Somatic Senses Are Related to Detection of
Pressure, Chemicals, Proprioception, and Touch
LEARNING OBJECTIVES
1.
Describe
the location and function
of receptors for the somatic senses
(tactile, thermal, pain).
2.
Identify
the receptors for propriocep-
tion and describe their functions.
3.
Describe
the neural pathways in-
volved in somatic senses.
ou know about the world around
you through
sensations
and
per-
ceptions
. Sensations are detect-
ed by specialized nerve receptors
that detect a change in the body’s internal or external
environment. Each receptor is specific to a par-
ticular type of sensation. When a receptor is
stimulated, it initiates a signal in the associat-
ed dendrite, which conducts impulses related
to the sensation to the central nervous system
(CNS).
Somatic
sensations
include
tactile,
pain, temperature, and proprioception. Recep-
tors for the somatic senses are spread diffusely
around the body in structures such as the skin,
mucous membranes, muscles, tendons, and
joints (Figure 8.1a).
Visceral senses have receptors within the
walls of the internal organs that detect pain and
sensation
Con-
scious or subcon-
scious awareness of
changes in internal or
external environment;
can occur in all parts
of the CNS.
perception
Con-
scious awareness and
interpretation of sen-
sations; occurs only in
the cerebral cortex.
a.
Somatic senses
Tactile sensations: touch, pressure,
vibration
Nociception (pain)
Proprioception: joint and muscle position,
movements of head and limbs
Thermal sensations: hot, cold
b. Visceral senses
(conditions within the
organs)
• Pain
• Changes in
levels of
chemicals
• Blood pressure
O verview o f se n satio n s • Figure 8.1
The neural pathway for sensations consists of the following: Stimulus ^ sensory receptor
^ neural pathway ^ brain (integrate nerve impulses) ^ sensation. For example, when
the skin of the cheek is touched, sensory receptors are stimulated, and a nerve impulse is
transmitted through the trigeminal nerve (cranial nerve V) to the cerebrum for integration
leading to perception of the sensation.
Receptors in
skin, muscles,
and joints
Receptors in
nose, eyes, ears
and mouth
Receptors
I
in organs
228 CHAPTER 8
Somatic Senses and Special Senses
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