1. Chapter 9
Sensory Systems

2. Announcements Chapter 8a- Extra credit (10 pts)
Chapter 8 online quiz- Due Wednesday!
Quiz 7 Wednesday- Chapters 8, 9
Midterm grades updated

3. Chapter Outline Kinds of Sensory receptors Vision and the eye
Hearing, balance, and the ear
Smell and taste

4. A) Parasympathetic impulses were increased.
Perry joined the National Guard and was sent overseas to a war zone. While on duty, an improvised explosive device went off near him and he barely escaped unharmed. What would be true of his nervous system?
A) Parasympathetic impulses were increased.
B) Most sympathetic impulses were reduced.
C) The sympathetic neurons all released acetylcholine.
D) Norepinephrine and epinephrine were released.

5. Sensory System
Sensory receptors generate electrochemical messages in response to stimuli
Receptors are classified by the type of stimulus to which they respond
Receptors for the general senses are distributed throughout the body
Vision depends on the eye
Hearing depends on the ear

6. Sensory Receptors Generate Electrochemical Messages
Sensory receptors respond to stimuli by generating electrochemical messages
All sensory receptors are selective, responding best to one form of energy

7. Sensory Receptors Generate Electrochemical Messages
Step 1: A sensory
receptor detects the
stimulus from the
external or internal
environment.
Stimulus
Sensory
receptor
Step 2: Sensory
neurons conduct a
nerve impulse to
the spinal cord and
then to the brain, or
directly to the brain.
Nerve impulse carried
by sensory nerves
Step 3: The brain
interprets the
information from the
sensory receptor.
Spinal cord
Brain
Step 4: The brain’s
interpretation of the
information is a
perception or
understanding of
the stimulus.
Figure 9.1

8. Sensory Receptors
Continuous stimulation leads to sensory adaptation, a decrease in the awareness of the stimuli

9. Receptor Classification
The body contains many specialized receptors including
Mechanoreceptors
Thermoreceptors
Photoreceptors
Chemoreceptors
Pain receptors

10. Receptor Classification
Receptors for the general senses are located throughout the body

11. Receptor Classification
Receptors rely on either free nerve endings or encapsulated nerve endings
Free nerve endings are the tips of dendrites of sensory neurons
Encapsulated nerve endings are those in which a connective tissue capsule encloses and protects the tips of dendrites of sensory neurons

12. Receptor Classification
Figure 9.2 (1 of 2)

13. Receptor Classification
Figure 9.2 (2 of 2)a

14. Receptor Classification
Figure 9.2 (2 of 2)b

15. Receptor Classification
The special senses
Vision
Hearing
Equilibrium
Smell
Taste

16. Receptors for the General Senses
Mechanoreceptors located in the skin perceive touch and pressure

17. Receptors for the General Senses
Free nerve endings in Merkel disks receive touch, as do the encapsulated nerve endings in Meissner’s corpuscles

18. Receptors for the General Senses
Figure 9.2 (2 of 2)c

19. Receptors for the General Senses
Figure 9.2 (2 of 2)d

20. Receptors for the General Senses
Pacinian corpuscles
Respond to pressure when it is first applied
Ruffini corpuscles
Respond to continuous pressure

21. Receptors for the General Senses
Figure 9.2 (2 of 2)e

22. Receptors for the General Senses
Figure 9.2 (2 of 2)f

23. Receptors for the General Senses
Body and limb position are detected by
Muscle spindles responding to the stretch of a muscle
Golgi tendon organs measuring muscle tension

24. Receptors for the General Senses
Pain receptors are found in all tissues of the body
Referred pain
Pain felt somewhere besides the site of the injury
Common with damage to internal organs

25. Receptors for the General Senses
Lungs and
diaphragm
Heart
Stomach
Liver and
gallbladder
Small intestine
Appendix
Colon
Urinary
bladder
Ureter
Testes
Kidney
Figure 9.3

26. Vision Depends on the Eye
The outer layer of the eye is made of
The sclera
Protects and shapes the eye
Provides attachment for muscles
The cornea
Allows light to enter

27. Vision Depends on the Eye
Table 9.1 (2 of 4)

28. Vision Depends on the Eye
Table 9.1 (3 of 4)

29. Vision Depends on the Eye
Table 9.1 (4 of 4)

30. Vision Depends on the Eye
Optic nerve
Optic disk
(blind spot)
Fovea
Sclera
Choroid
Retina
Vitreous humor
(fills the posterior
chamber)
Lens
Ciliary body
Aqueous humor
(fills the anterior
chamber)
Cornea
Pupil
Iris
Sclera
Figure 9.4

31. Vision Depends on the Eye
The choroid, ciliary body, and iris make up the middle layer
The middle layer is vascular

32. Vision Depends on the Eye
The pupil
An opening in the center of the iris
Allows light to enter the eye and reach the innermost layer, the retina, which contains
Photoreceptors
Rods
Cones

33. Vision Depends on the Eye
The cones are concentrated in the center of the retina (fovea) for focused vision

34. Vision Depends on the Eye
The optic nerve
Cranial nerve II
Carries visual information to the brain
Forms a blind spot where it leaves the retina
An image that strikes the blind spot can not be seen

