Sense of Smell and Smelling - How Do We Smell?

How do we smell?  Terrible!!!  But all jokes aside, the sense of smell is a very important function.

Olfaction, or smelling, is the sense that allows us to distinguish scents.

When we breathe in through the nose, we inhale airborne molecules.

Inside your nose, about 3 inches (7 cm) above and behind your nostrils, is an area 1 inch wide and 2 inches (2 x 5 cm) long. This is where the receptors that sense smell are located. They are called olfactory receptors, and are very sensitive.

Hanging from each of these receptors are tiny hairs called cilia, each covered with mucus. These catch samples of the molecules we inhale. Odorant molecules (those we can smell) are dissolved and bind to the olfactory receptors, stimulating them (each receptor is designed to receive one specific odor only). They then send the information by electrical impulses along the olfactory nerve to the brain.

The signals are received by several areas of the brain. These areas include the piriform cortex, where smells are mainly identified, the medial amygdala, which is involved with social functions, and the entohinal cortex, which is a memory center. Smells are often a strong trigger of memories and emotions.

Your sense of smell is ten thousand times stronger than your sense of taste, and smell helps to enhance flavors. Smell is also important as a warning system, alerting us to potential dangers such as smoke or spoiled food.

How Olfaction Works

Classification of Odors

There have been a number of theories about types of odors, and whether they can be classified.  As yet, no attempt at classifying odors has been universally accepted.

One Classification of Smells

Endoscopic trip through the nasal cavity.

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