• Question: How can people smell?

    Asked by Kizzy to Chloe, Irene, Pierre, NULL, Uday on 13 Nov 2015.
    • Photo: Chloe Huseyin

      Chloe Huseyin answered on 13 Nov 2015:

      In order for you to smell something, molecules from the source of the smell have to make it to your nose. That means that everything you can smell is giving off molecules. Those molecules are generally light and volatile (easy to evaporate) chemicals that float through the air and into your nose.

      At the top of your nasal passages behind your nose, there is a patch of special neurons (nerve cells) about the size of a postage stamp. These neurons are unique in that they are out in the open where they can come into contact with the air (unlike the ones inside the skin on your hands that tell if something is hot or cold). They have hair-like projections called cilia that increase their surface area. An odour molecule binds to these cilia to trigger the neuron and cause you to perceive a smell.

    • Photo: Irene Regan

      Irene Regan answered on 13 Nov 2015:

      Hi 🙂
      The nose has special cells which help us smell.

      The smells of a rose, perfume, freshly baked bread and cookies…these smells are all made possible because of your nose and brain.
      The sense of smell, called olfaction,is the detection and perception of chemicals floating in the air.
      Chemical molecules enter the nose and dissolve in mucous within a membrane called the olfactory epithelium.
      In humans, the olfactory epithelium is located about 7 cm up and into the nose from the nostrils.

      Your nose can help detect dangerous chemicals in the air.

      The human nose can smell many different odours but is far less sensitive than other animals such as dogs.

    • Photo: NULL

      NULL answered on 17 Nov 2015:

      When they don’t shower! (joking…)

      The cells in our nose are really special, they use a whole set of different proteins that can each detect a different smell (a different chemical). Taste works in a similar way. There are so many of these different proteins, and a different gene makes each one.

      We have about 25,000 genes in total that make our cells, our bones, our brains, our whole bodies, and nearly a thousand of those genes are just for smelling!

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