Chapter 15- Taste

Question 1

Taste

Answer 1

Sensations evoked by solutions in the mouth that contact receptors on the tongue and the roof of the mouth that then connect to axons in cranial nerves VII, IX, and X.

Question 2

Flavor

Answer 2

Flavor sensations are those produced by retronasal olfaction.

Question 3

Retronasal Olfactory Sensation

Answer 3

The sensation of an odorant that is perceived when chewing and swallowing force that odorant in the mouth up behind the palate into the nose. Such odor sensations are perceived as originating from the mouth, even though the actual contact of odorant and receptor occurs at the olfactory mucosa.

Question 4

Chorda Tympani

Answer 4

The branch of cranial nerve VII (the facial nerve) that carries taste information from the anterior, mobile tongue (the part that can be stuck out). The chords tympani exists the tongue with the lingual branch of the trigeminal nerve (cranial nerve V) and then passes through the middle ear on its way to the brain.

Question 5

Taste Bud

Answer 5

A globular cluster of cells that has the function of creating neural signals conveyed to the brain by the taste nerves. Some of the cells in a taste bud (receptor cells) have specialized sites on their apical projections that interact with taste stimuli. Receptor cells that mediate sourness form synapses with taste nerve fibers. Receptor cells that mediate sweetness and bitterness do not form synapses; rather, they communicate with nearby taste fibers chemically.

Question 6

Papilla

Answer 6

Any of multiple structures that give the tongue its bumpy appearance. From smallest to largest, the papilla types that contain taste buds are fungiform, foliate, and circumvallate. Filiform papillae are the smallest and most numerous but do not contain taste buds.

Question 7

Taste Receptor Cell

Answer 7

A cell within the taste bud that contains sites on its apical projections (microvilli) that can interact with taste stimuli. These sites fall into two major categories: those interacting with charged particles (e.g., sodium and hydrogen ions) and G protein-coupled receptors that interact with sweet and bitter stimuli.

Question 8

Filiform Papillae

Answer 8

Small structures on the tongue that provide most of the bumpy appearance. Filiform papillae have no taste function.

Question 9

Fungiform Papillae

Answer 9

Mushroom-shaped structures (maximum diameter 1 mm) that are distributed most densely on the edges of the tongue, especially the tip. Taste buds (an average of six per papilla) are buried in the surface.

Question 10

Supertasters

Answer 10

Those individuals whose perception of taste sensations is the most intense. A variety of factors may contribute to this heightened perception; including density of fungiform papillae.

Question 11

Foliate Papillae

Answer 11

Folds of tissue containing taste buds. Foliate papillae are located on the rear of the tongue lateral to the circumvallate papillae, where the tongue attaches to the mouth.

Question 12

Circumvallate Papillae

Answer 12

Circular structures that form an inverted V on the rear of the tongue (three to five on each side, with the largest in the center). Circumvallate papillae are mound-like structures, each surrounded by a trench (like a moat). They are much larger than fungiform papillae.

Question 13

Microvilli

Answer 13

Slender projections of the cell membrane on the tips of some taste bud cells that extend into the taste pore.

Question 14

Tastant

Answer 14

Any stimulus that can be tasted.

Question 15

Cranial Nerves

Answer 15

Twelve pairs of nerves (one for each side of the body) that originate in the brain stem and reach sense organs and muscles through openings in the skull.

Question 16

Insular Cortex

Answer 16

The primary cortical processing area for taste- the part of the cortex that first receives taste information. Also called the insula or the gustatory cortex.

Question 17

Orbitofrontal Cortex (OFC)

Answer 17

The part of the frontal lobe of the cortex that lies behind the bone (orbit) containing the eyes. It is involved in many functions and is responsible for the conscious experience of olfaction, as well as the integration of pleasure and displeasure from food, and has been referred to as the secondary olfactory cortex and secondary taste cortex. It is also critical for assigning affective value to stimuli- in other words, determining hedonic meaning.

Question 18

Basic Taste

Answer 18

Any of the four taste qualities that are generally agreed to describe human taste experience: sweet, salty, sour, bitter.

Question 19

Salty

Answer 19

One of the four basic tastes; the taste quality produced by the cations of salts (e.g., the sodium in sodium chloride produces the salty taste). Some cations also produce other taste qualities (e.g., potassium tastes bitter as well as salty). The purest salty taste is produced by sodium chloride (NaCl), common table salt.

Question 20

Sour

Answer 20

One of the four basic tastes; the taste quality produced by the hydrogen ion in acids.

Question 21

Bitter

Answer 21

One of the four basic tastes; the taste quality, generally considered unpleasant, produced by substances like quinine or caffeine.

Question 22

Sweet

Answer 22

One of the four basic tastes; the taste quality produced by some sugars, such as glucose, fructose, and sucrose. These three sugars are particularly biologically useful to us, and our sweet receptors are tuned to them. Some other compounds (e.g., saccharin, cyclamate, aspartame) are also sweet.

Question 23

Heterodimer

Answer 23

A chain of two molecules (a dimer) that are different from each other (hence hetero).

Question 24

Umami

Answer 24

The taste sensation produced by monosodium glutamate.

Question 25

Monosodium Glutamate (MSG)

Answer 25

The sodium salt of glutamic acid (an amino acid)

Question 26

Nontaster (of PTC/PROP)

Answer 26

An individual born with two recessive alleles for the TAS2R38 gene who experiences little or no taste from the compounds phenylthiocarbamide (PTC) and propylthiouracil (PROP).

Question 27

Taster (of PTC/PROP)

Answer 27

An individual born with one or two dominant alleles for the TAS2R38 gene and able to taste the compounds phenylthiocarbamide (PTC) and propylthiouracil (PROP). PTC/PROP tasters who also have a high density of fungiform papillae tend to be PROP supertasters.

Question 28

Cross-Modality Matching

Answer 28

The ability to match the intensities of sensations that come from different sensory modalities. This ability allows insight into sensory differences. For example, a listener might adjust the brightness of a light until it matches the loudness of a tone.

Question 29

Specific Hungers Theory

Answer 29

The idea that deficiency of a given nutrient produces craving (a specific hunger) for that nutrient. Curt Richter first proposed this theory and demonstrated that cravings for salty or sweet are associated with deficiencies in those substances. However, the idea proved wrong for other nutrients (e.g., vitamins).

Question 30

Labeled Lines

Answer 30

A theory of taste coding in which each taste nerve fiber carries a particular taste quality. Thus a fiber that responds best to sucrose but also responds with small responses to other stimuli mediates only sweet sensations.