Slides 1 to 106 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The General Senses Sensory Basics Sensory receptors—Specialized cells or cell processes that monitor external or internal conditions. Simplest are free nerve endings. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The General Senses More Sensory Basics Receptive field—The area monitored by a single receptor cell Adaptation—Reduction in sensitivity at a receptor or along a sensory pathway in the presence of a constant stimulus. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Receptors and Receptive Fields The General Senses Receptors and Receptive Fields Figure 9-1

The General Senses General versus Special Senses General senses—Temperature, pain, touch, pressure, vibration, and proprioception. Receptors throughout the body Special senses—Smell, taste, vision, balance, and hearing. Receptors located in sense organs (e.g., ear, eye). Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The General Senses Key Note Stimulation of a receptor produces action potentials that propagate along the axon of a sensory neuron. The frequency or pattern of action potentials contains information about the stimulus. A person’s perception of the nature of that stimulus depends on the path it takes inside the CNS. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The General Senses Pain Definitions Nociceptors—Receptors for tissue damage to lead to the sensation of pain Referred pain—Perception of pain in a part of the body not actually stimulated Fast (prickling) pain—Localized pain carried quickly to the CNS on myelinated axons Slow (burning) pain—Generalized pain carried on slow unmyelinated axons Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The General Senses Referred Pain Figure 9-2

The General Senses Temperature Thermoreceptors detect temperature change Free nerve endings Found in dermis, skeletal muscle, liver, hypothalamus Fast adapting Cold receptors greatly outnumber warm receptors Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The General Senses Touch, Pressure, and Position Mechanoreceptors—Receptors that respond to physical distortion of their cell membranes. Tactile receptors—Sense touch, pressure, or vibration Baroreceptors—Sense pressure changes in walls of blood vessels, digestive organs, bladder, lungs Proprioceptors—Respond to positions of joints and muscle Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The General Senses Tactile Receptors Fine touch or pressure receptors Highly detailed information about a stimulus Crude touch or pressure receptors Poorly localized information about a stimulus Important types: root hair plexus, tactile disks, tactile corpuscles, lamellated corpuscles, Ruffini corpuscles Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Tactile Receptors in the Skin The General Senses Tactile Receptors in the Skin Figure 9-3

The General Senses Baroreceptors Provide pressure information essential for autonomic regulation Arterial blood pressure Lung inflation Digestive coordination Bladder fullness Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Baroreceptors and the Regulation of Autonomic Functions The General Senses Baroreceptors and the Regulation of Autonomic Functions Figure 9-4

The General Senses Proprioceptors Monitor joint angle, tension in tendons and ligaments, state of muscular contraction Include: Muscle spindles Golgi tendon organs Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The General Senses Chemical Detection Chemoreceptors respond to chemicals dissolved in body fluids that surround them and monitor the chemical composition of blood and tissues Chemicals that can be sensed include: Carbon dioxide Oxygen Hydrogen ion Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Locations and Functions of Chemoreceptors The General Senses Locations and Functions of Chemoreceptors Figure 9-5

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—Smell The Olfactory Pathways Axons from olfactory receptors penetrate cribriform plate of ethmoid bone Synapse in olfactory bulb Olfactory tract projects to: Olfactory cerebral cortex Hypothalamus Limbic System Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

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—Taste Gustatory Receptors Figure 9-7(c)

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 Accessory Structures of the Eye Figure 9-8(a)

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 Lacrimal Apparatus of the Eye Figure 9-8(b)

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

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 (Tunics) 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(b)

The Special Senses—Vision Layers of the Eye Fibrous tunic Sclera Dense fibrous connective tissue “White of the eye” Cornea Transparent Light entrance PLAY The Eye: Light Path 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 The Sectional Anatomy of the Eye Figure 9-10 (c)

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 Organization of the Retina Photoreceptor layer Bipolar cells Amacrine, horizontal cells modify signals Ganglion cells Optic nerve (II) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

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

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 Special Senses—Vision Chambers of the Eye Two cavities (Anterior & Posterior) Ciliary body, lens between the two Anterior cavity Anterior compartment Between cornea and iris Aqueous humor Posterior compartment Between iris and lens Posterior cavity Vitreous body Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

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 (curvature) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses - Vision Focal Point: The point on the lens where nearly parallel lines of light pass through Focal Distance: how strongly light diverges or converges Visual Accomodation: measure of lens curvature

