What is the smelling of fluid in alveoli and branchioles?

The smelling of fluid in alveoli and branchioles is known as olfaction. Olfaction is the process of detecting and identifying odours. The olfactory receptors are located in the olfactory epithelium, which is a specialised region of the nasal cavity. When an odour molecule binds to an olfactory receptor, it triggers a signal that is transmitted to the brain, where it is interpreted as a smell.