mitral

Meaning: Mitral cells are second-order neurons in the olfactory bulb. Olfactory receptor neurons in the nasal epithelium send axons through the cribriform plate and synapse on mitral cells in clusters called glomeruli. Mitral cell axons then form the olfactory tract, which projects to the olfactory cortex, amygdala and other limbic regions. In Biology, "mitral" also names the valve between the left atrium and left ventricle.

On the MCAT: Sensation passages ask you to trace the smell pathway in order: odorant binds a G protein-coupled receptor on cilia → olfactory receptor neuron → glomerulus → mitral cell → olfactory tract → cortex and limbic system. A common question asks why smells trigger vivid memories and emotions. The answer is the direct route to the amygdala and hippocampus, and olfaction, unlike most senses, reaches cortex without a thalamic relay first. Another question gives a head injury that shears axons at the cribriform plate and asks which sense is lost (smell), because receptor axons can no longer reach mitral cells.

Common confusion: Mitral cells are not the receptor cells. The olfactory receptor neurons detect odorants; mitral cells relay the signal onward. Do not confuse the cells with the mitral valve, which belongs to the heart.