Scent Matching

We now know that odor molecules are diffused throughout a room by the motion of air molecules, which are constantly moving and bumping into them.  We also know that warm air moves faster than cold air, and that increasing the movement of the air (like with a fan) will increase the diffusion process.

In this experiment, we look at what happens when the odor molecules find their way into your nose. Your nose has smell cells located in a small area called the olfactory epithelium. We will use them here to match smells with other smells.

Here’s what you need

    • 10 small containers with lids
    • 10 cotton balls
    • 1 bottle of lemon juice
    • 1 cup of black coffee
    • 1 bottle of vanilla extract
    • 1 bottle of cinnamon oil
    • 1 bottle of soy sauce
    • 1 black felt marker
    • 1 assistant


 

Here’s what you do

  1. Take the lids off of the containers and number the first five with a 1 through 5. Mark the other five with A through E.
  2. Put a cotton ball into each container. Start with the numbered containers and add some lemon, coffee, cinnamon, soy sauce, and vanilla. Record the smell for each number for reference.
  3. Fill the lettered containers with the same liquids, but not in the same order. Be sure to record the material you have used for each letter.
  4. Take the closed containers to your assistant. Ask them to match the scent in the first canister with the proper lettered container without opening the container. Given them permission to roll, drop, and shake the containers, but they can’t be opened. Note their response – are they correct?
  5. Repeat step 4 for each of the containers until they all have been matched. Then check your recorded data and see how well your assistant did with matching.

What’s going on?

Everything here produces a distinct odor. The smells go into your nose where they are interpreted by the tiny hair-like smell cells in your olfactory epithelium. The smell cells work together to distinguish smells and then send the interpreted information to the brain for recognition.

We previously noted that humans have an average of 10,000,000 smell cells, but they aren’t all the same. You have about 20 different types and each detects a specific type of odor. The types work together and your brain translates their signals as a unique odor.

Exercises

  1. What is the scientific name for sense of smell?
  2. What is the name of the tissue which helps the brain to distinguish between smells?