CHEMICAL SENSES ACTIVITY
Background
The nervous systems functions to combined various sensations of an animal’s
world into a meaningful whole such that the organism can meaningfully respond
to the world. Thus, the nervous system relies on various senses that allow an
animal to sense particular characteristics regarding an organisms internal and/or
external environment. An animal’s senses are specialized for particular types of
environmental characteristics and the senses are categorized as being somatic
senses that are distributed throughout the body and special senses that are often
located in the head region of the animal. In the following activities, you will
become familiar with the basic function of the special senses that involve
chemicals.
Materials
small cups
taste solutions
cotton swabs
circle paper reinforcers
life savers candies
Procedure
Special Senses
Taste (Mapping the Tongues Senses)
1. Acquire samples of each of the labeled solutions by filling a portion in one of
the small cups provided.
2. Dry your tongue off and place a paper reinforcement circle on the tip of your
tongue.
3. Place the tip of a fresh cotton swab into the solution labeled A, and then use
the tip of the swab to swab the area inside the paper reinforcement circle. If
you sense a taste record this in your data table with a “+”. Otherwise, record
a “-“.
4. Place the other end of the cotton swab into tap water and place this in the
swab area to clear out the previous taste. Then, proceed to test and record
data on the three remaining solutions, making sure to use tap water between
tests.
5. Acquire more reinforcement circles and place them in the middle and both
sides (middle and back) of your tongue and test and record the data for these
area as well.
6. Finally, match the solutions with their type of taste (sweet, sour, bitter, or
salty), and answer the questions on taste sensation.
Smell (The effect of smell on taste sensation)
1. Acquire at least five of the flavors of lifesavers.
2. Then, have a test administrator place a randomly chosen lifesaver on your
outstretched tongue while you have your eyes and nose closed.
3. While your eyes and nose are closed, guess the flavor of the lifesaver and
have the test administrator record your guess.
4. Then, open your nose and taste the flavor of the lifesaver. If your perception
of the lifesavers flavor changed record this new flavor as well.
5. Calculate and record the percentage of correct guesses both without smell and
with smell.
6. Finally, answer the appropriate question about smell.
Data Tables
Special Senses
Taste
Solutions
Tip
Tongue Areas
Mid-Sides
Back-Sides
L
R
L
R
A.
B.
C.
D.
Smell
Lifesaver
1
2
3
4
5
Flavor
Without
Smell
Flavor
With
Smell
Actual
Flavor
%
Correct
Middle
Activity Questions
1. Create a diagram of the location of the major sweet, sour, salty, and bitter
taste receptors on your tongue, and hypothesize why the receptors may be
segregated into distinct regions.
2. Describe your data collected in lifesaver test, and explain why the differences
you observed are logical.
Homework Questions
3. What are the scientific terms for the sensations of taste and smell?
4. Diagram the anatomy of a taste bud.
5. Diagram and describe the different manners in which sensory transduction
occurs in different taste receptor cells.
6. List the specific steps that result in the release of neurotransmitters by taste
receptor cells.
7. Describe the steps in odorant binding and the depolarization of cells that
sense smells.