Chapter 15: Special Senses

Circumvallate papilla Connective tissue Gustatory receptor cells Figure 15.23: Location and structure of taste buds on the tongue, p. 581. Taste fibers of cranial nerve Gustatory hair Epiglottis Taste pore Palatine tonsil Lingual tonsil Basal cell Foliate papillae Circumvallate papilla Connective tissue Gustatory receptor cells Stratified squamous epithelium of tongue (c) Gustatory (taste) cells Taste pore Connective tissue Basal cells (b) Taste bud Fungiform papillae (a) (d)

Figure 15.24: The gustatory pathway, p. 583. cortex (in insula) Thalamic nucleus (ventral posterior medial nucleus) Pons Solitary nucleus in medulla oblongata Facial nerve (VII) Vagus (nerve X) Glosso- pharyngeal nerve (IX)

Figure 5.21: Olfactory receptors, p. 579. epithelium Frontal lobe of cerebrum Olfactory tract Mitral cell Olfactory tract Olfactory bulb Glomeruli Nasal conchae Cribriform plate of ethmoid bone Filaments of olfactory nerve Lamina propria connective tissue Route of inhaled air Olfactory gland Axon Basal cell Olfactory receptor cell Olfactory epithelium Supporting cell Dendrite Mucus Olfactory cilia Route of inhaled air containing odor molecules

Figure 5.22: Olfactory transduction process, p. 580. Extracellular fluid Na+ Odorant Adenylate cyclase Ca2+ 1 cAMP 2 3 GTP GTP 4 Receptor Golf GTP GDP ATP cAMP 5 Cytoplasm

George Wald 1906 – 1997 received the Nobel Prize in 1967 for discoveries concerning the primary physiological and chemical visual processes in the eye

Figure 15.1a: The eye and associated accessory structures, p. 557. Site where conjunctiva merges with cornea Eyebrow Eyelid Eyelashes Pupil Palpebral fissure Lacrimal caruncle Medial commissure (canthus) Lateral commissure (canthus) Sclera (covered by conjunctiva) Iris Eyelid (a)

Figure 15.1b: The eye and associated accessory structures, p. 557. Levator palpebrae superioris muscle Orbicularis oculi muscle Eyebrow Tarsal plate Palpebral conjunctiva Tarsal glands Cornea Palpebral fissure Eyelashes Bulbar conjunctiva Conjunctival sac Orbicularis oculi muscle (b)

Figure 15.2: The lacrimal apparatus, p. 558. gland Lacrimal sac Excretory ducts of lacrimal gland Lacrimal punctum Lacrimal canaliculus Nasolacrimal duct Inferior meatus of nasal cavity Nostril

Figure 15.3: Extrinsic eye muscles, p. 559. Trochlea Superior oblique muscle Superior oblique tendon Superior rectus muscle Axis at center of eye Lateral rectus muscle Conjunctiva Inferior rectus muscle Medial rectus muscle Lateral rectus muscle Optic nerve Inferior rectus muscle Inferior oblique muscle Annular ring (a) (b) Controlling cranial nerve Name Action Lateral rectus Moves eye laterally VI (abducens) Medial rectus Moves eye medially III (oculomotor) Superior rectus Elevates eye and turns it medially III (oculomotor) Inferior rectus Depresses eye and turns it medially III (oculomotor) Inferior oblique Elevates eye and turns it laterally III (oculomotor) Superior oblique Depresses eye and turns it laterally IV (trochlear) (c)

Posterior segment (cavity) (contains vitreous humor) Optic disc Figure 15.4a: Internal structure of the eye (sagittal section), p. 560. Ora serrata Sclera Ciliary body Choroid Ciliary zonule (suspensory ligament) Retina Macula lutea Cornea Fovea centralis Iris Pupil Posterior pole Anterior pole Optic nerve Anterior segment (cavity) Lens Scleral venous sinus (Canal of Schlemm) Central artery and vein of the retina Posterior segment (cavity) (contains vitreous humor) Optic disc (blind spot) (a)

Figure 15.6b: Microscopic anatomy of the retina, p. 562. Pigmented layer of retina Neural layer of retina Central artery and vein of retina Optic disc Sclera Optic nerve Choroid (b)

Figure 15.6a: Microscopic anatomy of the retina, p. 562. Pigmented layer of retina Horizontal cell Rod Cone Bipolar cells Amacrine cell Ganglion cells (a) Pathway of light

Figure 15.13: Focusing for distant and close vision, p. 567. Sympathetic + Nearly parallel rays from distant object Lens Ciliary zonule Ciliary muscle Inverted image Ciliary muscle Lens (a) Lens is flattened for distant vision Ciliary zonule (suspensory ligaments) Parasympathetic + Divergent rays from close object Inverted image (c) Anterior segment viewed from behind (b) Lens bulges for close vision

