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84 Cards in this Set
- Front
- Back
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6 essential nutrients |
-Carbohydrates -Protein -Fat -Vitamins -Minerals -Water |
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Carbs |
-Primary source of fuel for heat and energy -Maintain bodys backup storage of quick energy as glycogen -Should provide 45-65% of total kilocalories |
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Fats |
-Animal and plant sources -Secondary (storage) form of heat and energy -Should provide no more than 20-35% of total kilocalories |
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Proteins |
-Primary function tissue building -Should provide 10-35% of total kilocalories -Source of energy when supply from carbohydrates and fats is insufficient |
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DRIs |
Dietary Reference Intake -National Academy of Sciences sets since 1941 -Recommended Dietary Allowances (RDAs) -US and Canadian scientists developed DRIs -Includes recommendations for gender and age group |
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RDA |
Recommended Dietary Allowance -Daily intake of nutrients that meet needs of almost all healthy individuals |
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EAR |
Estimated Average Requirement -Intake level that meets needs of half the individuals in a specific group |
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AI |
Adequate Intake -Used when not enough evidence to establish the RDA |
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UL |
Tolerable Upper Intake Level -Sets maximal intake unlikely to pose adverse health risks |
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Carbs (Relation to energy) |
-basic fuel source -energy production system -dietary importance |
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Monosaccharides (single sugar, simple carb) |
Glucose: basic single sugar in human metabolism Fructose: primarily found in fruits and honey Galactose: product of lactose digestion |
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Disaccharides (double sugar, simple carb) |
Sucrose: common table sugar Lactose: sugar found in milk Maltose: product of intermediate breakdown of starch by the body |
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Polysaccharides (complex carb) |
Composed of many single sugar units Starch: most significant polysaccharides Glycogen: formed within body tissues; crucial Dietary fiber: important dietary assets |
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Dietary fiber |
Whole grains, legumes, vegetables, fruits with as much skin remaining as possible Recommended daily intake for men age 50 and younger: 38g/day For women: 25g/day |
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Cellulose |
Chief component of cell walls in plants |
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Lignin |
-Only noncarbohydrate dietary fiber -Large compound, forms woody part of some plants |
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Noncellulose polysaccharides |
-Absorb water and swell to larger size, slowing stomach emptying -Bind with bile acids -Provide bulk for normal muscle action |
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Nutritive Sweeteners |
Sugar alcohols (sortibol, mannitol, xylitol) |
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Nonnutritive Sweeteners |
Artificial sweeteners in food |
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Basic fuel supply (carbs) |
-physical activities -work of body cells |
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Reserve fuel supply (carbs) |
-Liver stores about 100g of glycogen -Muscle stores 300-400g -Maintains blood glucose level |
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Special tissue functions (carbs) |
-Liver: glycogen reserves maintain overall energy balance -Carbohydrate protects protein and fat supply -Central nervous system depends on constant carb supply |
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Starches |
-Most important carb in the diet -Whole grain starches such as rice, wheat, corn, potatoes |
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Sugars |
-Not necessarily bad -Added sugars provide empty calories -Moderation is key |
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Mouth |
-Mechanical or muscle functions break food mass into smaller particles -Chemical process in which enzymes begin breaking food down |
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Stomach |
-Peristalsis continues mechanical breakdown -Gastric secretions continue chemical breakdown of nutrients -Secretions do not break down carbs but stop action of salivary amylase |
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Small intestine |
-Peristalsis continues mechanical breakdown of food -Enzymes from pancreas and intestine continue chemical breakdown |
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Pancreatic secretions |
-Enter duodenum through common bile duct -Contain pancreatic amylase to continue breakdown of starch |
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Intestinal secretions |
-Three disaccharides: sucrose, lactose, maltase -Render disaccharides into monosaccharides |
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Dietary Reference Intakes (carbs) |
-45 to 65% of adults total caloric intake should come from carbohydrate foods -Limit sugar to no more than 25% of calories consumed |
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Fat in foods provides |
-Energy -Essential nutrients -Flavor and satisfaction -Fat substitutes are not absorbed and therefore do not provide energy or essential nutrients but may provide flavor and satisfaction |
