Thibodeau: Anatomy and Physiology, 5/e
Chapter 15: Sense Organs
Students will probably not be aware that there are literally millions of sense organs in the body
and that these are differentiated as either general sense organs or special sense organs. Of these, by far the
most numerous are the general sense organs, or receptors. In addition to classification by location and
structure, the textbook classifies these receptors according to the types of stimuli that activate them.
Chapter 15 identifies stimuli detected by the somatic senses and the function of the major components of
each of the special sense organs as well. It is important to point out that both the somatic senses and the
special senses initiate reflexes important for homeostasis.
Objectives
After students have completed this chapter, they should be able to:
1.
Compare the function of general and special sense organs.
2.
Classify receptors according to the types of stimuli that activate them.
3.
Identify the stimuli detected by the somatic senses.
4.
Describe the receptors for pain, temperature, touch, pressure, and stretch.
5.
Discuss the structure and the function of the olfactory and taste sense organs.
6.
Describe the dual sensory functions of the ear.
7.
List and discuss the function of the major anatomical components in the external, middle, and
inner ear.
8.
Identify the hearing sense organ and describe its function.
9.
Discuss the physiology of hearing.
10.
Identify and describe the sense organs involved in the sense of balance.
11.
Identify the major anatomical structures that are visible in a horizontal section through the eyeball.
12.
Describe the layers that make up the retina.
13.
Compare the structure, function, and location of rods and cones in the retina.
14.
Discuss the cavities and humors of the eye.
15.
List and give the function of the extrinsic and intrinsic eye muscles.
16.
Identify the accessory structures of the eye.
17.
Discuss the four processes that focus light rays on the retina and describe the most common errors
of refraction.
18.
Describe the function of photopigments.
Lecture Outline
I.
II.
Introduction (p. 448)
A.
General sensory receptors
B.
Specialized sensory receptors
Sensory Receptors (p. 448)
A.
Receptor response
B.
Distribution of receptors
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Chapter 15: Sense Organs
III.
2
Classification of Receptors (p. 449)
A.
B.
C.
Classification by location (Fig 15-1; Table 15-1)
1.
Exteroceptors (Fig. 15-1)
2.
Visceroceptors (interoceptors)
3.
Proprioceptors (Fig. 15-1)
a.
Tonic receptors
b.
Phasic receptors
Classification by stimulus detected (Table 15-1)
1.
Mechanoreceptors
2.
Chemoreceptors
3.
Thermoreceptors
4.
Nociceptors
5.
Photoreceptors
Classification by structure (Table 15-1)
1.
2.
Free nerve endings
a.
Nociceptors
b.
Root hair plexuses
c.
Merkel discs
Encapsulated nerve endings
a.
b.
IV.
Touch and pressure receptors
1)
Meissner's corpuscle
2)
Krause's corpuscle
3)
Ruffini's corpuscle
4)
Pacinian corpuscle
Stretch receptors
1)
Muscle spindles
2)
Golgi tendon receptors
Special Senses (p. 453)
A.
B.
C.
Sense of smell (p. 453)
1.
Olfactory receptors (Fig. 15-2)
2.
Olfactory pathway (Figs. 15-2, 15-3)
Sense of taste (p. 455)
1.
Taste buds (Fig. 15-4)
2.
Neuronal pathway for taste (Fig. 15-3)
Sense of hearing and balance: the ear (p. 456)
1.
External ear (Fig. 15-5)
2.
Middle ear (Fig. 15-5)
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Chapter 15: Sense Organs
3.
3
Inner ear (Figs. 15-5, 15-6)
a.
b.
c.
