The Special Senses—Smell Olfactory Organs Olfactory epithelium Olfactory receptor cells Neurons sensitive to odorants Supporting cells Basal (stem) cells Olfactory glands Mucus-secreting cells Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Smell The Olfactory Organs Figure 9-6(a)

The Special Senses—Smell The Olfactory Organs Figure 9-6(b)

The Special Senses—Taste Taste (Gustatory) Receptors Taste buds Found within papillae on tongue, pharynx, larynx Contain gustatory cells, supportive cells Taste hairs (cilia) extend into taste pores Sense salt, sweet, sour, bitter Also sense umami, water Synapse in medulla oblongata Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Taste Gustatory Receptors Figure 9-7(a)

The Special Senses—Taste Gustatory Receptors Figure 9-7(b)

The Special Senses Key Note Olfactory information is routed directly to the cerebrum, and olfactory stimuli have powerful effects on mood and behavior. Gustatory sensations are strongest and clearest when integrated with olfactory sensations. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Vision Accessory Structures of the Eye Eyelids (palpebra) and glands Superficial epithelium of eye Conjunctiva Lacrimal apparatus Tear production and removal Extrinsic eye muscles Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Vision The Lacrimal Apparatus Lacrimal gland produce tears Bathe conjunctiva Contain lysozyme to attack bacteria Tears drain into nasal cavity Pass through lacrimal canals, lacrimal sac, nasolacrimal duct Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Vision The Accessory Structures of the Eye Figure 9-8(a)

The Special Senses—Vision The Accessory Structures of the Eye Figure 9-8(b)

The Special Senses—Vision Extrinsic Eye Muscles Move the eye Six muscles cooperate to control gaze Superior and inferior rectus Lateral and medial rectus Superior and inferior oblique Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Vision The Extrinsic Eye Muscles Figure 9-9(a)

The Special Senses—Vision The Extrinsic Eye Muscles Figure 9-9(b)

The Special Senses—Vision Layers of the Eye Fibrous tunic Outermost layer Vascular tunic Intermediate layer Neural tunic Innermost layer Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Vision The Sectional Anatomy of the Eye Figure 9-10(a)

The Special Senses—Vision The Sectional Anatomy of the Eye Figure 9-10(b)

The Special Senses—Vision The Sectional Anatomy of the Eye Figure 9-10 (c)

The Special Senses—Vision Layers of the Eye Fibrous tunic Sclera Dense fibrous connective tissue “White of the eye” Cornea Transparent Light entrance The Eye: Light Path PLAY Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Vision Layers of the Eye Vascular tunic Iris Boundary between anterior and posterior chambers Ciliary body Ciliary muscle and ciliary process Attachment of suspensory ligaments Choroid Highly vascular Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Vision Functions of the Vascular Tunic Provide a route for blood vessels Control amount of light entering eye Adjust diameter of pupil Secrete and absorb aqueous humor Adjust lens shape for focusing Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Vision The Pupillary Muscles Figure 9-11

The Special Senses—Vision Layers of the Eye Neural tunic (Retina) Outer pigmented part Absorbs stray light Inner neural part Detects light Processes image Communicates with brain Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Vision Retinal Organization Figure 9-12(b)

The Special Senses—Vision Retinal Organization Figure 9-12(c)

The Special Senses—Vision The Aqueous Humor Secreted by ciliary processes into posterior chamber Flows into anterior chamber Maintains eye shape Carries nutrients and wastes Reabsorbed into circulation Leaves at canal of Schlemm Excess humor leads to glaucoma Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Vision Eye Chambers and the Circulation of Aqueous Humor Figure 9-14

The Special Senses—Vision The Lens Supported by suspensory ligaments Built from transparent cells Surrounded by elastic capsule Lens and cornea focus light on retina Bend light (refraction) Accommodation changes lens shape Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Vision Image Formation Figure 9-16(a)

The Special Senses—Vision Image Formation Figure 9-16(b)

The Special Senses—Vision Key Note Light passes through the cornea, crosses the anterior cavity to the lens, transits the lens, crosses the posterior chamber, and then penetrates the retina to stimulate the photoreceptors. Cones, most abundant at the fovea and macula lutea, provide detailed color vision in bright light. Rods, dominant in the peripheral retina, provide coarse color-free vision in dim light. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Vision Visual Physiology Photoreceptors—Cells specialized to respond to photons, packets of light energy Two types of photoreceptors Rods Highly sensitive, non-color vision In peripheral retina Cones Less sensitive, color vision Mostly in fovea, center of macula lutea Site of sharpest vision Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Vision The Structure of Rods and Cones Figure 9-19

The Special Senses—Vision The Visual Pathway Figure 9-21

Equilibrium and Hearing Sensory Functions of the Inner Ear Dynamic equilibrium Static equilibrium Hearing Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Equilibrium and Hearing Overview of the Ear Chambers, canals filled with fluid endolymph Bony labyrinth Surrounds membranous labyrinth Surrounded by fluid perilymph Consists of vestibule, semicircular canals, cochlea External, middle ear feed sound to cochlea Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Equilibrium and Hearing Anatomy of the Ear External ear Pinna (auricle) External acoustic canal Tympanic membrane (eardrum) Middle ear Auditory ossicles Connect tympanic membrane to inner ear Auditory tube Connection to nasopharynx Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Equilibrium and Hearing Anatomy of the Inner Ear Vestibule Membranous sacs Utricle Saccule Receptors for linear acceleration, gravity Semicircular canal with ducts Receptors for rotation Cochlea with cochlear duct Receptors for sound Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Equilibrium and Hearing Receptors of the Inner Ear Hair cells Mechanoreceptors Stereocilia on cell surface Bending excites/inhibits hair cell Information on direction and strength of mechanical stimuli Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Equilibrium and Hearing The Anatomy of the Ear Figure 9-22

