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Unit 19: Biology Part 2 Page 110 of 137

 Vanilla extract
 Rubbing alcohol

1. Smell some vanilla extract. Continue to smell it until you no longer
sense the smell.
2. Place some rubbing alcohol under your nose. Observe the smell.

What’s Happening: The human body has a remarkable ability to get used to
odors we smell all the time. If the brain keeps getting the same message
from the nose, it will eventually learn to ignore it. This is important if you
are an animal that could be someone’s prey. If you’re a rabbit, for example,
you’ll get used to the normal smells around you and be able to sense if a
predator is coming. For humans, who don’t use our smell for survival, this
ability to block out smells isn’t all that helpful, and can actually be a
problem. Someone with bad body odor will get used to it, and won’t realize
they need a shower!

Experiment: Taste Bud Map

On your tongue are thousands of sensory neurons. These neurons are
organized into groups called taste buds. When you eat something, the taste
buds send a message to your brain. Your brain interprets the message, and
“tells” you what you are eating. Certain areas of the tongue have higher
concentrations of certain types of taste buds. In this experiment, you will
have a chance to see where they are.

Materials:

 3 cups
 Sugar water or punch
 Salt water
 Unsweetened iced coffee
 Q tips

1. Prepare a “sweet,” “salty,” “sour,” and “bitter” cup. In the “sweet”
cup, place sugar water or punch. In the “salty” cup place salt water.

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