When you have a cold and your nose is blocked, you will notice that your food does not seem to have much flavor. That is because the upper part of the nose is not clear to receive the chemicals that trigger the olfactory receptors and send messages to the brain. Try holding your nose the next time you eat something. You will notice that your taste buds are able to tell your brain something about what you are eating---that it is sweet, for instance---but you will not be able to pick the exact flavor until you let go of your nose.