Download Behavioral Objectives

CHAPTER 14
SENSES
BEHAVIORAL OBJECTIVES
1. Identify the various receptors and explain how they are classified according to the type of stimuli they receive.
[14.1, p.272, Table 14.1]
2. Explain how a sensation occurs. [14.1, p. 273, Fig. 14.2]
3. Describe the function of proprioceptors. [14.2, p.274, Fig. 14.3]
4. Discuss the general receptors of the skin. [14.2, p.275, Fig. 14.4]
5. Describe the senses that rely on chemoreceptors. [14.3, p.276, Fig. 14.5-14.6]
6. Explain how chemoreceptors operate. [14.3, pp.276-277, Fig. 14.5-14.6]
7. Describe the anatomy of the eye and the function of each part. [14.4, pp.278-280, Fig. 14.7, Table 14.2]
8. Describe the receptors for sight, their mechanism of action, and the mechanism for stereoscopic vision. [14.4,
pp.280-282, Fig. 14.8-14.11]
9. Identify common abnormalities of the eye. [14.4, p.283, Fig. 14.12]
10. Describe the anatomy of the ear and the function of each part. [14.5, pp.284-285, Fig. 14.13]
11. Discuss the receptors for hearing and their mechanism of action. [14.5, pp.284-285, Fig. 14.14]
12. Discuss the receptors for rotational and gravitational equilibrium and their mechanisms of action. [14.6, pp.286287, Fig. 14.15, Table 14.3]
13. List ways to prevent loss of vision and hearing. [pp. 288-289, Health Focus, Fig. 14A, Table 14A]
14. Understand and use the bold-faced and italicized terms included in this chapter. [Understanding Key Terms,
p.291]
EXTENDED LECTURE OUTLINE
14.1 Sensory Receptors and Sensations
Each type of sensory receptor responds to a particular kind of stimulus. Exteroceptors detect stimuli from outside the
body while interoceptors detect internal stimuli.
Types of Sensory Receptors
There are chemoreceptors (respond to chemical substances), pain receptors (a type of chemoreceptor that responds
to chemicals released by damaged tissues), photoreceptors (respond to light), mechanoreceptors (respond to
mechanical forces), and thermoreceptors (respond to temperature changes).
How Sensation Occurs
When stimulation occurs, sensory receptors initiate nerve impulses that are transmitted to the spinal cord and/or
brain. Sensation occurs when nerve impulses reach the cerebral cortex. Perception is an interpretation of the
meaning of sensations.
Mader VRL CD-ROM
Image 0269l.jpg (Fig. 14.1)
Image 0270l.jpg (Fig. 14.2)
Mader ESP Modules Online
Animals/Sense Organs/Introduction
Transparencies
205 (Fig. 14.2)
14.2 Proprioceptors and Cutaneous Receptors
Proprioceptors
Proprioception is illustrated by the action of muscle spindles which are stimulated when muscle fibers stretch. A
reflex action, which is illustrated by the knee reflex, causes the muscle fibers to contract. Proprioception helps
maintain balance and posture.
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Cutaneous Receptors
The skin contains sensory receptors for touch, pressure, pain, and temperature (warmth and cold). Three types of
receptors detect touch: Meissner corpuscles, Merkel disks, and free nerve endings. Pacinian corpuscles, Ruffini
endings, and Krause end bulbs detect pressure. Temperature receptors are free nerve endings.
Pain Receptors
Internal organs as well as the skin have pain receptors (nociceptors). Sometimes stimulation of internal pain
receptors is felt as pain from the skin, a phenomenon known as referred pain.
Mader VRL CD-ROM
Image 0271l.jpg (Fig. 14.3)
Image 0272al.jpg (Fig. 14.4)
Image 0272bl.jpg (Fig. 14.4)
Dynamic Human 2.0 CD-ROM
Nervous/Histology/Pacinian Corpuscle
Mader ESP Modules Online
Animals/Sense Organs/Mechanoreceptors
Transparencies
206 (Fig. 14.3)
207 (Fig. 14.4)
14.3 Chemical Senses
Chemoreceptors in the carotid arteries and aorta are sensitive to the pH of the blood. Taste and smell are chemical
senses that are sensitive to molecules in food and air.
Sense of Taste
The taste buds contain taste cells that communicate with sensory nerve fibers. The brain determines the taste
according to overall pattern of incoming impulses from taste buds sensitive to sweet, sour, salty, or bitter tastes.
Sense of Smell
After molecules bind to receptor proteins on the cilia of olfactory cells, nerve impulses eventually reach the cerebral
cortex, which determines the odor according to the type of olfactory cell stimulated.