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Adipose tissue |
-protects organs -helps regular temperature |
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Cell membrane structure |
-forms part of cell membrane -helps transport nutrients across cell membranes |
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Digestion of fats |
Mouth Stomach Small intestine -bile from the gallbladder -enzymes from the pancreas -enzymes from the small intestine -absorption |
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Dietary important of fats |
Concentrated fuel for energy |
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Classes of fats |
Lipids Glycerides -Triglycerides Fatty Acids Lipoproteins |
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Saturated fatty acids |
Filled or "saturated" with hydrogen |
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Unsaturated fatty acids |
-Not completely filled with hydrogen -Less heavy, less dense -Monosaturated: one unfilled spot -Polyunsaturated: two or more unfilled spots |
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Trans-fatty acid |
-naturally occuring -hydrogen atoms around carbon double bond are on opposite sides -negative health consequences, cardiovascular disease |
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Omega 3 and omega 6 fatty acids |
Determined by position of first carbon involved in double bond |
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Essentiality of fatty acids |
Definition of essential -Absence will create specific deficiency -Body can create it |
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Two essential fatty acids |
Linoleic Alpha-linoleic |
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Food sources of fat |
Animal fats Plant fats |
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Characteristics of food fat sources |
Visible fats Invisible fats |
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Food label information |
Calories from fat Calories from saturated fat Total fat Saturated fat Polyunsaturated fat Monounsaturated fat Cholesterol Voluntary information |
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Dietary fat and health |
-The american diet is high in fat -excess calories are stored as fat -animal food sources contribute to excess cholesterol and saturated fat in the diet -a decrease in saturated fat reduces serum total cholesterol -monounsaturated fats reduce LDL cholesterol when substituted for saturated fat |
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HDL cholesterol |
Good cholesterol Happy = HDL |
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LDL cholesterol |
Bad cholesterol Lousy = LDL |
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Diet ratio |
Current US diet at ratio of 8:1 to 12:1 Recommended ratio of 2:1 to 3:1 |
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Recommended fat levels |
Recommend that the fat content should not exceed 20 to 35% of total kilocalories -Less than 10% of kilocalories should be from saturated fat -Dietary cholesterol should be limited to 300 mg/day |
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Proteins |
-protein in food provides the amino acids necessary for buillding and maintaining body tissue -protein balance, both within the body and in the diet, is essential to life and health |
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Amino acids as basic building units |
-each protein is composed of hundreds of amino acids -amino acids form unique chain sequences to form specific proteins -when protein foods are eaten, proteins are broken down into amino acids -amino acids are reassembled in the body to form a variety of proteins |
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Proteins are relatively large, complex molecules |
May be subject to mutations or malformations -Dimensia -Alzheimers |
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Amino acids |
-named for chemical structure -basic structure of carbon, hydrogen, and oxygen -primary source of nitrogen in diet -some contain small amounts of valuable minerals |
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Indespensable amino acids |
Body cannot manufacture in sufficient quantity |
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Dispensable amino acids |
body can synthesize from indespensable |
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Conditionally indispensable amino acids |
normally synthesized but some health contains may require dietary intake |
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Protein balance |
Catabolism: breakdown Anabolism: resynthesis |
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Nitrogen balance (intake = excretion) |
-positive nitrogen balance: body stores more than it excretes -negative nitrogen balance: body takes in less than it excretes |
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Functions of proteins |
Primary tissue building Water and pH balance Metabolism and transportation Body defense system Energy system |
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Protein comprises bulk of |
Muscles Internal organs Brain Nerves Blood plasma |
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Digestive enzymes |
Amylases, lipases, proteases |
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Transport agents |
Lipoproteins, hemoglobin |
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Hormones |
Insulin and glucagon |
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Immune system uses protein |
To build -white blood cells -antibodies |
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Complete proteins |
Meat, fish, poultry, seafood Soy |
