Human olfactory receptors are true neurons extending from the nasal cavity and synapsing with neurons of the olfactory bulb of the brain. The olfactory receptors terminate in microvilli embedded with receptor molecules projecting into a thin mucus layer in the nasal cavity.

Read the following as if you were reading an MCAT passage. Practice slowing down to make nomenclature comprehensible:

The binding of a substance to a receptor molecule triggers a series of events in an olfactory receptor cell. The first event triggered is the elevation of the enzyme adenyl cyclase by G-protein which increases the level of cyclic AMP. The cyclic AMP then binds to transmembrane channels allowing the facilitated diffusion of Na+, causing a change in the state of cell polarization and a change against the baseline rate of impulse transmission. Similar to the send messenger system in endocrine signal amplification and transduction, the G-protein second messenger system is a common motif in sensory system signal transduction, being present in many sensory systems.

Imagine you were an MCAT writer. Can you think of a good question coming from this passage?












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