Building on the discussion of the nervous system in Chapter

13, we now explore how sensory receptors and nerves

detect and convey information to the brain.

You will draw on what you have learned about action poten-

tials, neurotransmitters, synapses between neurons and

other cells, and nerves (13.2–13.6).

You will also learn more about how the brain processes sen-

sory input of all kinds (13.8).

Key ConCepts

LinKs to earLier ConCepts

265

Sensory Receptors and

Pathways

Different kinds of sensory receptors

detect different types of stimuli.

When signals from sensory sys-

tems are decoded in the brain, we

become aware of sights, sounds,

odors, pain, and other sensations.

Section 14.1

Scratching an itch is a powerful drive.

And as it turns out, what seems like a simple response is anything

but. When scientists used MRI scanning to observe the brains

of “itch-test” volunteers, they discovered that scratching an itch

stimulates sensory areas as well as brain centers involved in

pleasure, addiction, and motivation. In this chapter we look at the

functioning of the structures that make up our sensory systems.

Together these systems are a major means by which the brain

obtains information that it may use to help manage the body’s

biological affairs.

Top: © Viorel Sima/Shutterstock.com; Middle: both © Cengage

Learning; Bottom: Dr. P. Marazzi/Science Source

sensory systems

14

Somatic Senses

Receptors found at more than

one location in the body produce

somatic (body) sensations such as

touch, pressure, temperature, and

pain. Section 14.2

Special Senses

Receptors for the special senses

detect chemicals (taste and smell),

light (vision), sound waves (hearing),

and changes in the body’s posi-

tion (balance). Sections 14.3–14.6,

14.8 –14.9

Disorders of the Ears and

Eyes Sections 14.7, 14.10

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