Your ability to smell comes from specialized sensory cells called olfactory sensory neurons. Smells reach the olfactory sensory neurons through your nostrils and a channel that connects the roof of the throat to the nose. The nasal cavities or nasal passages are wrinkled and protected by the mucosa.

Olfactory sensory neurons are found in a small patch of tissue high inside the nose. These cells connect directly to the brain. Each olfactory neuron has one odor receptor. Once the neurons detect molecules from the air, they send messages to your brain, where the smell is identified.

The sense of smell is one of the senses that take care of human safety. It helps us identify danger, for example.

Harmful substances produce smells that are perceived by us as unpleasant. This is why inedible food, faeces and smoke smell bad. By detecting harmful substances, the sense of smell keeps you away from potentially dangerous situations.

For the most part, the process of smelling takes place unconsciously. People can avoid some smells without even understanding why.

Smells are also said to have an effect on the development of human relationships. Indeed, the sense of smell often provides us with our first memories. A person can remember the smells they smelled when they were under the age of three when they are introduced to the particular smells again.