Post on 24-Dec-2015
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