Mader VRL CD-ROM
Image 0273l.jpg (Fig. 14.5)
Image 0274al.jpg (Fig. 14.6)
Image 0274bl.jpg (Fig. 14.6)
Dynamic Human 2.0 CD-ROM
Nervous/Explorations/Taste
Nervous/Explorations/Zones of Taste
Nervous/Explorations/Innervation of the Tongue
Nervous/Explorations/Olfaction
Life Science Animations VRL 2.0
Animal Biology/Sensory Systems/Taste
Animal Biology/Sensory Systems/ Taste Buds in Humans
Animal Biology/Sensory Systems/Smell
Animal Biology/Sensory Systems/ Olfactory Cells in Humans
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Animals/Sense Organs/Chemoreceptors
Transparencies
208 (Fig. 14.5)
209 (Fig. 14.6)
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14.4 Sense of Vision
Vision is dependent on the eye, the optic nerves, and the visual areas of the cerebral cortex.
Anatomy of the Eye
The eye has three layers. The outer layer, the sclera, can be seen as the white of the eye; it also becomes the
transparent bulge in the front of the eye called the cornea. The middle, pigmented layer, called the choroid, absorbs
stray light rays. The rod cells and the cone cells are located in the retina, the inner layer of the eyeball. Aqueous
humor fills the anterior compartment of the eye; vitreous humor fills the posterior compartment.
Focusing
The cornea, the humors, and especially the lens bring the light rays to focus on the retina. To see a close object,
visual accommodation occurs as the lens rounds up
Photoreceptors
The rods permit vision in dim light at night, and the cones permit vision in bright light needed for color vision.
Breakdown of rhodopsin in rods initiates nerve impulses. There are three types of cones (blue, green, or red) that
also contain pigments composed of retinal and opsin.
Integration of Visual Signals in the Retina
The retina has three layers of neurons. The rod and cones synapse with the bipolar cells, which in turn synapse with
ganglion cells that initiate nerve impulses. As signals pass from layer to the next integration occurs because each
layer contains fewer cells than the previous layer.
Blind Spot
There are no rods and cones where the optic nerve exits the retina. This is the blind spot.
Integration of Visual Signals in the Brain
The visual pathway and the visual cortex take the visual field apart, but the visual association areas rebuild it so we
correctly perceive the visual field.
Abnormalities of the Eye
Color Blindness
The most common abnormality is a lack of red and/or green cones.
Distance Vision
There are nearsighted (corrected by concave lens) with a elongated eyeball and farsighted (corrected by
convex lens) individuals with a shortened eyeball. Astigmatism is corrected by an unevenly ground lens.
Mader VRL CD-ROM
Image 0275l.jpg (Fig. 14.7)
Image 0276l.jpg (Fig. 14.8)
Image 0277al.jpg (Fig. 14.9)
Image 0277bl.jpg (Fig. 14.9)
Image 0278al.jpg (Fig. 14.10)
Image 0278bl.jpg (Fig. 14.10)
Image 0279l.jpg (Fig. 14.11)
Image 0280l.jpg (Fig. 14.12)
Dynamic Human 2.0 CD-ROM
Nervous/Explorations/Vision
Nervous/Histology/Eye
Nervous/Histology/Retina
Nervous/Clinical Concepts/Nearsighted vs. Farsighted
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Animal Biology/Sensory Systems/Vision
Animal Biology/Sensory Systems/ Visual Pathway
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Animals/Sense Organs/Light Receptors
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Transparencies
210 (Fig. 14.7)
211 (Fig. 14.8)
212 (Fig. 14.9)
213 (Fig. 14.10)
214 (Fig. 14.11)
215 (Fig. 14.12)
14.5 Sense of Hearing
Hearing is a specialized sense dependent on the ear and its mechanoreceptors, called hair cells.
Anatomy of the Ear
The ear is divided into three parts: outer, middle, and inner. The outer ear consists of the pinna and the auditory
canal, which direct sound waves to the middle ear. The middle ear begins with the tympanic membrane and contains
the ossicles (malleus, incus, stapes). The malleus is attached to the tympanic membrane, and the stapes is attached to
the oval window, which is covered by membrane. The fluid-filled inner ear contains the cochlea and the semicircular
canals.
Process of Hearing
Hearing begins when the outer and middle portions of the ear convey and amplify the sound waves that strike the
oval window. Its vibrations set up pressure waves within the cochlea, which contains the spiral organ, consisting of
hair cells whose stereocilia are embedded within the tectorial membrane. When the stereocilia of the hair cells bend,
nerve impulses begin in the cochlear nerve and are carried to the brain.