Equilibrium and Hearing The Structure of the Middle Ear Figure 9-23

Equilibrium and Hearing The Anatomy of the Ear Figure 9-24(a,b)

Equilibrium and Hearing The Vestibular Complex Figure 9-25(a-c)

Equilibrium and Hearing The Vestibular Complex Figure 9-25(a, d)

Head in horizontal position Gravity Figure 9-25(e) 2 of 4 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Head in horizontal position Gravity Head tilted posteriorly Gravity Otolith moves “downhill,” distorting hair cell processes Figure 9-25(e) 3 of 4 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Ear: Balance Head in horizontal position Head tilted posteriorly Gravity Head tilted posteriorly Gravity Otolith moves “downhill,” distorting hair cell processes Receptor output increases The Ear: Balance PLAY Figure 9-25(e) 4 of 4 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Equilibrium and Hearing Overview of Hearing Sound waves vibrate tympanic membrane Ossicles transfer vibration to oval window Oval window presses on perilymph in vestibular duct Pressure wave distorts basilar membrane Hair cells of organ of Corti press on tectorial membrane Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Equilibrium and Hearing The Cochlea and the Organ of Corti Figure 9-26(a)

Equilibrium and Hearing The Cochlea and the Organ of Corti Figure 9-26(b)

External acoustic canal Cochlear branch of cranial nerve VIII Incus Oval window Malleus Stapes Vestibular duct (perilymph) Movement of sound waves Vestibular membrane Cochlear duct (endolymph) Basilar membrane Tympanic duct (perilymph) Tympanic membrane Round window Sound waves arrive at tympanic membrane. Movement of tympanic membrane causes displacement of the auditory ossicles. Movement of the stapes at the oval window establishes pressure waves in the perilymph of the vestibular duct. The pressure waves distort the basilar membrane on their way to the round window of the tympanic duct. Vibrations of the basilar membrane causes vibration of hair cells against the tectorial membrane. Information about the region and the intensity of stimulation is relayed to the CNS over the cochlear branch of cranial nerve VIII. Figure 9-27 1 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

External acoustic canal Movement of sound waves Tympanic membrane Sound waves arrive at tympanic membrane. Figure 9-27 2 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

External acoustic canal Incus Malleus Stapes Movement of sound waves Tympanic membrane Sound waves arrive at tympanic membrane. Movement of tympanic membrane causes displacement of the auditory ossicles. Figure 9-27 3 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

External acoustic canal Incus Oval window Malleus Stapes Movement of sound waves Tympanic membrane Sound waves arrive at tympanic membrane. Movement of tympanic membrane causes displacement of the auditory ossicles. Movement of the stapes at the oval window establishes pressure waves in the perilymph of the vestibular duct. Figure 9-27 4 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

External acoustic canal Incus Oval window Malleus Stapes Movement of sound waves Tympanic membrane Round window Sound waves arrive at tympanic membrane. Movement of tympanic membrane causes displacement of the auditory ossicles. Movement of the stapes at the oval window establishes pressure waves in the perilymph of the vestibular duct. The pressure waves distort the basilar membrane on their way to the round window of the tympanic duct. Figure 9-27 5 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

External acoustic canal Incus Oval window Malleus Stapes Vestibular duct (perilymph) Movement of sound waves Vestibular membrane Cochlear duct (endolymph) Basilar membrane Tympanic duct (perilymph) Tympanic membrane Round window Sound waves arrive at tympanic membrane. Movement of tympanic membrane causes displacement of the auditory ossicles. Movement of the stapes at the oval window establishes pressure waves in the perilymph of the vestibular duct. The pressure waves distort the basilar membrane on their way to the round window of the tympanic duct. Vibrations of the basilar membrane causes vibration of hair cells against the tectorial membrane. Figure 9-27 6 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Ear: Receptor Complexes External acoustic canal Cochlear branch of cranial nerve VIII Incus Oval window Malleus Stapes Vestibular duct (perilymph) Movement of sound waves Vestibular membrane Cochlear duct (endolymph) Basilar membrane Tympanic duct (perilymph) Tympanic membrane Round window Sound waves arrive at tympanic membrane. Movement of tympanic membrane causes displacement of the auditory ossicles. Movement of the stapes at the oval window establishes pressure waves in the perilymph of the vestibular duct. The pressure waves distort the basilar membrane on their way to the round window of the tympanic duct. Vibrations of the basilar membrane causes vibration of hair cells against the tectorial membrane. Information about the region and the intensity of stimulation is relayed to the CNS over the cochlear branch of cranial nerve VIII. The Ear: Receptor Complexes PLAY Figure 9-27 7 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Equilibrium and Hearing Auditory Pathways Hair cells excite sensory neurons Sensory neurons located in spiral ganglion Afferent axons form cochlear branch of vestibulocochlear nerve (CN VIII) Synapses in cochlear nucleus in medulla Neurons relay to midbrain Midbrain relays to thalamus Thalamus relays to auditory cortex (temporal lobe) in a frequency map Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Equilibrium and Hearing Pathways for Auditory Sensations Figure 9-28

Equilibrium and Hearing Key Note Balance and hearing both rely on hair cells. Which stimulus excites a particular group depends on the structure of the associated sense organ. In the semicircular ducts, fluid movement due to head rotation is sensed. In the utricle and saccule, shifts in the position of otoliths by gravity is sensed. In the cochlea, sound pressure waves distort the basilar membrane. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Aging and the Senses Impact of Aging on Sensory Ability Gradual reduction in smell and taste sensitivity as receptors are lost Lens changes lead to presbyopia (loss of near vision) Chance of cataract increases Progressive loss of hearing sensitivity as receptors are lost (presbycusis) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings