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

2. 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

3. 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

4. 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

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

6. 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

7. 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

8. The General Senses
Referred Pain
Figure 9-2

9. 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

10. 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

11. 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

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

13. 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

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

15. 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

16. 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

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

18. 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

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

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

21. 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

22. 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

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

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

25. The Special Senses—Taste
Gustatory Receptors
Figure 9-7(c)

26. 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

27. 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

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

29. 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

30. The Special Senses—Vision
The Lacrimal Apparatus of the Eye
Figure 9-8(b)

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

32. 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

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

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

35. 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

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

37. 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

38. 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

39. 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

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

41. 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

42. 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

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

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

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

46. 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

47. 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

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

49. 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

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

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

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

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

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

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

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

57. The Special Senses—Vision
Visual Abnormalities
Figure 9-17(a)

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

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

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

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

62. 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

63. 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

64. 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

65. 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

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

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

68. 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

69. 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

70. 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

71. 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

72. 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
Thalamic neurons project to visual cortex
Located in occipital lobes
Contains map of visual field
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

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

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

75. 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

76. 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

77. 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

78. 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

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

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

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

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

83. 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

84. 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

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

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

87. 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

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

89. 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

90. 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

91. 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

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

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

94. 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

95. 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

96. 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

97. 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

98. 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

99. 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

100. 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

101. 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

102. Equilibrium and Hearing
Pathways for Auditory Sensations
Figure 9-28

103. 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

104. 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