Something smells funny Sense of smell - just like touching, hearing, tasting and seeing - has a lot to do with your brain.

First, what do you smell? A smell, or odor, is a chemical.

Second, how do you smell? When you smell, the chemicals from what you're smelling - say, a delicious orange freshly squeezed to make a cup of juice - reach your olfactory cells in your nose when you breathe them in from the air. The olfactory cells contain tiny hairs called cilia and are covered in a thin layer of slime, called olfactory mucus.

The olfactory cells detect the chemical and send a signal to a part of your brain called the thalamus and frontal lobe so they can be identified. Your brain tells you, "You are smelling an orange."

How does your brain know? Because your sense of smell is specific, it can tell between 4,000 and 10,000 smells.

Try This: Smells tasty Sense of smell is 75 percent of taste. Next time you're eating your favorite foods, try an experiment. Close your eyes and hold your nose. Then taste several things on your plate. Without peaking, can you tell what they are? How do they taste?

Write down your observations and try it again with something you don't like nearly as much such as Brussels sprouts. What do you notice this time?

Smelling contest
A human has 40 million olfactory receptor cells. A dog has 1 billion olfactory receptor cells and each is 100 times larger than a human's olfactory receptor cell.

No it Snot
What is that gooey stuff inside your nose? It's nasal mucus, commonly called, snot. It traps germs in the nose, acting as a protective slime barrier to keep you healthy. When you sneeze, the mucus and germs come out of your nose, so it's important to wash your hands every time you sneeze.