Chapter 10:
The Sensory System
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Taylor: Memmler’s Structure and function of the Human Body
Overview
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Taylor: Memmler’s Structure and function of the Human Body
Key Terms
accommodation
gustation
retina
adaptation
iris
sclera
auditory tube
lacrimal apparatus
semicircular canal
aqueous humor
lens (crystalline lens)
sensory adaptation
choroid
macula
sensory receptor
cochlea
olfaction
spiral organ
conjunctiva
ossicle
tympanic membrane
convergence
proprioceptor
vestibule
cornea
refraction
vitreous body
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Taylor: Memmler’s Structure and function of the Human Body
The Senses
Learning Outcomes
1. Describe the function of the
sensory system.
2. Differentiate between the different
types of sensory receptors and
give examples of each.
3. Describe sensory adaptation and
explain its value.
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Taylor: Memmler’s Structure and function of the Human Body
The Senses
• Sensory system detects environmental change
– Environmental change initiates nerve impulse
(stimulus)
– Stimulus interpreted by cerebral cortex
– Sensation experienced
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Taylor: Memmler’s Structure and function of the Human Body
The Senses
Sensory Receptors
• Receptor classification based on structure
– Free dendrite
– End-organ
– Specialized cell
• Receptor classification based on stimulus
– Chemoreceptor
– Photoreceptor
– Thermoreceptor
– Mechanoreceptor
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Taylor: Memmler’s Structure and function of the Human Body
The Senses
Special and General Senses
Special Senses
General Senses
Vision
Pressure
Hearing
Temperature
Equilibrium
Pain
Taste
Touch
Smell
Sense of position
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Taylor: Memmler’s Structure and function of the Human Body
The Senses
Sensory Adaptation
• Receptors often become less sensitive to a continuous
unimportant stimulus.
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Taylor: Memmler’s Structure and function of the Human Body
The Senses
Checkpoints
10-1 What is a sensory receptor?
10-2 What are some categories of sensory receptors
based on type of stimulus?
10-3 How do the special and general senses differ in
location?
10-4 What happens when a sensory receptor adapts to a
stimulus?
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Taylor: Memmler’s Structure and function of the Human Body
The Senses
Pop Quiz
10.1
Which of the following is a special sense?
A) Pressure
B) Taste
C) Touch
D) Proprioception
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Taylor: Memmler’s Structure and function of the Human Body
The Senses
Pop Quiz Answer
10.1
Which of the following is a special sense?
A) Pressure
B) Taste
C) Touch
D) Proprioception
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Taylor: Memmler’s Structure and function of the Human Body
The Eye and Vision
Learning Outcomes
4. List and describe the structures
that protect the eye.
5. Identify the three tunics of the
eye.
6. Define refraction and list the
refractive parts of the eye.
7. Differentiate between the rods and
the cones of the eye.
8. Compare the functions of the
extrinsic and intrinsic eye muscles.
9. Describe the nerve supply to the
eye
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Taylor: Memmler’s Structure and function of the Human Body
The Eye and Vision
Protective Structures of the Eye
• Bony orbit
• Eyelids
• Eyelashes
• Eyebrows
• Conjunctiva
• Lacrimal glands
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-1 The eye’s protective structures.
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-2 The lacrimal apparatus.
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Taylor: Memmler’s Structure and function of the Human Body
The Eye and vision
Structure of the Eyeball
• Eyeball has three separate coats (tunics)
Fibrous Tunic
Vascular Tunic
Nervous Tunic (retina)
Sclera
Choroid
Rods
Cornea
Ciliary muscle
Cones
Suspensory ligaments
Iris
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-3
The eye.
What anterior structure is
continuous with the sclera?
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Taylor: Memmler’s Structure and function of the Human Body
The Eye and Vision
Pathway of Light Rays and Refraction
• Transparent parts of the eye that refract light
–
Cornea
–
Aqueous humor
–
Crystalline lens
–
Vitreous body
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Taylor: Memmler’s Structure and function of the Human Body
The Eye and Vision
Function of the Retina
• Rod cells
– Function in dim light
– Shades of gray
– Blurred images
• Cone cells
– Function in bright light
– Color sensitive
– Sharp images
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-4
Structure of
the retina.
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-5 The fundus (back) of the eye as seen through an
ophthalmoscope.
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Taylor: Memmler’s Structure and function of the Human Body
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Taylor: Memmler’s Structure and function of the Human Body
The Eye and Vision
Checkpoints
10-5
What are some structures that protect the eye?
10-6
What are the components of the three tunics of
the eyeball?
10-7
What are the structures that refract light as it
passes through the eye?
10-8
What are the receptor cells of the retina?