Mader VRL CD-ROM
Image 0281al.jpg (Fig. 14.13)
Image 0281bl.jpg (Fig. 14.13)
Image 0282al.jpg (Fig. 14.14)
Image 0282bl.jpg (Fig. 14.14)
Dynamic Human 2.0 CD-ROM
Nervous/Explorations/Hearing
Life Science Animations VRL 2.0
Nervous/Histology/Organ of Corti
Animal Biology/Sensory Systems/ Anatomy of Human Ear
Animal Biology/Sensory Systems/Hearing
Mader ESP Modules Online
Animals/Sense Organs/Mechanoreceptors
Case Studies Online
Hearing Loss and Jobs
Transparencies
216 (Fig. 14.13)
217 (Fig. 14.14)
14.6 Sense of Equilibrium
Mechanoreceptors detect movement of the head and help achieve equilibrium.
Rotational Equilibrium
Rotational equilibrium is dependent on the stimulation of hair cells embedded in the cupula within the ampullae of
the semicircular canals.
Gravitational Equilibrium
Gravitational equilibrium relies on the stimulation of hair cells on an otolothic membrane within the utricle and the
saccule.
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Mader VRL CD-ROM
Image 0283al.jpg (Fig. 14.15)
Image 0283bl.jpg (Fig. 14.15)
Image 0283cl.jpg (Fig. 14.15)
Image 0284l.jpg (Fig. 14A)
Image 0285l.jpg (Fig. TA14.1)
Dynamic Human 2.0 CD-ROM
Nervous/Explorations/Dynamic Equilibrium
Nervous/Explorations/Static Equilibrium
Life Science Animations VRL 2.0
Animal Biology/Sensory Systems/ Sense of Balance
Animal Biology/Sensory Systems/ Sense of Rotational
Acceleration
Mader ESP Modules Online
Animals/Sense Organs/Mechanoreceptors
Transparencies
218 (Fig. 14.15)
219 (Fig. TA14.1)
SEVENTH EDITION CHANGES
New/Revised Text:
This was chapter 13 in the previous edition.
14.1 Sensory Receptors. Table 14.1 Exteroceptors is new and replaces Table 13.1 Special Sense Organs.
Discussions of sensory receptors have been revised. How Sensation Occurs has been revised to include the
influence of the reticular activating system, and how sensory receptors contribute to homeostasis.
14.2 Proprioceptors and Cutaneous Receptors. New A head title identifies and focuses the discussion of
these topics. The topics Cutaneous Receptors and Pain Receptors were revised.
14.6 Sense of Equilibrium. Terminology has been changed. The term dynamic equilibrium has been
changed to rotational equilibrium, and the term static equilibrium has been changed to gravitational equilibrium.
The Health Focus reading Protecting Vision and Hearing now follows the discussion of hearing and is found at end
of the chapter.
New/Revised Figures:
14.2 Sensation; 14.10 Structure and function of the retina; 14.15 Mechanoreceptors for equilibrium
New/Revised Tables:
14.1 Exteroceptors is new and replaces Table 14.1 Special Sense Organs
STUDENT ACTIVITIES
Blind spot
1. Have students use two marks about 6 inches apart on a piece of paper to demonstrate the blind spot in one eye
(caused by the lack of rods and cones where the optic nerve attaches to the retina). Ask them why they have a
blind spot in each eye and why they never notice it. Point out that the blind spot can lead to serious accidents
while driving and how to avoid this problem.
Taste Tests
2. Use several types of foods to demonstrate how the sense of smell and the texture of food play a role in the sense
of taste. Have students work in small groups. Have one volunteer per group close his or her eyes, open his or
her mouth, and pinch his or her nose. Another student in the group will gently place one of the food items on the
tongue of the volunteer. Instruct the volunteers to determine the type of food they have in their mouths without
chewing or moving it around with their tongues. Next, tell them to chew and try to identify the food. Allow
them to unpinch their noses to see whether that helps determine taste. Have students change roles, with each
person in each group taking a turn at identifying flavors. Items that work well in this test include: small corn
chips; orange segments; thin apple slices; small, flavored gelatin squares; chocolate chips; and gum drops. Be
sure that the student placing the item in the other’s mouth uses sterile tongs or gloves to avoid contamination.
Also, warn students with food allergies that some items might be best avoided.
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Protecting Vision and Hearing
3. Many people do not consider the consequences of vision or hearing loss until loss of these senses begins. Have
your students read the Health Focus “Protecting Vision and Hearing”. Go through the items listed in Table 14A
and have students raise hands for each items they have been exposed to (i.e., shotgun sounds, rock concerts,
loud music from car stereos, etc.) Discuss the consequences of years of exposure to loud noises.
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