Flashcards in Nutrition Deck (140)
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31
Segmentation
A periodic squeezing or partitioning of the intestine at intervals along its length by its circular muscles.
32
Reflux
A backward flow.
re = back
flux = flow
33
Enzymes
Facilitate the making and breaking of bonds in chemical reactions. The enzyme itself is a catalyst that remains unchanged.
34
Hormones
Act as chemical messengers, sometimes regulating enzyme action.
35
-ase
A word ending denoting an enzyme. The word beginning often identifies the compounds the enzyme works on.
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Carbohydrase
An enzyme that hydrolyzes carbohydrates.
37
Lipase
An enzyme the hydrolyzes lipids (fats).
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Protease
An enzyme that hydrolyzes proteins.
39
Digestive enzymes
Proteins found in digestive juices that act on food substances, causing them to break down into simpler compounds.
The enzymes involved in digestion facilitate a chemical reaction known as hydrolysis.
40
Hydrolysis
A chemical reaction in which a major reactant is split into two products, with the addition of a hydrogen atom (H) to one and a hydroxyl group (OH) to the other (from water, H2O). (The noun is hydrolysis, the verb is hydrolyze.)
The addition of water to break a molecule into smaller pieces. Breaks a disaccharide in two, with H added to one and OH to the other. Commonly occurs during digestion.
hydro = water
lysis = breaking
41
The breakdown of food into nutrients requires secretions from five different organs:
• The salivary glands
• The stomach
• The pancreas
• The liver (via the gallbladder)
• The small intestine
42
Catalyst
A compound that facilitates chemical reactions without itself being changed in the process.
43
pH
The unit of measure expressing a substance's acidity or alkalinity.
44
Glands
Cells or groups of cells that secrete materials for special uses in the body.
45
Exocrine glands
Secrete their materials "out" (into the digestive tract or onto the surface of the skin).
exo = outside
krine = to separate
46
Endocrine glands
Secrete their materials "in" (into the blood).
endo = inside
krine = to separate
47
Salivary glands
Exocrine glands that secrete saliva into the mouth.
48
Saliva
The secretion of the salivary glands. Its principal enzyme begins carbohydrate digestion.
49
Gastric glands
Exocrine glands in the stomach wall that secrete gastric juice into the stomach.
gastro = stomach
50
Gastric juice
The digestive secretion of the gastric glands of the stomach.
51
Hydrochloric acid
A acid composed of hydrogen and chloride atoms (HCI) that is normally produced by the gastric glands.
52
Mucus
A slippery substance secreted by the cells of the GI lining (and other body linings) that protects the cells from exposure to digestive juices )and other destructive agents). The lining of the GI tract with its coat of mucus is a mucous membrane.
53
Liver
The organ that manufactures bile. It is the first to receive the nutrients absorbed from the GI tract and prepares them for use by the body. It is the body's major metabolic organ. Detoxifies substances that might cause harm and prepares waste products for excretion.
Stores about 1/3 of the body's glycogen and releases glucose into the bloodstream as needed.
54
Bile
An emulsifier that prepares fats and oils for digestion; an exocrine secretion made by the liver, stored in the gallbladder, and released into the small intestine when needed.
It brings fats into suspension in water so that the enzymes can break them down into their component parts.
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Emulsifier
A substance with both water-soluble and fat-soluble portions that promotes the mixing of oils and fats in a watery solution.
56
Pancreatic juice
The exocrine secretion of the pancreas, containing enzymes for the digestion of carbohydrate, fat, and protein as well as bicarbonate, a neutralizing agent. The juice flows from the pancreas into the small intestine through the pancreatic duct. (The pancreas also has an endocrine function, the secretion of insulin and other hormones.)
57
Bicarbonate
An alkaline compound with the formula HCO3 that is secreted from the pancreas as part of the pancreatic juice. (Bicarbonate is also produced in all cell fluids from the dissociation of carbonic acid to help maintain the body's acid-base balance.)
58
Villi
Finger-like projections from the fold of the small intestine. (The singular is villus.)
59
Microvilli
Tiny, hairlike projections on each cell of every villus that can trap nutrient particles and transport them into the cells. (The singular is microvillus.)
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