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NUTRITION EXAM #2 STUDY GUIDE DIETARY CARBOHYDRATES : organic compounds produced by plants via photosynthesis. Made up of C-H-O in the ratio of 1:2:1 SOURCES OF CARBS: -Wheat flour -broccoli -apple -peaches -rice -potatoes -oatmeal -pear -beans -corn -banana -nuts **Potatoes, beans and cereals are the 3 primary sources** CARBOHYDRATE CLASSIFICATION Simple Sugars (1-2 sugars) o Monosaccharides Glucose (blood sugar) *basic unit of polysaccharide Fructose (fruit sugar) Galactose (milk sugar) o Disaccharides Maltose (glucose+glucose) (malt sugar) Sucrose (glucose+fructose) (table sugar) Lactose (glucose+galactose) (milk sugar) Complex Carbs (>2 Sugars) o Oligosaccharides o Polysaccharides Starch (long chains of glucose molecules. How plants store glucose. Most starches are highly digestible by humans. Helical structure) Glycogen (highly branched molecule of glucose molecules. How humans store glucose in liver and muscle cells) Dietary Fiber (provide structure to plants. Made of all monosaccharides. Generally cant be digested by human enzymes) Soluble: dissolves in water. (oatbran, legumes, soybeans, fruits and vegetables). Insoluble: doesn’t dissolve in water (wheat bran and whole grains) Dietary Fiber cont…. Fiber digestion can occur in the large intestine. Gas, fatty acids, and vitamins can be produced. Fiber is important because it increases peristalsis, thus decreasing transit time through the gut (decreasing constipation and risk of diverticulitis) and keeps muscles strong (decreasing risk of diverticulosis) Average Fiber instake: 11-12 g/d Recommendations: 20-30 g/day. Cellulose : primary part of plant cell walls. Long chains of glucose molecules linked together that cannot be broken by human enzymes.
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CARBOHYDRATE DIGESTION *Goal: to end up with monosaccharides, because only monosaccharides can be absorbed. -Digestion begins in the mouth, stops in the stomach and continues in small intestine (lg intestine for Fiber) EX: Starch Digestion STEP I: Salivary Amylase in mouth digests starch into smaller polysaccharides called dextrins <5% of starches broken down here STEP 2: Pancreatic Amylase in small intestine digests dextrin to maltose STEP 3: Maltase (made in SI) breaks chemical bond of maltose into 2 glucose molecules Maltase digests maltose into 2 glucoses Sucrase digests sucrose into 1 glucose 1 fructose Lactase digests lactose into 1 glucose 1 galactose …Monosaccharides are absorbed at the small intestine via facilitated and active transport. …Monosaccharides transported away from SI via the blood and go to the liver via the portal vein. Lactose Intolerance: Inability of SI cells to produce adequate amounts of lactase
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