Other Senses - Cloudfront.net

Other Senses
Psychology: Chapter 4, Section 4
Other Senses
• Vision and hearing are just two of our senses
• Other senses are smell, taste, and the skin and
body senses
• With vision and hearing, physical energy in the
form of light or sound waves stimulates our
sensory receptors
• Smell and taste are called chemical senses, as we
sense molecules of substances
• The skin detects touch through pressure,
temperature, and pain
• Body senses alert us to posture and movement
• The olfactory system is the sensory system used for
olfaction, or the sense of smell
• People do not have as strong a sense of smell as
many animals
• Dogs use seven times as much of the cerebral
cortex for smell as people do
• But smell is important for people too
• Without smell, we could not taste things as well,
and onions and apples would taste the same as
each other
Smell- Taste Relationship
• The smell of food
not only goes
through our
nostrils (nasal
odor) but also up
the back of the
(retronasal odor)
to the nose.
• These smells help
us sense flavor
• Odors happen when molecules (in the form of a
gas) spread from the object causing the odor
• Receptor neurons high in the nostrils react to the
gas, and send information to the olfactory nerve,
which sends the message to the brain
• We adapt rapidly to odors
• This may be good in a smelly locker room, but not
so good if there is a dangerous gas leak in the house
Inside your nose
is the olfactory
which is a fancy
word for “smell
In the olfactory
epithelium are
more than 10
million scent
These receptors
can distinguish
up to 10,000
different smells.
• Never feed a dog chocolate (it could give him or her
a heart attack), but dogs do love candy. Cats, on the
other hand, don’t particularly like candy. Dogs can
taste sweetness, while cats cannot
• People have at least four basic taste senses– sweet,
sour, salty, and bitter. (Some say another sense is
umami, Japanese for “meaty” or “savory.”)
• Our tongue has taste buds, which are receptor
• People have different concentrations of taste buds,
leading to some people really enjoying spicy food,
while others do not tolerate it
• It is possible to damage taste buds from hot foods
or scraping your tongue, but fortunately, taste
receptor cells reproduce rapidly, unlike other
sensory neurons (like hearing or vision)
Taste buds are
organized and
together on
the tongue in
distinct areas
Skin Senses
• The sense of touch could more accurately be
further categorized into senses of pressure,
temperature, itch and pain, so they are
collectively called the skin senses
The sense of “touch” is actually many
different kinds of senses
• Certain areas of our body are more sensitive to
the sense of pressure than other areas
• For example, your fingertips, lips, and cheeks are
more sensitive than your shoulders or calves
• We have hair cells that help with our sensitivity to
pressure, as sensory receptors near the hair roots
fire when skin is touched
• There are also other structures under the skin to
help with sensitivity to pressure
• Touch is very important for a newborn baby to
One way to measure touch sensitivity is to
see how far apart two points need to be to
be felt as two points
It’s very important for a baby to be held
(they should not be just left alone in a baby
seat all the time)
• Sensations of temperature on our skin are relative.
If we are feverish, things that might normally feel
warm could actually feel cold.
• We have receptors just below our skin surface that
sense either hot or cold temperatures, and thus fire
• We adapt to hot or cold rather quickly. A cold pool
or a hot bath seems relatively comfortable after just
a few minutes.
When we have
a high fever, we
can ironically
feel very cold
• How can pain be helpful?
• Pain can protect us from further harm, by either
having us pull away from a source of injury or
immobilizing an injured area
• As with pressure receptors, pain receptors are not
evenly divided around the body– the sole of your
foot is not as sensitive to pain as your neck
A swelling can help immobilize a joint that
shouldn’t move, and may work as a splint
• The pain message travels quickly from the source of
the pain to the spinal cord, to the thalamus, to the
cerebral cortex, where the location and severity of
the pain is interpreted
• Chemicals called prostaglandins send pain messages
to the brain
• Aspirin and ibuprofen curb production of
prostaglandins, thus reducing how much pain we
While all four of these do relieve pain and
fever, Tylenol does not reduce swelling
• Why does rubbing an injured area sometimes help
relieve pain?
• One possible answer is the gate theory of pain
• Gate theory suggests that only a certain amount of
information can be processed by the nervous
system at a time
• Rubbing an area may flood the brain with other
sensations, reducing the amount of pain messages
able to make it through
Large nerve
fibers are fast
stimulated by
rubbing. They
close the gate
on pain
• Many people who have lost a limb experience pain
in the limb that is no longer there
• This is known as “phantom limb pain”
• There are nerves in the remaining stump of the
missing limb that have memories connected with
the limb
These are the characteristic sensations
of phantom limb pain after a leg has
been amputated below the knee
Body Senses
• Body senses help you stay upright and put food in
your mouth without looking
• There are two main body senses: the vestibular
sense and the kinesthetic sense
• Your vestibular sense lets you know whether you
are upright or falling, or changing speeds in a
• Your kinesthetic sense also lets you know the
position and motion of your body, and allows you to
touch your nose with your eyes closed or feed
yourself with a fork
The semicircular canals in your ear help you
keep your balance via your vestibular sense
Alcohol affects your kinesthetic sense,
and so a common roadside test is for
suspects to close their eyes, tip back
their head, and touch their nose
• Answer all three questions on page 92 and
turn that in