Physiology, Taste

The human body is capable of perceiving five traditional senses: hearing, sight, smell, touch, and taste. Also known as gustation, the sense of taste is essential in discerning the characteristics of substances that one ingests. At a basic evolutionary level, taste allows one to assess whether ingested substances are nutritious or potentially hazardous. This sensation is primarily relayed via receptors located on the tongue. However, at a higher cortical level, taste is considered a multisensory experience as smell, texture, and activation of specific receptors (eg, pain receptors from spicy food) all play a role in determining how something "tastes."  A fundamental working knowledge of the anatomy of the tongue is important in fully understanding the concept of taste. The human tongue is divided into an anterior two-thirds and a posterior one-third, separated by a v-shaped groove called the sulcus terminalis. The dorsal aspect of the tongue is covered with bumps known as papillae, of which there are four types: circumvallate, fungiform, foliate, and filiform. The circumvallate, fungiform, and foliate papillae contain taste buds known as gustatory papillae. Taste buds are found on the tongue and the pharynx, larynx, soft palate, and epiglottis. The circumvallate papillae are on the distal aspect of the anterior two-thirds of the tongue and are most sensitive to bitter tastes. The fungiform papillae are found on the tip of the tongue and are most sensitive to sweet and savory (umami) tastes. The foliate papillae are found on the sides of the tongue and are most sensitive to salty and sour tastes. Filiform papillae are found throughout the entire surface of the dorsal tongue and do not contain taste buds. The rough texture of the filiform papillae aid in the gripping of food and transfer down to the esophagus, as well as in the cleaning of the mouth and spreading of saliva.