19.2
The Tongue and Taste Buds
The surface of the tongue is covered with various small bumps called papillae, which either distribute what has been ingested (filiform papillae) or c…
The surface of our tongue is covered in hundreds of tiny bumps called papillae. One type, filiform, simply provides the friction needed to move food around.
Within other papillae—fungiform, circumvallate, and foliate—are numerous taste buds—clusters of gustatory cells. Each papilla increases the surface area, which is important for taste intensity.
At the very tip of every taste bud, protruding through a pore, are microvilli—hair-like extensions that contain different chemoreceptors.
When dissolved molecules called tastants bind to specific receptors, the cell is stimulated and activates nearby nerve endings. The nerves then pass the signal on to the brain for a particular perception of flavor.
View the full transcript and gain access to JoVE Core videos
Q1: What are papillae and what role do they play in taste?
Papillae are tiny bumps covering the tongue's surface. Filiform papillae provide friction to move food, while fungiform, circumvallate, and foliate papillae contain taste buds—clusters of gustatory cells. These papillae increase surface area, enhancing taste intensity and allowing the sensory system and perception of flavor.
Q2: How do taste buds detect flavor molecules?
Taste buds contain 30 to 100 gustatory receptor cells with microvilli extending into the taste pore. When dissolved tastant molecules bind to specific chemoreceptors on these microvilli, the cells are stimulated. This activation triggers nearby nerve endings to send signals to the brain, creating flavor perception.
Q3: Where are different types of taste papillae located on the tongue?
Fungiform papillae, the most numerous type, occupy the anterior two-thirds of the tongue and contain one to eight taste buds each. Circumvallate papillae, the largest type, are positioned at the back in a V-shaped formation. Foliate papillae are located on the tongue's sides and contain over 100 taste buds per papilla.
Q4: How many taste buds does the average person have?
The average number of taste buds varies significantly among individuals, ranging from 2,000 to 10,000. Each taste bud contains gustatory cells at different developmental stages. Taste cells have a lifespan of approximately 10 to 14 days and are continually replaced throughout life.
Q5: Is the tongue's taste map accurate for detecting different flavors?
No. Scientific research by Collings, Yanagisawa, and colleagues demonstrates that the five basic tastes can be perceived anywhere across the tongue. Distinct tastes are not restricted to particular regions, contrary to the traditional tongue taste map commonly shown in textbooks.
Q6: What are microvilli and why are they important for taste?
Microvilli are hair-like extensions protruding from gustatory cells through the taste pore. They contain different chemoreceptors that bind to tastant molecules. This binding stimulates the gustatory cells and activates nerve endings, enabling the brain to process and interpret flavor signals.
Q7: How does the tongue's surface structure enhance taste perception?
The tongue's papillae increase surface area, which is critical for taste intensity. By housing taste buds within fungiform, circumvallate, and foliate papillae, the tongue maximizes contact between tastant molecules and gustatory receptor cells. This structural design allows for efficient detection and transmission of flavor information to the brain.