BACKGROUND:
The tongue lies along the mouth but it begins in the
throat. The tongue has several functions including acting as
an organ of taste, aids in chewing, helps you swallow, helps keep
your teeth clean, and is essential to speech.
Four areas of the tongue have been identified with four different
tastes. The area at the back of the tongue is the area of bitter
taste. The area in the middle of the tongue on both sides is the
area of sour taste. The front of the tongue is the area of salty
taste. The very tip of the tongue is the area of sweet taste.
Exactly how we taste is not fully understood. We can only
taste those substances which can dissolve or are soluble in water.
The sensation of taste results from the stimulation of certain nerve endings.
The nerve endings are located within the taste buds. Much of the
sensation that we know as taste is really the sensation of smell.
When apples or onions are chewed, the vapors enter the inner openings of
the nose. There, they reach the nerve endings for smell, and one
can distinguish between them.
Food must be moist in order for the tongue to be able to
taste them. Substances must be dissolved in order for them to be
tasted. This is why the sugar cube could not be tasted.
Some students may have trouble distinguishing bitter from sour.
This is an abstract thought that many people cannot understand.
The tongue is part of the digestive system and the nervous system.
In the post lab, students will investigate what happens to the food after
it is eaten.
PROCEDURE:
- Dry your tongue with a towel. Put a sugar cube
on your tongue.
- Dip a cotton swab into a solution of each item and find out
which area of your tongue has the sweetest, sourest, and saltiest sensation.
Sip water after each item. Do this experiment carefully. Make
sure that you have students keep a sanitary area. Do not reuse cotton
swabs
