carbohydrates
compounds composed of carbon, oxygen, and hydrogen arranged as monosaccharides. Most, but not all, have a ratio of one carbon molecule to one water molecule (CH2O)n
monosaccharides
single sugars, (C6H12O6), glucose, fructose, and galactose
disaccharides
sugars composed of pairs of monosaccharides linked together; maltose, sucrose, lactose
polysaccharides
compounds composed of many monosaccharides linked together. Three types are important in nutrition: glycogen, starches, and (dietary) fibers
simple carbohydrates
monosaccharides and disaccharides (the sugars) are sometimes called this
complex carbohydrates
polysaccharides (starches and fibers) are sometimes called this
maltose
disaccharide; glucose + glucose. Produced whenever starch breaks down-as happens in human beings during carbohydrate digestion. Also occurs during the fermentation process that yields alcohol. Minor constituent of a few foods
sucrose
disaccharide; glucose + fructose. Because the fructose is accessible to the taste receptors, it tastes sweet, accounting for some of the natural sweetness of fruits, vegetables, and grains
lactose
disaccharide; glucose + galactose. Principle carbohydrate of milk. Known as milk sugar, contributes half of the energy (calories) provided by fat-free milk
glucose
monosaccharide; commonly known as a blood sugar, serves as an essential energy for all the body's activities. One of the 2 sugars in every disaccharide and unit from which the polysaccharides are made almost exclusively.
starch
polysaccharide; chief food source of energy for all the world's people. Storage form of energy in plants. Plant cells store glucose as this-long branched or unbranched chains of hundreds of thousands of glucose molecules linked together. When you eat plan
glycogen
polysaccharide; an important storage form of energy in the body. An animal polysaccharide composed of glucose; manufactured and stored in the liver and muscles as a storage form of glucose. Not significant food source of carbohydrate and is not counted as
fructose
monosaccharide; sweetest of the sugars. Same chemical formula as glucose-C6H12O6-but its structure differs. Arrangement of atoms stimulates the taste buds on the tongue to produce the sweet sensation. Found abundantly in fruits, honey, and saps. (soluble
galactose
monosaccharide; part of the disaccharide lactose
condensation
a chemical reaction in which water is released as two reactants combine to form one larger product
hydrolysis
reaction that splits a molecule into two, with H added to one and OH to the other (from water); break down molecules during digestion
fiber
polysaccharide; provide structure in stems, trunks, roots, leaves, and skins of plants. Composed of a variety of monosaccharides and other carbohydrate derivatives
dietary fibers
structural parts of plants and thus are found in all plant-derived food-vegetables, fruits, whole grains, and legumes. Bonds between their monosaccharides cannot be broken down by digestive enzymes in the body. For this reason often described as non starc
soluble fibers
nonstarch polysaccharides that dissolve in water to form a gel. An example is pectin from fruit, which is used to thicken jellies. Commonly found in oats, barley, legumes, and citrus fruits, associated with protecting against heart disease and diabetes by
fermentable
extent to which bacteria in the GI tract can break down fibers to fragments that the body can use
insoluble fibers
nonstarch polysaccharides that do not dissolve in water. Examples include the tough, fibrous structures found in the strings of celery and the skins of corn kernels. Found mostly in whole grains (bran) and vegetables, promote bowel movements, alleviate co
vicious
a gel-like consistency
phytic acid
not a dietary fiber, but is often found in the same foods. A non nutrient component of plant seeds. Also occurs in the husks of grains, legumes, and seeds and is capable of binding minerals such as zinc, iron, calcium, magnesium, and copper in insoluble c
amylase
an enzyme that hydrolyzes amylose (a form of starch). It is a carbohydrase, an enzyme that breaks down carbohydrates
satiety
feeling of fullness and satisfaction that occurs after a meal and inhibits eating until the next meal. Determines how much time passes between meals
small intestine
performs most of the work of carbohydrate digestion. Nutrient absorption takes place here
pancreatic amylase
a major carbohydrate-digesting enzyme that enters the intestine via the pancreatic duct and continues breaking down the polysaccharides to shorter glucose chains and maltose
maltase
breaks maltose into 2 glucose molecules
sucrase
breaks sucrose into one glucose and one fructose molecule
lactase
breaks lactose into one glucose and one galactose molecule
available carbohydrates
starches and sugars are called this because human digestive enzymes break them down for the body's use
unavailable carbohydrates
fibers are called this because human digestive enzymes cannot break their bonds
lactose intolerance
a condition that results from inability to digest the milk sugar lactose; characterized by bloating, gas, abdominal discomfort, and diarrhea. Undigested lactose becomes food for intestinal bacteria, which multiply and produce irritating acid and gas, furt
lactase deficiency
a lack of the enzyme required to digest the disaccharide lactose into its component monosaccharides (glucose and galactose)
gluconeogenesis
conversion of protein to glucose, the making of new glucose. Making of glucose from a noncarbohydrate source
protein-sparing action
action of carbohydrate (and fat) in providing energy that allows protein to be used for other purposes
ketone bodies
metabolic products of the incomplete breakdown of fat when glucose is not available. Provide an alternate fuel source during starvation
ketosis
an undesirably high concentration of ketone bodies in the blood and urine
acid-base balance
equilibrium in the body between acid and base concentrations. Because most ketone bodies are acidic, ketosis disturbs the body's normal...
homeostasis
maintenance of constant internal conditions by the body's control systems. Regulated primarily by 2 hormones: insulin and glucagon
insulin
moves glucose from the blood into the cells; a hormone secreted by special cells in the pancreas in response to increased blood glucose concentration. Primary role is to control the transport of glucose from the bloodstream into the muscle and fat cells
glucagon
brings glucose out of storage when necessary; a hormone that is secreted by special cells in the pancreas in response to low blood glucose concentration and elicits release of glucose from liver glycogen stores
epinephrine
a hormone of the adrenal gland that modulates the stress response; formerly called adrenaline. Signals the liver cells to release glucose is this "fight-or-flight" hormone. Works to release glucose from liver glycogen to the blood
diabetes
a chronic disorder of carbohydrate metabolism, usually resulting from insufficient or ineffective insulin. Blood glucose is central
type 1 diabetes
less common type of diabetes in which the pancreas fails to produce insulin
type 2 diabetes
more common type of diabetes in which the cells fail to respond to insulin. High-fiber foods, especially whole grains, play a key role in reducing this
hypoglycemia
an abnormally low blood glucose concentration; weakness, rapid heartbeat, sweating, anxiety, hunger, and trembling. Most commonly is a consequence of poorly managed diabetes: too much insulin, strenuous physical activity, inadequate food intake, or illnes
glycemic response
extent to which a food raises the blood glucose concentration and elicits an insulin response
glycemic index
a method of classifying foods according to their potential for raising blood glucose. Some studies have shown that selecting foods that is ranked low is a practical way to improve glucose control
added sugars
sugars and syrups used as an ingredient in the processing and preparation of foods such as breads, cakes, beverages, jellies, and ice cream as well as sugars eaten separately or added to food at the table
dental caries
sugars from foods and from the breakdown of starches in the mouth can contribute to this. Bacteria in the mouth ferment the sugars and, in the process, produce an acid that erodes tooth enamel causing this or tooth decay
dental plaque
a gummy mass of bacteria that grows on bacteria and can lead to dental caries and gum disease.
cellulose
an insoluble fiber (as in cereal brans, fruits, and vegetables)