35. Vision Depends on the Eye
The eyeball is divided into two fluid filled cavities
The posterior cavity
The main cavity of the eye
Contains vitreous humor, the jelly–like fluid
The anterior cavity
The cavity in front of the eye between the cornea and the lens
Contains aqueous humor, the watery fluid

36. Vision Depends on the Eye
Glaucoma
Results when pressure of the aqueous humor reaches dangerous levels due to underabsorption or over–secretion of the fluid

37. Vision Depends on the Eye
Light is bent (refracted) at 4 points when it enters the eye
The cornea
The aqueous humor
The lens
The vitreous humor

38. Vision Depends on the Eye
The ciliary muscle can change the shape of the lens, allowing the image to be focused on the retina
The elasticity of the lens provides for the process of accommodation
The changing the shape of the lens to change the bending of light

39. Vision Depends on the Eye
Figure 9.5

40. Vision Depends on the Eye
A cataract
A lens that has become cloudy, usually due to aging

41. Vision Depends on the Eye
Depth perception and a focused image are accomplished by convergence
Keeps both eyes focused on the midline of an object

42. Vision Depends on the Eye
Farsightedness, nearsightedness, and astigmatism are the three most common visual problems and are due to refractive problems
These refractive disorders may be caused by discrepancies in the lens or the shape of the eye
Normal vision can be restored with corrective lenses

43. Vision Depends on the Eye
Table 9.2

44. Vision Depends on the Eye
Figure 9.6a

45. Vision Depends on the Eye
Figure 9.6b

46. Vision Depends on the Eye
Figure 9.6c

47. Vision Depends on the Eye
Figure 9.6d

48. Vision Depends on the Eye
Rods and cones are the two types of photoreceptors
All photoreceptors respond to light with a neural message sent to the brain

49. Vision Depends on the Eye
Figure 9.7

50. Vision Depends on the Eye
Light
Choroid
Sclera
Retina
Blind spot
(a) Light enters the left eye
and strikes the retina.
Figure 9.8a

51. Vision Depends on the Eye
Light
Vitreous
humor
Ganglion
cell layer
Electrical
signals
Bipolar
cell layer
Retina
Cone
Photoreceptor
cells
Rod
Pigment layer
Axons
Choroid
Sclera
(b) When light is focused on the retina, it passes through the ganglion
cell layer and bipolar cell layer before reaching the rods and
cones. In response to light, the rods and cones generate electrical
signals that are sent to bipolar cells and then to ganglion cells.
These cells begin the processing of visual information.
Figure 9.8b

52. Vision Depends on the Eye
Light
Retina
Optic nerve
Visual cortex
(c) The axons of the ganglion cells leave the eye at the blind spot,
carrying nerve impulses to the brain (viewed from below) by means
of the optic nerve.
Figure 9.8c

53. Vision Depends on the Eye
Rods allow us to see in dim light, seeing black and white
They contain the pigment rhodopsin, which is broken down in bright light
They are more numerous than cones

54. Vision Depends on the Eye
Color vision depends on cones
Three types of cones—red, blue, and green—allow us to see color
Produce sharp images
A reduced number or lack of one of the types of cones results in color blindness

55. Vision Depends on the Eye
Figure 9.9

56. Vision Depends on the Eye
Cones function in
color vision.
Rods function in
black-and-white vision.
Disks containing
visual pigments
Rod cell
Cone cell
Nuclei
Synaptic
endings
Figure 9.9 (1 of 2)

57. Vision Depends on the Eye
Rod cell
Cone cell
Figure 9.9 (2 of 2)

58. Hearing Depends on the Ear
In order to hear, the ear collects and amplifies sound waves
Converts them to neural messages
The sound waves are produced by vibrations

59. Hearing Depends on the Ear
Figure 9.11a

60. Hearing Depends on the Ear
Figure 9.11b

61. Hearing Depends on the Ear
Figure 9.11c

62. Hearing Depends on the Ear
Three divisions of the ear
Outer ear
The middle ear
The inner ear

63. Hearing Depends on the Ear
Outer ear
The receiver
Consists of the pinna and external auditory canal
Receives the waves
The middle ear
The amplifier
The inner ear
The transmitter

64. Hearing Depends on the Ear
Outer
ear
(receiver)
Middle
ear
(amplifier)
Inner
ear
(transmitter)
Figure 9.12 (1 of 2)

65. Hearing Depends on the Ear
Outer ear
(receiver)
Middle ear
(amplifier)
Inner ear
(transmitter)
Eardrum
(tympanic membrane)
Malleus
(hammer)
Incus
(anvil)
Stapes
(stirrup)
Vestibular apparatus:
Semicircular canals
Vestibule
Auditory nerve
Oval window
Cochlea
Round window
External auditory canal
Auditory tube
(Eustachian
tube)
The pinna gathers sound and
funnels it into the external
auditory canal to the tympanic
membrane (eardrum).
The eardrum vibrates
synchronously with sound
waves, causing the bones
of the middle ear to move.
The three bones of the middle
ear amplify the pressure waves
and convey the vibrations of
the eardrum to the inner ear.
The cochlea converts pressure
waves to neural messages that
are sent to the brain for
interpretation as sound.
Figure 9.12 (2 of 2)

