27/07/2020
How are smells made?
A smell is created when a substance releases molecules (particles) into the air. For us to detect the smell, those molecules need to enter our nose.
The more volatile the substance is (the more easily it gives off molecules), the stronger its smell. Non-volatile objects, such as steel, donβt have much, if any, smell at all.
How do smells travel through the air?
Smells travel through the air by a process called diffusion; air particles, and the odour particles within the air, move freely in all directions. They are constantly moving and eventually they spread out through the air around them.
How do we detect smells?
Once the odour particles enter our nostrils they are detected by olfactory receptors near the back of our nose. These receptors then send signals to an area of the brain called the olfactory bulb and the chemical composition of the mix of odours it determined. What is really interesting is that the smell detection pathway within the brain also connects to the amygdala and hippocampus, areas connected with emotion and memory. Smells can literally change how we feel or help us make connections and lay down memories.
Some people have no sense of smell, or they lose it during their lifetime. This is called anosmia. When we lose our sense of smell it can have a big impact on our psychological wellbeing.