Gustatory System

Presented by Lim, Erynne

Nguyen, Cynthia

 the sensory system for the sense of taste

Structure of the Human Tongue

OThe tongue has 4 kinds of papillae:-papillae: one of the small, round, or cone-shaped protuberances on the top of the tongue that contain taste buds

1. foliate papilla: a series of folds on the sides of the tongue in the back2. circumvallate papilla: organized in an inverted V at the back of tongue3. fungiform papilla: found scattered across the top front and middle4. filiform papilla: found across the top

Taste BudsOThe circumvallate, foliate, and fungiform

papillae contain taste buds while the filiform papilla doesn’t- taste buds: smallest functional of taste; is found on tongue, back of throat and roof of mouth

OTaste buds contains several taste receptor cells- taste receptors: a type of receptor which facilitates the sensation of taste

OAn average person contains 5,000 taste buds!

Types of Basic TasteOThere are 5 different basic tastes:

-Bitter-Salty-Sour-Sweet-Umami

-In humans, the different types of taste cells are scattered throughout the tongue. >A common misconception tastes are found in separate regions of the tongue.

O Spicy is not a type of basic taste because the sensation doesn’t arise from taste buds-It is the reaction when temperature fibers & nociceptors/pain in the tongue is stimulated-Capsaicin is the active ingredient

Taste: BitterO Bitter: having a sharp, pungent taste or smell

-ex: coffee, beer, medicine, poison, etc.

OThe bitterness serves as an important protective function against recognition of toxic compounds

Taste: SaltyOSalty: tasting of, containing, or preserved

with salt-ex: table salt, pretzels, etc.

OSaltiness is tasted when there is a presence of cations-ex: Li+, K+, and most commonly Na+

Taste: SourOSour: having an acid taste like lemon or

vinegar-ex: lemon/lime, wine, spoiled milk, some candies, etc.

OLarge quantities of sour food, containing acids, will lead to irreversible tissue damage

Taste: SweetOSweet: having the pleasant taste

characteristic of sugar or honey-ex: sugar, candy, cake, ice cream, etc.

OTasted when there is a strong presence of glucose

Taste: UmamiOUmami: the meaty or savory taste of

glutamate proteins or other similar compounds-ex: cheese, soy sauce, etc.

OContains monosodium glutamate and L-glutamate

ORecently added as a 5th taste!

Brain tastes the tasteOWhen the nerve fibers are stimulated, they

send messages through three specialized taste nerves to the brain, where specific tastes are identified

-Microvilli(nerve fibers): each of a large number of minute projections from the surface of some cells-The facial nerve (VII)- the anterior two thirds of the tongue-The glossopharyngeal nerve(IX)- the posterior one third of the tongue-A branch of the vagus nerve (X)- the back of the oral cavity.

- taste compounds: interact with the tops of these specialized cells which then transmit taste information through the nerve to the brain

Taste DisordersO Brain damage can lead to loss of tasteO Common taste disorders:

O Phantom taste perception: a lingering, often unpleasant taste even though you have nothing in your mouth

O Hypogeusia: a reduced ability to taste the 5 basic tastes (sweet, sour, bitter, salty, and umami)

O Ageusia: cannot detect any tastes>Complete loss of taste is very rare.

Bibliography

Internethttp://www.nidcd.nih.gov/health/smelltaste/pages/taste.aspxhttp://www.medicinenet.com/taste_disorders/page2.htmhttp://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Taste.htmlBookBiology Textbook. McGraw-Hill