66. Hearing Depends on the Ear
Table 9.3 (1 of 2)

67. Hearing Depends on the Ear
Table 9.3 (2 of 2)

68. Hearing Depends on the Ear
The tympanic membrane separates the outer ear from the middle ear
The middle ear consists of an air-filled cavity within the temporal bone of the skull and the three auditory bones
Malleus
Incus
Stapes

69. Hearing Depends on the Ear
The middle ear
Takes sound from the eardrum to the oval window
Uses the malleus, incus, and stapes to amplify the sound

70. Hearing Depends on the Ear
The inner ear
A transmitter
Consists of the cochlea and vestibular apparatus
The spiral organ is most directly responsible for the sense of hearing

71. Hearing Depends on the Ear
Figure 9.13 (1 of 2)

72. Hearing Depends on the Ear
Tectorial
membrane
Hair cell
Figure 9.13 (2 of 2)

73. Hearing Depends on the Ear
Vibrations
Transmitted from the middle ear to the fluid within the cochlea
Activate hair cells that stimulate the nerves that carry the impulse to the brain
The more hair cells stimulated, the louder the sound

74. Hearing Depends on the Ear
Figure 9.11a

75. Hearing Depends on the Ear
Figure 9.11b

76. Hearing Depends on the Ear
Figure 9.14

77. Hearing Depends on the Ear
Round
window
Upper compartment
(vestibular canal)
Cochlea
Oval
window
Central compartment
(cochlear duct)
Stapes
(stirrup)
Incus
(anvil)
Malleus
(hammer)
Spiral organ (of Corti)
Eardrum
(tympanic
membrane)
Tectorial membrane
Hair cell
Sound waves
Basilar membrane
Step 1: Sound waves cause
the eardrum to vibrate. These
vibrations are transmitted
through the bones of the
middle ear to the oval window.
Lower compartment
(tympanic canal)
Step 2: Movement of the oval
window creates pressure waves
in the cochlear fluid, causing the
basilar membrane to vibrate.
Auditory
tube
Figure 9.14 (1 of 2)

78. Hearing Depends on the Ear
Upper compartment
(vestibular canal)
Central compartment
(cochlear duct)
Spiral organ (of Corti)
Tectorial membrane
Hair cell
Basilar membrane
Lower compartment
(tympanic canal)
Step 3: When the basilar membrane
vibrates, the hairlike projections on the
hair cell receptors are pushed against the
overhanging tectorial membrane,
resulting in nerve impulses that are
carried to the brain by the auditory nerve.
Figure 9.14 (2 of 2)

79. Hearing Depends on the Ear
Pitch is interpreted by the frequency of impulses in the auditory nerve
Figure 9.11c

80. Hearing Depends on the Ear
There are two types of hearing loss
Conductive
Involves an obstruction along the route that sound follows to the inner ear
Sensorineural
Caused by damage to the hair cells or the nerve supply of the inner ear

81. Balance Depends on the Vestibular Apparatus
Depends on the vestibular apparatus of the inner ear
A fluid-filled maze of chambers and canals within the inner ear

82. Balance Depends on the Vestibular Apparatus
Dynamic equilibrium
Bony labyrinth
Ampulla
Utricle
Saccule
Semicircular
canals
Cochlea
Cochlear duct
Figure 9.16

83. Balance Depends on the Vestibular Apparatus
Figure 9.16a (1 of 2)

84. Balance Depends on the Vestibular Apparatus
Figure 9.16a (2 of 2)

85. Balance Depends on the Vestibular Apparatus
Figure 9.16b (1 of 2)

86. Balance Depends on the Vestibular Apparatus
Figure 9.16b (2 of 2)

87. Balance
The semicircular canals and the vestibule make up the vestibular apparatus

88. Balance The semicircular canals The vestibule
Contain sensory receptors that monitor movement
The vestibule
Monitors balance when we are not moving

89. Smell and Taste Are the Chemical Senses
Olfactory receptors
Neurons with long cilia covered by mucus
Located in the roof of the nasal cavity
There are about 1000 types of olfactory receptors

90. Smell and Taste Are the Chemical Senses
Figure 9.17

91. Smell and Taste Odor molecules
Dissolve in the mucus and bind to the receptors
Causes a stimulation that is relayed to the olfactory bulb in the brain

92. Smell and Taste Taste Perceived by taste buds
Located on the tongue and inner surfaces of the mouth

93. Smell and Taste
Figure 9.18

94. Smell and Taste
Figure 9.18a–b

95. Smell and Taste
Figure 9.18b–c

96. Smell and Taste
Figure 9.18d

97. Smell and Taste Taste cells have taste hairs
They project into a pore at the tip of the taste bud
When food molecules are dissolved in water, they enter the pore and stimulate the taste hairs

98. Smell and Taste Taste buds sense the five basic tastes Sweet Salty
Sour
Bitter
Umami