Figure 15.15: Photoreceptors of the retina, p. 570. Process of bipolar cell Light Light Light Synaptic terminals Inner fibers Rod cell body Rod cell body Nuclei Cone cell body Mitochondria Outer fiber Retinal (b) Opsin Inner segment Connecting cilia Apical microvillus Outer segment Discs being phagocytized Pigmented layer Discs containing visual pigments Pigment cell nucleus Melanin granules Basal lamina (border with choroid) (a)

(contralateral) fiber Lateral geniculate body of thalamus Figure 5.19: Visual fields of the eyes and visual pathway to the brain, inferior view, p. 576. Fixation point Right eye Left eye Optic nerve Supra- chiasmatic nucleus Pretectal nucleus Optic chiasma Optic tract Lateral geniculate body Superior colliculus (sectioned) Uncrossed (ipsilateral) fiber Crossed (contralateral) fiber Lateral geniculate body of thalamus Optic radiation Superior colliculus Occipital lobe (visual cortex) Corpus callosum (a) (b)

Figure 15.25a: Structure of the ear, p. 584. Internal (inner) ear (labryinth) External (outer) ear Middle ear Auricle (pinna) Helix External acoustic meatus Lobule Pharyngotympanic (auditory) tube Tympanic membrane (a)

Figure 15.25b: Structure of the ear, p. 584. Entrance to mastoid antrum in the epitympanic recess Auditory ossicles Malleus (hammer) Semicircular canals Incus (anvil) Vestibule Stapes (stirrup) Vestibular nerve External acoustic meatus Cochlear nerve Cochlea Tympanic membrane Oval window (deep to stapes) Pharyngotympanic (auditory) tube Internal jugular vein Round window (b)

Malleus Incus Epitympanic recess Superior Anterior Pharyngotym- Figure 5.26: The three auditory ossicles in the right middle ear, p. 585. Malleus Incus Epitympanic recess Superior Anterior Pharyngotym- panic tube Tensor tympani muscle Tympanic membrane (medial view) Stapes Stapedius muscle

Figure 5.27: Membranous labyrinth of the internal ear, p. 586. Temporal bone Semicircular ducts in semicircular canals: Facial nerve Vestibular nerve • Anterior Superior vestibular ganglion • Posterior Inferior vestibular ganglion • Lateral Cochlear nerve Cristae ampullares in the ampullae Maculae Spiral organ (of Corti) Utricle in vestibule Saccule in vestibule Cochlear duct in cochlea Stapes in oval window Round window

Figure 5.29: Sound: source and propagation, p. 589. Area of compressed molecules Area of rarefaction Wavelength Crest Air pressure Trough (a) (b) Time Amplitude (c)

Figure 15.31: Route of sound waves through the ear, p. 590. External ear Middle ear Internal ear Air External acoustic meatus Malleus, incus, stapes (ossicles) Oval window Fluids in cochlear canals Tympanic membrane Pinna Upper and middle Lower Pressure Time Spiral organ (of Corti) stimulated One vibration Amplitude Amplification in middle ear

Figure 15.35: Structure of a macula, p. 594. Macula of saccule Macula of utricle Kinocilium Stereocilia Otoliths Otolithic membrane Hair bundle Hair cells Supporting cells Vestibular nerve fibers

Otolithic membrane Kinocilium Ster eocilia Depolarization Figure 15.36: The effect of gravitational pull on a macula receptor cell in the utricle, p. 595. Otolithic membrane Kinocilium Ster eocilia Depolarization Hyperpolarization Receptor potential (Hairs bent towar kinocilium) d (Hairs bent away from kinocilium) Nerve impulses generated in vestibular fiber Increased impulse frequency Decreased impulse frequency Excitation Inhibition

Figure 15.37: Location and sturcture of a crista ampullaris, p. 596. Flow of endolymph (a) Crista ampullaris Fibers of vestibular nerve Cupula (b) Turning motion Ampulla of left ear Ampulla of right ear Cupula Cupula at rest Position of cupula during turn Position of cupula during turn Fluid motion in ducts Increased firing Horizontal ducts Decreased firing (c) (d) Afferent fibers of vestibular nerve

Figure 15.38: Pathways of the balance and orientation system, p. 597. Vestibular receptors Visual receptors Somatic receptors Input Vestibular nuclear complex Reticular nuclei Cerebellum Central nervous system processing Oculomotor control (cranial nerve nuclei III, IV, VI) (eye movements) Spinal motor control (cranial nerve nuclei XI and vestibulospinal tracts) (neck movements) Output