liquid they secrete is the saliva which flows into your mouththroughtubes
located at each sideofyourupperjaw.
The roofofyourmouth(called the upperpalate)ishardwhen you run
yourtongue over it and seems to have a slightly ridgedbonystructureunder
the moist covering tissue.
Yourtongue ismuscularand has aroughsurface due to the presenceof
many extremely tiny"bumps."Each different kind of toothhas acertainshape and size sothatit can
performa certain function.
Thechisel-shapedincisors areadaptedfor biting andcuttingfood.
The canines are especially fitted for holding and tearingcertainkinds of
food such as meat. Beavers have sharp, ever-growing canines for gnawing
wood. Dogs, wolves and similar animals are called "canines," because of
their long,sharpteeth fortearingmeat.
The large bumpy molars with their hill-like surfaces are adapted for
grindingandcrushingfood.
When you are between 18 and 24 years old, you may develop twoadditional
pairs ofmolars, one in the upperand one in the lowerbackofeach jaw.
These are"wisdom"teeth, and if yours develop, you will have atotalof 32
teeth. Thereis so littleroomin thehumanjaw for these largeteeththatoften
they do notgrowoutof the jaw, butbecome lodged in thejawbone. They
are then said to beimpacted.
Yourtongue is an aid to chewing, because it moves the foodaroundthe
mouthas it isbrokendown by the different kindsofteeth. Italso helps the
food become mixed with the saliva, secreted by glands inbothcheeks, so as
to make swallowing easier. Theroughsurfaceofthetongueis caused by the
presence ofmanytiny"tastebuds." Withoutthese you wouldnotbe able to
distinguishamongsweet, sour, bitterand saltytastingfoods.
IDENTIFYING FOODS BY TASTE ALONE
Materials:Small peeled cubes of raw apple, carrot,onion,potato,celery
and turnip,a pair oftweezers. Ask oneofyourparentsor a friend towork
with you on thisexperiment.
Follow this procedure: If you are thetaster,haveyourassistantblindfold
you. Holdyour nose(thatis, pinch it closed with a thumband forefinger)
whiletasting. Yourassistantshouldplaceeachsample food onyourtongue,
one at a time, and youshouldidentify each one by taste alone. Haveyour
friend make arecordofyourresponses.