15
The Special Senses
The Eye and Vision
(pp. 545–565)
Accessory Structures of the Eye
(pp. 545–549)
Structure of the Eyeball (pp. 549–553)
Optics and the Eye (pp. 553–556)
Photoreceptors and Phototransduction
(pp. 556–563)
Visual Pathways and Processing
(pp. 563–565)
The Chemical Senses:
Smell and Taste
(pp. 565–570)
Olfactory Epithelium and the Sense
of Smell (pp. 565–567)
Taste Buds and the Sense of Taste
(pp. 568–570)
Homeostatic Imbalances of the Chemical
Senses (p. 570)
The Ear: Hearing and Balance
(pp. 570–584)
Structure of the Ear (pp. 570–575)
Physiology of Hearing (pp. 575–579)
Equilibrium and Orientation (pp. 580–584)
Homeostatic Imbalances of Hearing and
Equilibrium (p. 584)
Developmental Aspects of the Special
Senses
(pp. 584–585)
Taste and Smell (pp. 584–585)
Vision (p. 585)
Hearing and Balance (p. 585)
544
P
eople are responsive creatures.
Te aroma of freshly baked bread makes
our mouths water. A sudden clap of thunder makes us jump. Tese stimuli and
many others continually greet us and are interpreted by our nervous systems.
When people are asked to list the senses, they usually come up with five: vision, taste,
smell, hearing, and touch. Actually, touch reflects the combined activity of the general
senses that we considered in Chapter 13. Te remaining senses—
vision, taste
,
smell,
hearing,
and
equilibrium
—are called
special senses
. Most of us tend to forget the sense
of equilibrium, whose receptors are housed in the ear along with the organ of hearing.
In contrast to the widely distributed general receptors (most of which are modified
nerve endings of sensory neurons), the
special sensory receptors
are distinct
receptor
cells
. Tese receptor cells are confined to the head region and are highly localized, either
housed within complex sensory organs (eyes and ears) or in distinct epithelial structures
(taste buds and olfactory epithelium).
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