There are several important differences between the receptors of the nose and those of the mouth. Describe these receptors' differences in terms of their structure and function.
The receptors of the nose, specialized to detect chemicals with origins distant from the organism, are much more sensitive than taste receptors which are specialized to detect chemicals from sources inside the mouth. Olfactory receptor cells, located in the upper portion of the nasal cavity, are true neurons. Each receptor cell's dendrites reach to the surface of the nasal cavity's epithelial layer, in which the cell bodies of the receptors are embedded. At the epithelial lining's surface, the modified cilia of each receptor cell's dendrites protrude into the layer of mucus covering the epithelium and act as the receptor sites for chemical stimulation. The receptor cells transmit impulses to the olfactory bulb of the brain. In contrast, taste receptor cells or taste buds, located primarily on the upper surface of the tongue but also on the larynx and pharynx, are not neurons. The receptor cells have microvilli that are specialized to detect chemical presences; when stimulated, the receptor cells cause an impulse to be sent from very closely associated neuronal fibers. There are four types of taste receptor cells: those sensitive to sweet, to salt, to sour, and to bitter. Sweet and salt receptors are concentrated on the front of the tongue, sour receptors on the sides of the