The Special Senses—Vision Focal Point, Focal Distance, and Visual Accommodation Figure 9-15(d)

The Special Senses—Vision Focal Point, Focal Distance, and Visual Accommodation Figure 9-15(e)

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

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

The Special Senses—Vision Visual Abnormalities (Normal vision) Figure 9-17(a)

The Special Senses—Vision Visual Abnormalities (Nearsightedness) Figure 9-17(b)

Myopia

The Special Senses—Vision Visual Abnormalities Figure 9-17(c)

The Special Senses—Vision Visual Abnormalities (Farsightedness) Figure 9-17(d)

Hyperopia

The Special Senses—Vision Visual Abnormalities Figure 9-17(e)

Color blindness Color vision deficiency, is the inability to perceive differences between some of the colors that others can distinguish. It is most often of genetic nature, but may also occur because of eye, nerve, or brain damage, or exposure to certain chemicals.

Example of an Ishihara color test plates.

Color Vision The colors of the rainbow as viewed by a person with no color vision deficiencies. The colors of the rainbow as viewed by a person with protanopia – affects red receptors The colors of the rainbow as viewed by a person with deuteranopia – affects green receptors The colors of the rainbow as viewed by a person with tritanopia – affects blue- yellow receptors

The Special Senses—Vision Key Note Light passes through the cornea, crosses the anterior cavity to the lens, moves through 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 Photoreceptor Anatomy Outer segment Discs with visual pigments Light absorption by rhodopsin Opsin + retinal Inner segment Synapse with bipolar cell Control of neurotransmitter release Effect on bipolar cells Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

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

Photon Retinal changes shape Retinal and opsin are reassembled to form rhodopsin Bleaching (separation) Regeneration enzyme Retinal restored ADP ATP Opsin Opsin Opsin inactivated Figure 9-20 1 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Retinal and opsin are reassembled to form rhodopsin Figure 9-20 2 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Photon Retinal and opsin are reassembled to form rhodopsin Figure 9-20 3 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Photon Retinal and opsin are reassembled to form rhodopsin Retinal changes shape Retinal and opsin are reassembled to form rhodopsin Figure 9-20 4 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Photon Retinal changes shape Retinal and opsin are reassembled to form rhodopsin Bleaching (separation) enzyme Retinal restored ADP ATP Figure 9-20 5 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Photon Retinal changes shape Retinal and opsin are reassembled to form rhodopsin Bleaching (separation) enzyme Retinal restored ADP ATP Opsin Opsin Opsin inactivated Figure 9-20 6 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Photon Retinal changes shape Retinal and opsin are reassembled to form rhodopsin Bleaching (separation) Regeneration enzyme Retinal restored ADP ATP Opsin Opsin Opsin inactivated Figure 9-20 7 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Vision The Visual Pathway Ganglion cells axon converge at optic disc Axons leave as optic nerve (II) Some axons cross at optic chiasm Synapse in thalamus bilaterally Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Special Senses—Vision The Visual Pathway Thalamic neurons project to visual cortex Located in occipital lobes Contains map of visual field Visual inputs to hypothalamus and pineal gland establish daily circadian rhythms Affecting metabolic rate, endocrine function, blood pressure, digestive activities, awake-sleep cycle and other processes Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

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

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 The Anatomy of the Ear Figure 9-22

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 (Eustachian tube) Connection to nasopharynx Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

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

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

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

Equilibrium and Hearing The Anatomy of the Ear Figure 9-24(c) PLAY The Ear: Ear Anatomy

Equilibrium and Hearing Semicircular ducts Connect to utricle Contains ampulla with hair cells Stereocilia contact cupola Gelatinous mass distorted by fluid movement Detects rotation of head in three planes Anterior, posterior, lateral ducts Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Equilibrium and Hearing Equilibrium (continued) Saccule and utricle Hair cells cluster in maculae Stereocilia contact otoliths (heavy mineral crystals) Gravity pulls otoliths Detect tilt of head Sensory axons in vestibular branch of CN VIII Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

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 Head tilted posteriorly Gravity Otolith moves “downhill,” distorting hair cell processes Receptor output increases Figure 9-25(e) 1 of 4 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

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 PLAY The Ear: Balance Figure 9-25(e) 4 of 4 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Vestibular System

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. PLAY The Ear: Receptor Complexes 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