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Taylor: Memmler’s Structure and function of the Human Body
The Eye and Vision
Pop Quiz
10.2
The middle, pigmented layer of the eye is the
A) Sclera
B) Conjunctiva
C) Retina
D) Choroid
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Taylor: Memmler’s Structure and function of the Human Body
The Eye and Vision
Pop Quiz Answer
10.2
The middle, pigmented layer of the eye is the
A) Sclera
B) Conjunctiva
C) Retina
D) Choroid
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Taylor: Memmler’s Structure and function of the Human Body
The Eye and Vision
Muscles of the Eye
• Adjust eye so retina receives clear image
– Extrinsic muscles
• Outer surface of eyeball
• Voluntary
• Control convergence for three-dimensional vision
– Intrinsic muscle
• Within eyeball
• Iris regulates amount of light entering eye
• Ciliary muscle shapes lens for near and far vision
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-6 Extrinsic muscles of the eye.
What characteristics are used in naming the extrinsic eye muscles?
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-7 Function of the iris.
What muscles of the iris contract to make the pupil smaller? Larger?
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-8 The ciliary muscle and lens (posterior view).
What structures hold the lens in place?
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-9 Accommodation for near vision.
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Taylor: Memmler’s Structure and function of the Human Body
The Eye and Vision
Nerve Supply to the Eye
• Sensory
– Optic nerve (CN II)
– Ophthalmic branch of trigeminal nerve (CN V)
• Motor
– Oculomotor nerve (CN III)
– Trochlear (CN IV)
– Abducens (CN VI)
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-10 Nerves of the eye.
Which of the
nerves shown
controls eye
movement?
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Taylor: Memmler’s Structure and function of the Human Body
The Eye and Vision
Checkpoints
10-9
What is the function of the extrinsic eye muscles?
10-10
What is the function of the iris?
10-11
What is the function of the ciliary muscle?
10-12
What is cranial nerve II and what does it do?
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Taylor: Memmler’s Structure and function of the Human Body
The Eye and Vision
Pop Quiz
10.3
Which of the following is an intrinsic eye muscle?
A) Iris
B) Lateral rectus
C) Superior rectus
D) Suspensory ligament
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Taylor: Memmler’s Structure and function of the Human Body
The Eye and Vision
Pop Quiz Answer
10.3
Which of the following is an intrinsic eye muscle?
A) Iris
B) Lateral rectus
C) Superior rectus
D) Suspensory ligament
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Taylor: Memmler’s Structure and function of the Human Body
The Ear
Learning Outcomes
10. Describe the three divisions of
the ear.
11. Describe the receptor for hearing
and explain how it functions.
12. Compare the location and
function of the equilibrium
receptors.
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Taylor: Memmler’s Structure and function of the Human Body
The Ear
• Sense organ for hearing and equilibrium
• Components
– Outer ear
– Middle ear
– Inner ear
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Taylor: Memmler’s Structure and function of the Human Body
The Ear
The Outer Ear
• Structure
– Pinna
– External auditory canal
– Ceruminous glands
– Tympanic membrane
• Function
– Collect sound waves and transmit sounds to middle
ear
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-11 The ear.
What structure separates the outer ear from the middle ear?
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Taylor: Memmler’s Structure and function of the Human Body
The Ear
Middle Ear
• Structure
– Ear ossicles
• Malleus
• Incus
• Stapes
– Auditory tube
• Function
– Amplifies sound waves and transmit sounds to inner
ear
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-11 The ear.
What structure separates the outer ear from the middle ear?
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Taylor: Memmler’s Structure and function of the Human Body
The Ear
Inner Ear
• Structure
– Bony labyrinth; contains perilymph
• Divisions
• Vestibule
• Semicircular canals
• Cochlea
– Membranous labyrinth; contains endolymph
• Function
– Transduce sound waves into nerve impulses
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-12 The ear.
What nerve is formed by the merger of the nerves from the inner ear?
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-13 Cochlea and
the spiral organ.
Which part of the cochlea
contains the spiral organ?
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Taylor: Memmler’s Structure and function of the Human Body
The Ear
The Steps in Hearing
1. Sound waves enter external auditory canal
2. Tympanic membrane vibrates
3. Ossicles transmit vibrations across middle ear
4. Stapes transmits vibrations at oval window to inner ear
fluid
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Taylor: Memmler’s Structure and function of the Human Body
The Ear
The Steps in Hearing (continued)
5.Vibrations travel through perilymph of bony labyrinth
6.Spiral organ’s hair cells vibrate against tectorial
membrane, generating nerve impulses
7.Impulses travel via cochlear nerve to temporal lobe
cortex, where they are interpreted
8.Sound waves leave inner ear through the round window
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Taylor: Memmler’s Structure and function of the Human Body
The Steps in Hearing
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Taylor: Memmler’s Structure and function of the Human Body
The Ear
Equilibrium
• Ciliated equilibrium sensory receptors are located in
vestibule and semicircular canals.
• Types of Receptors
• Maculae
• Cristae
• Nerve supply via vestibular nerve
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-14 Action of the vestibular equilibrium receptors
(maculae).
What happens
to the cilia of
the macular
cells when the
fluid around
them moves?
