「植物看得見你」公開課筆記／3.2 Mechanism of a Receptor

We all can smell things going in the air. What is happening is that there's a volatile chemical -- these molecules diffusing into the air, goes into our nose, somehow send a signal through the rest of the nervous system up to the brain to the brain, that we translate into a type of smell, whether it be a pleasant smell or an unpleasant smell.

Now we know quite a bit about how we smell thanks to some groundbreaking work by Richard Axel and Linda Buck, for which they got the Nobel Prize in 2004. Now the mechanism that allows us to smell is that there are receptors up in the nose that can bind these small molecules. Each chemical has its own shape. Within the cells in our noses, there are receptors that can bind each specific chemical. They send an electric signal to the brain that says this particular chemical was now sensed.

So this is different from light, we only need four different types of receptors to see red, green, blue, black and white light. Here, we need hundreds of different receptors to get all of the different smells.

In each of the chemoreceptor cells, in each of the cells in our nose that sense a volatile chemical, there are receptors in their membranes and each of these receptors is specific for one chemical. We have hundreds of different cells, each specific for one volatile chemical.

Most smells are not just one chemical, they're a bouquet of smells, which is why we can describe things like wine in many different ways.