Hole’s Human Anatomy and Physiology Tenth Edition Shier  Butler  Lewis Chapter 12 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 12-1

Chapter 12 Somatic and Special Senses Sensory Receptors specialized cells or ____________ structures that collect information stimulate neurons to send impulses along sensory fibers to the brain 12-2

Receptor Types ___________________ respond to changes in chemical concentrations Pain receptors respond to tissue damage _________________ respond to changes in temperature Mechanoreceptors ________________________ Photoreceptors respond to light 12-3

Sensory Impulses stimulation of receptor causes local change in its membrane a graded electrical current is generated that reflects _________ of stimulation if receptor is part of a neuron, the membrane potential may generate an action potential if receptor is not part of a ________, the receptor potential must be transferred to a neuron to trigger an actin potential peripheral nerves transmit impulses to CNS ___________ feeling that occurs when brain interprets sensory impulse 12-4

Sensory Adaptation adjustment of sensory receptors from continuous stimulation stronger stimulus required to activate receptors ____________ undergo sensory adaptation 12-1

Somatic Senses senses associated with skin, muscles, joints, and viscera three groups ______________ senses – senses associated with body surface; touch, pressure, temperature, pain _______________ senses – senses associated with changes in muscles and tendons _________________ senses – senses associated with changes in viscera 12-6

Touch and Pressure Senses Free nerve endings common in epithelial tissues ___________ touch and pressure ______________________ abundant in hairless portions of skin detect light touch __________________ common in deeper subcutaneous tissues, tendons, and ligaments detect heavy pressure 12-7

Touch and Pressure Senses 12-8

Temperature Senses Warm receptors sensitive to temperatures above ____________ unresponsive to temperature above ______ (113 o F) ______________ sensitive to temperature between 10 o C (50 o F) and 20 o C (68 o F) Pain receptors ________________________________ respond to temperatures above 45 o C 12-9

Sense of Pain ______________________ widely distributed nervous tissue of brain lacks pain receptors stimulated by tissue damage, chemical, mechanical forces, or extremes in temperature ___________________ ______________ may exhibit referred pain _________________ 12-10

Referred Pain may occur due to sensory impulses from two regions following a common nerve pathway to brain 12-11

Pain Nerve Fibers ___________________ thin, myelinated conduct impulses rapidly associated with sharp pain well localized _________________ thin, unmyelinated conduct impulses more slowly associated with dull, aching pain ________________ 12-12

Regulation of Pain Impulses Thalamus allows person to be aware of pain Cerebral Cortex judges intensity of pain locates source or pain produces motor response to pain produces emotions to pain Pain Inhibiting Substances ___________ __________ ____________ 12-13

Stretch Receptors proprioceptors send information to CNS concerning lengths and tensions of muscles 2 main kinds of stretch receptors _________________ – in skeletal muscles ________________ – in tendons 12-14

Stretch Receptors 12-15

Special Senses sensory receptors are within large, complex sensory organs in the head _________ in olfactory organs _________ in taste buds ______________________ in ears sight in eyes 12-16

Smell Olfactory Receptors _________________ respond to chemicals dissolved in liquids _________________ contain olfactory receptors and supporting epithelial cells cover parts of nasal cavity, superior nasal conchae, and a portion of the nasal septum 12-17

Olfactory Receptors 12-18

Olfactory Nerve Pathways Once olfactory receptors are stimulated, nerve impulses travel through ________________ olfactory bulbs to _________________ limbic system (for emotions) and olfactory cortex (for interpretation) 12-19

Taste ________________ organs of taste located on papillae of tongue, roof of mouth, linings of cheeks and walls of pharynx _____________________ chemoreceptors taste cells – modified epithelial cells that function as receptors taste hairs –_________ that protrude from taste cells; sensitive parts of taste cells 12-20

Taste Receptors 12-21

Taste Sensations Four Primary Taste Sensations ________ – stimulated by carbohydrates sour – stimulated by acids _______ – stimulated by salts bitter – stimulated by many organic compound _________________________________ 12-22

Taste Nerve Pathways Sensory impulses from taste receptors travel along cranial nerves to _____________________ __________________ gustatory cortex (for interpretation) 12-23

Hearing Ear – organ of hearing 3 Sections ________ Middle ________ 12-24

External Ear _____________ collects sounds waves external auditory meatus lined with ceruminous glands carries sound to tympanic membrane _____________________ tympanic membrane tympanic membrane _________ in response to sound waves 12-25

Middle Ear tympanic cavity air-filled space in temporal bone auditory ossicles vibrate in response to tympanic membrane ________, ______, and stapes _____________ opening in wall of tympanic cavity stapes vibrates against it to move fluids in inner ear 12-26

Auditory Tube ________________ connects middle ear to throat helps maintain equal pressure on both sides of tympanic membrane usually closed by valve-like flaps in throat 12-27

Inner Ear complex system of labyrinths ____________________ bony canal in temporal bone filled with _________ membranous labyrinth tube within osseous labyrinth filled with ____________ 12-28

Inner Ear 3 Parts of Labyrinths ________ functions in hearing _________________ functions in equilibrium vestibule __________ in equilibrium 12-29