Bony labyrinth (filled with perilymph)
1)
Vestibule
2)
Cochlea
3)
Semicircular canals
Membranous labyrinth (filled with endolymph)
1)
Utricle and saccule in vestibule
2)
Cochlear duct inside cochlea
3)
Membranous semicircular canals
Cochlea and cochlear duct (Fig. 15-6)
1)
Scala vestibuli (communicates with oval window)
2)
Scala tympani (communicates with round window)
3)
Cochlear duct (membranous labyrinth) (Fig. 15-6)
(Fig. 15-6)
(Fig. 15-6)
a)
Vestibular membrane (roof)
b)
Basilar membrane (floor)
(1)
Organ of Corti (rests on basilar
membrane)
(a)
Movement sensed by hair
(b)
Sensory neuron dendrites
(attach to organ of Corti)
cells
d.
e.
Sense of hearing (p. 459)
1)
Detection of loudness and pitch (Fig. 15-7)
2)
Pathway of sound waves (Fig. 15-7)
3)
Neuronal pathway of hearing
Sense of balance
1)
Static equilibrium: utricle and saccule in vestibule
2)
Dynamic equilibrium: semicircular canals (Fig. 15-9)
(Fig. 15-8)
D.
Vision: the eye (p. 464)
1.
Structure of the eye (Figs. 15-10, 15-11, 15-12, 15-13)
a.
Coats of the eyeball (Table 15-2)
1)
Fibrous tunic—outer coat (sclera and cornea)
2)
Vascular tunic—middle coat (choroid, ciliary body,
3)
Nervous tunic—inner coat (retina)
and iris)
b.
Cavities and humors (Table 15-3; Figs. 15-10, 15-11)
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Chapter 15: Sense Organs
4
1)
Posterior cavity (contains vitreous humor)
2)
Anterior cavity (contains aqueous humor) (Fig. 15-
14)
c.
d.
Anterior chamber (anterior to iris)
b)
Posterior chamber (posterior to iris)
Muscles (p. 467)
1)
Extrinsic eye muscles (Fig. 15-15)
2)
Intrinsic eye muscles (Figs. 15-10, 15-11)
Accessory structures (Figs. 15-16, 15-17, 15-18)
1)
Eyebrows and eyelashes
2)
Eyelids (Fig. 15-16)
3)
2.
a)
a)
Superior and inferior palpebrae
b)
Palpebral fissure
c)
Medial canthus and caruncle
d)
Lateral canthus
e)
Conjunctiva
Lacrimal apparatus (Fig. 15-18)
a)
Lacrimal glands
b)
Lacrimal ducts
c)
Puncta
d)
Lacrimal canals
e)
Lacrimal sac
f)
Nasolacrimal duct
The process of seeing (p. 469)
a.
b.
Formation of retinal image
1)
Refraction of light rays
2)
Accommodation of lens (Fig. 15-19)
3)
Constriction of pupil
4)
Convergence of eyes
The role of photopigments (p. 470)
1)
Rods (Fig. 15-20)
2)
Cones
a)
c.
Three types of photopigments:
(1)
Erythrolabe
(2)
Chlorolabe
(3)
Cyanolabe
Neuronal pathway of vision (Fig. 15-21)
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Chapter 15: Sense Organs
V.
VI.
VII.
5
Cycle of Life: Sense Organs (p. 473)
A.
Structure and function response capabilities limited in newborns
B.
With maturation, normal development of responses progresses
C.
Loss of sensory capability with old age
The Big Picture: Sense Organs (p. 473)
A.
Wide distribution throughout the body
B.
Provide information related to conditions that affect homeostasis
C.
Detect changes that might be harmful or cause injury
Mechanisms of Disease (p. 473)
A.
Ear disorders
1.
Conduction impairment
a.
2.
B.
Blockage of external auditory canal
1)
Wax
2)
Tumors
b.
Otosclerosis
c.
Otitis
Nerve impairment
a.
Presbycusis
b.
Mèniér disease
Eye disorders
1.
2.
3.
Refraction disorders
a.
Myopia
b.
Hyperopia
c.
Presbyopia
d.
Astigmatism
e.
Cataracts
f.
Infections
Disorders of the retina
a.
Retinal detachment
b.
Diabetic retinopathy
c.
Glaucoma
d.
Nyctalopia
Visual pathway disorders
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