatinous matrix and statoconia 83 © 2012 Pearson Education, Inc. Figure 17-25ab The Saccule and Utricle The location of the maculae Gelatinous material Statoconia Otolith Hair cells Nerve fibers The structure of an individual macula © 2012 Pearson Education, Inc. 84 Figure 17-25c The Saccule and Utricle Head in normal, upright position Gravity Head tilted posteriorly Receptor output increases Gravity Otolith moves “downhill,” distorting hair cell processes A diagrammatic view of macular function when the head is held horizontally 1 and then tilted back 2 © 2012 Pearson Education, Inc. 85 17-5 The Ear • Pathways for Equilibrium Sensations • Vestibular receptors • Activate sensory neurons of vestibular ganglia • Axons form vestibular branch of vestibulocochlear nerve (VIII) • Synapse within vestibular nuclei 86 © 2012 Pearson Education, Inc. 17-5 The Ear • Hearing • Cochlear duct receptors • Provide sense of hearing 87 © 2012 Pearson Education, Inc. Figure 17-27a The Cochlea Round window Stapes at oval window Scala vestibuli Cochlear duct Scala tympani Semicircular canals Cochlear branch Vestibular branch Vestibulocochlear nerve (N VIII) The structure of the cochlea KEY From oval window to tip of spiral From tip of spiral to round window 88 © 2012 Pearson Education, Inc. Figure 17-27b The Cochlea Temporal bone (petrous part) Vestibular membrane Scala vestibuli (contains perilymph) Tectorial membrane Cochlear duct (contains endolymph) Basilar membrane Spiral organ From oval window Spiral ganglion Scala tympani (contains perilymph) To round window Cochlear nerve Vestibulocochlear nerve (N VIII) Diagrammatic and sectional views of the cochlear spiral 89 © 2012 Pearson Education, Inc. Figure 17-27b The Cochlea Vestibular membrane Basilar membrane Temporal bone (petrous part) Scala vestibuli (contains perilymph) Cochlear duct (contains endolymph) Spiral organ Spiral ganglion Scala tympani (contains perilymph) Cochlear nerve Cochlear spiral section Diagrammatic and sectional views of the cochlear spiral © 2012 Pearson Education, Inc. LM 60 90 17-5 The Ear • Hearing • Auditory ossicles • Convert pressure fluctuation in air into much greater pressure fluctuations in perilymph of cochlea • Frequency of sound • Determined by which part of cochlear duct is stimulated • Intensity (volume) • Determined by number of hair cells stimulated 91 © 2012 Pearson Education, Inc. 17-5 The Ear • Hearing • Cochlear duct receptors • Basilar membrane • Separates cochlear duct from tympanic duct • Hair cells lack kinocilia • Stereocilia in contact with overlying tectorial membrane 92 © 2012 Pearson Education, Inc. Figure 17-28a The Spiral Organ Body cochlear wall Scala vestibuli Vestibular membrane Cochlear duct Tectorial membrane Spiral ganglion Basilar membrane Scala tympani Spiral organ A three-dimensional section of the cochlea, showing the compartments, tectorial membrane, and spiral organ Cochlear branch of N VIII 93 © 2012 Pearson Education, Inc. Figure 17-28b The Spiral Organ Tectorial membrane Outer hair cell Basilar membrane Inner hair cell Nerve fibers Diagrammatic and sectional views of the receptor hair cell complex of the spiral organ 94 © 2012 Pearson Education, Inc. Figure 17-28b The Spiral Organ Cochlear duct (scala media) Vestibular membrane Tectorial membrane Scala tympani Spiral organ Basilar Hair cells Spiral ganglion cells of membrane of spiral organ cochlear nerve LM 125 Diagrammatic and sectional views of the receptor hair cell complex of the spiral organ © 2012 Pearson Education, Inc. 95
