Smell

Watch a video

The olfactory system, or the sense of smell, is one of the five special senses. It’s a sensory system that detects and processes chemical stimuli, known as odorants. The sense of smell plays an important role in memory, emotions and even survival by influencing our interactions with the environment.

The process of smelling starts in the nasal cavity where specialized sensory neurons transduce chemical stimuli into electrical signals. These neurons are modified bipolar neurons that detect odorants via their olfactory cilia. Besides the above olfactory sensory neurons, the nasal cavity also contains supporting epithelial cells and basal cells, which protect and support the sensory neurons. The axons of the olfactory sensory neurons pass through the cribriform plate of the ethmoid bone as bundles of axons and terminate in the olfactory bulb. In the olfactory bulb, the aforementioned axons synapse with mitral and tufted cells, which are the main projection cells that are responsible for relaying olfactory signals to the brain. The axons of these cells form the olfactory tract, which travels to various cortical areas, including the piriform cortex, amygdala, entorhinal cortex, hippocampus and hypothalamus. All these cortical areas are responsible for conscious odor perception, as well as for producing emotional and visceral responses based on past experiences.

Watch the video below and learn all the details about the sense of smell from the transduction of the chemical stimuli to electric signals in the nasal cavity to the cortical areas that are responsible for this special sense.

Explore concepts

Mechanisms of Olfactory Transduction

The process of detecting and converting odorants into electrical impulses involves several steps and starts from the olfactory sensory neurons in the nasal cavity.

Pathway of smell

Take a look at our image gallery below to see and identify all the structures that are relevant to this pathway.

Take a quiz

Test your knowledge on the physiology of smell withe the following quiz!

Summary