Cochlea ______________ upper compartment leads from oval window to apex of spiral part of bony labyrinth _____________ lower compartment extends from apex of the cochlea to ___________ part of bony labyrinth 12-30

Cochlea ______________ portion of membranous labyrinth in cochlea _________________ separates cochlear duct from scala vestibuli Basilar membrane separates cochlear duct from scala tympani 12-31

Organ of Corti group of hearing receptor cells (__________) on upper surface of basilar membrane different frequencies of vibration move different parts of basilar membrane particular sound frequencies cause hairs of receptor cells to bend nerve impulse generated 12-32

Organ of Corti 12-33

Auditory Nerve Pathways 12-34

Summary of the Generation of Sensory Impulses from the Ear 12-35

Equilibrium Static Equilibrium ____________ sense position of head when body is not moving _________________ semicircular canals sense rotation and movement of head and body 12-36

Vestibule ________ communicates with saccule and membranous portion of semicircular canals ________ communicates with cochlear duct ________ hair cells of utricle and saccule 12-37

Macula responds to changes in head position bending of hairs results in generation of nerve impulse 12-38

Semicircular Canals three canals at right angles __________ swelling of membranous labyrinth that communicates with the vestibule ______________ sensory organ of ampulla hair cells and supporting cells rapid turns of head or body stimulate hair cells 12-39

Crista Ampullaris 12-40

Sight ___________________ eyelids lacrimal apparatus extrinsic eye muscles 12-41

Eyelid _____________ composed of four layers skin muscle connective tissue conjunctiva _________________ - closes levator palperbrae superioris – opens ___________ – secrete oil onto eyelashes _____________ – mucous membrane; lines eyelid and covers portion of eyeball 12-42

Lacrimal Apparatus lacrimal gland lateral to eye secretes tears ___________ collect tears lacrimal sac collects from canaliculi ________________ collects from lacrimal sac empties tears into nasal cavity 12-43

Extrinsic Eye Muscles ______________ rotates eye up and medially _____________ rotates eye down and medially Medial rectus rotates eye medially 12-44

Extrinsic Eye Muscles Lateral rectus ________ eye laterally ______________ rotates eye down and laterally Inferior oblique rotates eye up and laterally 12-45

Structure of the Eye hollow spherical wall has 3 layers outer _____________ middle vascular tunic inner ____________ 12-46

Outer Tunic _________ anterior portion transparent light transmission light refraction Sclera posterior portion opaque ________ 12-47

Middle Tunic ______ anterior portion pigmented controls light intensity ____________ anterior portion pigmented holds lens moves lens for focusing Choroid coat provides blood supply pigments absorb extra light 12-48

Anterior Portion of Eye filled with ____________ 12-49

Lens transparent __________ ________________ largely composed of lens fibers elastic held in place by suspensory ligaments of ciliary body 12-50

Ciliary Body forms internal ring around front of eye ____________ – radiating folds _____________ – contract and relax to move lens 12-51

Accommodation ____________________________ 12-52

Iris composed of connective tissue and smooth muscle _______________ in iris dim light stimulates radial muscles and pupil dilates bright light stimulates circular muscles and pupil constricts 12-53

Aqueous Humor ________________________ secreted by epithelium on inner surface of the ciliary body provides nutrients maintains shape of anterior portion of eye _____________________________ 12-54

Inner Tunic _________ contains visual receptors continuous with optic nerve ends just behind margin of the ciliary body composed of several layers ____________ – yellowish spot in retina ______________ – center of macula lutea; produces sharpest vision optic disc – blind spot; contains no visual receptors ________________ – thick gel that holds retina flat against choroid coat 12-55

Layers of Retina ________________________________, and ganglion cells - provide pathway for impulses triggered by photoreceptors to reach the optic nerve _______________________________ – modify impulses 12-56

Light Refraction Refraction __________________ occurs when light waves pass at an oblique angle into mediums of different densities 12-57

Types of Lenses _________ lenses cause light waves to _________ _______ lenses cause light waves to _______ 12-58

Focusing On Retina as light enters eye, it is refracted by convex surface of cornea _______________________ image focused on retina is upside down and reversed from left to right 12-59

Visual Receptors Rods ______________ contain light sensitive pigment called rhodopsin hundred times more sensitive to light than cones _____________________ produce colorless vision produce outlines of objects Cones short, blunt projections contain light sensitive pigments called erythrolabe, chlorolabe, and cyanolabe provide vision in bright light produce sharp images produce color vision 12-60

Rods 12-61

Visual Pigments _____________ light-sensitive pigment in rods decomposes in presence of light triggers a complex series of reactions that initiate nerve impulses impulses travel along optic nerve Pigments on Cones each set contains different light- sensitive pigment each set is sensitive to different wavelengths color perceived depends on which sets of cones are stimulated ________ – responds to red _______ – responds to green ________ – responds to blue 12-62

Stereoscopic Vision __________________________________ results from formation of two slightly different retinal images 12-63

Visual Pathway 12-64

Life-Span Changes Age related hearing loss due to ___________________________________ degeneration of nerve pathways to the brain tinnitus Age-related visual problems include __________ floaters (crystals in vitreous humor) loss of elasticity of lens glaucoma ___________ macular degeneration 12-65

Clinical Application Refraction Disorders ___________________ nearsightedness ______________ farsightedness 12-66