Goal Four: Explain how the skin,
chemical, kinesthetic, and vestibular
senses work.
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Skin Senses
touch, temperature, and pain
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Chemical
taste and smell
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Kinesthetic
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Vestibular
© 2011 The McGraw-Hill Companies,
Inc.
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The cutaneous senses are the skin receptors on the
skin for temperature, touch, and pain.
With touch, a person is detecting mechanical
energy, or pressure against the skin.
Sensory fibers from receptors in the skin enter the
spinal cord and from there the information travels
to the brain stem. At the brain stem most fibers
from the body cross over to the opposite side of the
brain. The information goes onto the thalamus,
which projects the map of the body’s
somatosensory areas of the parietal lobes in the
cerebral cortex.
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The fingertips contain the most tactile
receptors.
Newborns can experience touch better than
they can see, hear, or even taste.
Females are more sensitive to touch than males.
The human hand sensitivity can not be
matched by even the most sophisticated robots
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Thermoreceptors are located under the skin and
they respond to changes in temperature at or
near the skin. They provide input to keep the
body’s temperature at 98.6 degrees Fahrenheit.
There are both warm and cold
thermoreceptors.
Can we feel temperature?
https://www.youtube.com/watch?v=yXT012
us9ng
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Pain is the sensation that warns of damage to
the body. It works quickly and tells the motor
system of the brain that it must act quickly to
eliminate or minimize the damage.
https://www.youtube.com/watch?v=I3cV2l7
wHBA
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Pain receptors have a higher threshold for
firing than either temperature or touch
receptors. They react mainly to physical stimuli
that distort them or chemical stimuli that
irritate them into action.
In the fast pathway, fibers connect directly to the
thalamus and then to the motor and sensory
areas of the cerebral cortex. This pathway is for
sharp, localized pain such as when a person
cuts themselves.
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In the slow pathway, pain information travels
through the limbic system.
The gate-control theory of pain states that the spinal
column contains a neural gate that can be opened
or closed. When the gate is open it allows the
perception of pain, but when it is closed it does not
allow the perception of pain.
The gate-control theory is no longer seen as true,
but turning pain signals on and off is probably due
to a chemical process involving endorphins.
Culture and ethnic contexts can determine the
degree to which an individual experiences pain.
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Taste and smell are responsible for processing
chemicals in the environment. Taste and smell are
often stimulated at the same time.
Papillae are the small bumps on a person’s tongue that
contain taste buds, which are the receptors for taste.
The information picked up by the taste bud receptors
travels to the brain for interpretation.
The four different taste qualities that a person has are
sweet, sour, bitter, and salty. Different regions of the
tongue are more sensitive to some tastes than other
areas. The tip of the tongue is more sensitive to sweet
and salty, the sides of the tongue are more sensitive to
sour and the rear is more sensitive to bitter.
https://www.youtube.com/watch?v=j7GibFhuBmE
Humans use the sense of smell to decide what to eat
and as an odor tracker.
The olfactory epithelium lines the roof of the nasal
cavity and contains a sheet of receptor cells for smell.
The receptor cells are covered with millions of hairlike antennae.
The neural pathway first goes to the olfactory areas of
the temporal lobes and then goes on to various brain
regions, especially the limbic system.
 https://www.youtube.com/watch?v=9qdor5V0S
Dk
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The kinesthetic senses provide information about
movement, posture, and orientation. The
kinesthetic senses are located in muscle fibers and
joints throughout the body. When a person
stretches or moves, the fibers signal the state of the
muscle.
The vestibular senses provide information about
balance and movement. The vestibular senses tells
a person whether their head is tilted, moving,
slowing down, or speeding up. The proprioceptive
feedback works with the kinesthetic sense to give
information about the position of limbs and body
parts in relation to other body parts.
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The semicircular canals are located in the inner
ear and contain the sensory receptors that
detect head motion.
The brain pathway for the vestibular senses
starts in the auditory nerve and most of the
axons of the vestibular nerve connect with the
medulla, although some go directly to the
cerebellum.
https://www.youtube.com/watch?v=BbKU0
AbbARg
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Goal Five: Discuss the everyday practices
associated with protecting vision and hearing.
Taking care of the eyes means avoiding highfat foods, not smoking, and eating foods rich in
vitamins A, E, C, zinc, and beta carotene. It also
means reading with appropriate lighting and
wearing sunglasses.
To protect hearing, a person should avoid loud
noise. Think about the impact new technology
(iPods and ear buds) is having on our hearing.