Chapter 6
Section 4: Other Senses
Taste: Savory Sensations
• Taste occurs because chemicals
stimulate thousands of receptors in
the mouth, primarily on the tongue,
but also in the throat, cheeks, &
roof of mouth
• Papillae: Knoblike elevations on the
tongue, containing the taste buds
• Actual receptors for taste are inside the
taste buds
–Cells send tiny fibers out through an
opening in the bud
–Receptor cells are replaced by new
cells every ten days
–After 40, total number of taste buds
declines
• Bitterness & sourness help us
identify foods that are rancid or
poisonous
• Sweetness helps us identify foods
that are healthful or rich in calories
• Salt is necessary for all bodily
functions
• Basic tastes can be perceived at any
spot on the tongue
–Center has no taste buds
• Taste differences are genetic, a
matter of culture & learning
• Attractiveness of a food can also be
affected by its color, temperature,
texture, & odor
Smell: The Sense of Scents
• Smell or olfaction
• Airborne chemical molecules enter the
nose & circulate through the nasal
cavity.
–Vapors can also enter through the
mouth & pass into nasal cavity.
• Sniff out dangers by smelling
smoke, food spoilage, &
poisonous gases
–Loss can be caused by
infection, disease, injury, or
smoking
• Red bars show the
people who could
identify a substance
dropped on the
tongue when they
were able to smell it
• Blue bars show the
people who could
identify the substance
when they were not
able to smell it
Senses of the Skin
• Protects our innards, helps identify
objects, establish intimacy with others,
gives us a sense of ourselves as a distinct
from the environment
• Basic senses- touch/pressure, warmth,
cold, & pain
–Tickle, itch, & burning
The Mystery of Pain
• When the stimulus producing it is
removed, the sensation may
continue, sometimes for years
• Chronic pain disrupts lives, puts
stress on the body, & causes
depression, & despair
The Gate Control Theory of Pain
• Experience of pain
depends (in part)
on whether the
pain impulse gets
past neurological
“gate” in the spinal
cord & thus reaches
the brain.
• Brain influences the gate
–Thoughts & feelings can
influence our reactions to pain
Updating the Gate Control Theory
• Doesn’t explain phantom pain
• Brain not only responds to incoming
signals from sensory nerves but is also
capable of generating pain entirely on its
own
–A network of neurons in the brain
gives us a sense of our own bodies &
body parts
Neuromatrix Theory of Pain
• Theory that the
matrix of neurons
in the brain is
capable of
generating pain (&
other sensations) in
the absence of
signals from
sensory nerves
The Environment Within
• Kinesthesis: The sense of body
position and movement of body
parts
–Information provided by pain &
pressure receptors located in
muscles, joints, & tendons
• Equilibrium: The sense of balance
–Gives us information about our bodies as a
whole
–Relies on three semicircular canals in the
inner ear
• Tubes are filled with fluid that moves &
presses on hair like receptors whenever
the head rotates
• Receptors intake messages that
travel through a part of the
auditory nerve not involved in
hearing