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-15
Action of the
equilibrium receptors
(cristae) in the
semicircular canals.
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Taylor: Memmler’s Structure and function of the Human Body
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Taylor: Memmler’s Structure and function of the Human Body
The Ear
Checkpoints
10-13
What are the ossicles of the ear and what do
they do?
10-14
What is the name of the organ of hearing and
where is it located?
10-15
Where are the receptors for equilibrium located?
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Taylor: Memmler’s Structure and function of the Human Body
The Ear
Pop Quiz
10.4
The ear ossicle that is in contact with the tympanic
membrane is the
A) Malleus
B) Incus
C) Meatus
D) Stapes
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Taylor: Memmler’s Structure and function of the Human Body
The Ear
Pop Quiz Answer
10.4
The ear ossicle that is in contact with the tympanic
membrane is the
A) Malleus
B) Incus
C) Meatus
D) Stapes
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Taylor: Memmler’s Structure and function of the Human Body
Other Special Sense Organs
Learning Outcome
13. Discuss the location and function
of the special sense organs for
taste and smell.
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Taylor: Memmler’s Structure and function of the Human Body
Other Special Sense Organs
• Taste and smell sense organs respond to chemical
stimuli.
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Taylor: Memmler’s Structure and function of the Human Body
Other Special Sense Organs
Sense of taste (gestation)
• Receptors (taste buds)
– Sweet
– Salty
– Sour
– Bitter
– Umami
• Nerve supply
– Facial nerve
– Glossopharyngeal nerve
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Taylor: Memmler’s Structure and function of the Human Body
Other Special Sense Organs
Sense of smell (olfaction)
– Receptors in upper nasal cavity
– Nerve supply via olfactory nerve
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Taylor: Memmler’s Structure and function of the Human Body
Sense of Smell
• Smell receptors in nasal cavity
– Stimulated by substances in solution in nasal fluids
– Smells stimulate appetite and flow of digestive juices
• Olfactory nerve (cranial nerve I)
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-16 Special senses that respond to chemicals.
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Taylor: Memmler’s Structure and function of the Human Body
Other Special Senses
Checkpoint
10-16
What are the special senses that respond to
chemical stimuli?
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Taylor: Memmler’s Structure and function of the Human Body
The General Senses
Learning Outcomes
14. Explain the function of
proprioceptors.
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Taylor: Memmler’s Structure and function of the Human Body
The General Senses
• Receptors scattered throughout the body sense
• Touch
• Pressure
• Heat
• Cold
• Position
• Pain
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Taylor: Memmler’s Structure and function of the Human Body
The General Senses
Sense of Pain
• Pain receptors
– Are free nerve endings
– Are found in skin, muscles, joints and (to a lesser
extent) in most internal organs
• Pain relief
– Analgesic drugs
– Anesthetics
– Endorphins
– Heat or cold
– Relaxation or distraction techniques
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Taylor: Memmler’s Structure and function of the Human Body
Sensory Adaptation
• Occurs when receptors are exposed to continuous
stimulus
• Some receptors can adjust themselves so sensation
becomes less acute.
• Receptors adapt at different rates.
• Pain receptors do not adapt.
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Taylor: Memmler’s Structure and function of the Human Body
Figure 10-17
Sensory receptors
in the skin.
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Taylor: Memmler’s Structure and function of the Human Body
The General Senses
Checkpoints
10-17
What are examples of general senses?
10-18
What are proprioceptors and where are they
located?
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Taylor: Memmler’s Structure and function of the Human Body
The General Senses
Pop Quiz
10.5
If you hold your arm motionless in the air, which
receptors are most important in informing you of
your hand position?
A) Proprioceptors
B) Pressure receptors
C) Tactile corpuscles
D) Free nerve endings
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Taylor: Memmler’s Structure and function of the Human Body
The General Senses
Pop Quiz Answer
10.5
If you hold your arm motionless in the air, which
receptors are most important in informing you of
your hand position?
A) Proprioceptors
B) Pressure receptors
C) Tactile corpuscles
D) Free nerve endings
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Taylor: Memmler’s Structure and function of the Human Body
Case Study
Learning Outcome
15. Using the case, discuss
changes in the anatomy and
physiology of the eye
resulting from chronic sun
exposure.
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Taylor: Memmler’s Structure and function of the Human Body
Word Anatomy
Learning Outcome
17.
Show how word parts are
used to build words related to
the sensory system.
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Taylor: Memmler’s Structure and function of the Human Body
Word Anatomy
Word Part
Meaning
Example
ophthalm/o
eye
An ophthalmologist is a physician who
specializes in treatment of the eye.
presby-
old
Presbyopia is farsightedness that
occurs with age.
tympan/o
drum
The tympanic membrane is the
eardrum.
ot/o
ear
Otology is the study of the ear.
propri/o
own
Proprioception is perception of one’s
own body position.
kine
movement
Kinesthesia is a sense of body
movement.
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Taylor: Memmler’s Structure and function of the Human Body
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins