Explain the Olfactory receptors
In the section on taste receptors earlier, we learnt that there is a regional distribution of taste buds for primary taste sensations like sweet, salt, sour and bitter, whereas olfactory neurons are not specialized to detect single fundamental odours. Same receptors may respond vigorously to some stimulus molecules, weakly to several others and not at all to others. Subsequently, the olfactory system can mediate a large number of different odour sensations. For stimulation of olfactory receptors, molecules must dissolve in the mucus before causing stimulation, whereas, there is a direct interaction between taste receptors and molecules.
Afferent information from the taste buds is relayed directly to specific location near the mouth region of somatosensory cortex by way of the brainstem and thalamus whereas the central afferents of olfaction split into two. The first one involves limbic system, which influences sex, emotion, feeding and visceral homeostasis. It is possible that olfactory signals process along this route, influence moods and behaviour without entering conscious awareness. The second route leads to olfactory cortex. Connection between the olfactory cortex and other sensory regions of the cortex allow integration of olfactory sensations with those arising from other sensory modalities. Signals that are processed along this route are more likely to lead to conscious sensation.