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Incomplete proteins |
Plant-origin foods: -grains -legumes -nuts -seeds -fruits and vegetables |
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Types of vegetarian diets |
Lacto-ovo vegetarian Lacto-vegetarian Ovo-vegerarian Vegan |
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Digestion of proteins |
Mouth Stomach: enzymatic breakdown of protein by proenzymes -hydrochloric acid -pepsin -rennin Small Intestine -Pancreatic secretions: trypsin, chymotrypsin, carboxypeptidase -Intestinal secretions: aminopeptidase, dipeptidase |
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RDAs (protein) |
-Relate to age, sex, weight -Highest at birth and slowly declines into adulthood -Men and women: 0.8 g/kg of desirable weight |
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DRIs (protein) |
10 to 35% of total caloric intake from protein (children and adults) |
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Basic Principles |
Principle of change -The body cannot use food as it is eaten -Food must be changed into simpler substances to be absorbed then used by cells to sustain life Principle of wholeness -The parts of the digestive process comprise a continuous whole -food components travel through the gastrointestinal (GI) system until they are delivered to cells or excreted |
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Mechanical digestion: gastrointestinal motility |
Muscles in GI wall produce: -Tonic contractions, which produce continuous movement -Periodic muscle contraction and relaxation, which mix food mass and move it forward |
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Chemical digestion: gastrointestinal secretions |
-Hydrochloric acid and buffer ions: produce the correct pH necessary for enzyme activity -Enzymes: specific digestive proteins for breaking down nutrients -Mucus: lubricates and protects the GI tract tissues and helps mix the food mass -Water and electrolytes: carry and circulate the products of digestion through the tract and into the tissues -Bile: divides fat into smaller pieces to assist fat enzymes |
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Mechanical digestion (mouth and esophagus) |
-Mastication breaks down food -Food is swallowed and passes down esophagus -Muscles at tongue base facilitate process -Gastroesophageal sphincter at stomach entrance relaxes, allowing food to enter, then constricts to retain food |
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Chemical digestion (mouth and esophagus) |
-Salivary glands secrete material containing salivary amylase or ptyalin -Ebners glads at the back of the tongue secrete a lingual lipase -Salivary glads also secrete a mucous material to lubricate and bind food particles, facilitating the swallowing of the food bolus -Secretions from the mucous glands in the esophagus help move food toward the stomach |
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Mechanical digestion (stomach) |
-Under sphincter control, the food enters upper portion of the stomach (fundus) -stomach muscles knead, store, mix, and propel food mass forward -by the time food mass reaches the lower portion of the stomach (antrum), it is semiliquid acid/food mix called chyme -pyloric valve slowly releases chyme into the first section of the small intestine (duodenum) |
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Chemical digestion (stomach) Three types of acid secretions |
-Hydrochloric acid: parietal cells in the stomach lining secrete acid to promote gastric enzyme activity -Mucus: secretions protect the stomach lining from the erosive effect of the acid and also bind and mix the food mass and help move it along -Enzymes: pepsinogen is secreted by stomach cells and is activated by acid to become pepsin, a protein splitting enzyme |
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Mechanical digestion (small intestine) |
-Perisaltic waves push food foward -Pendular movements stir chyme -Segmentation rings chop food mass into lumps -Longitudinal rotation rolls food in spiral motion, mixing it Surface villi motions stir and mix chyme |
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Chemical digestion (small intestine) Pancreatic enzymes |
-Carbohydrate: pancreatic amylase converts starch to maltose and sucrose -Protein: trypsin and chymotrypsin split large protein molecules into small peptide fragments and eventually into single amino acids from peptide chains -Fat: pancreatic lipase converts fat to glycerides and fatty acids |
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Chemical digestion (small intestine) intestinal enzymes |
-Carbohydrate: disaccharides convert disaccharides into monosaccharides. -Protein: Enterokinase activates trypsinogen from the pancreas to become trypsin; amino peptidase removes end emino acids from polypeptides; dipeptidase splits dipeptides into amino acids -Fat: intestinal lipase splits fat into glycerides and fatty acids |
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Chemical digestion (small intestine) |
-Mucus: protects mucosal lining -Bile: emulsifying agent, aids fat digestion and absorption -Hormones: secretin for alkaline environment, cholecystokinin triggers release of bile |
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Small intestine: three absorbing structures |
-Mucosal folds: surface of small intestine piles into many folds -Villi: small, fingerlike projections -Microvilli: cover each villus Make inner surface 600 times greater than outer surface of intestinal wall |
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Absorption processes |
Simple diffusion: particles move outward in all directions toward areas of lesser concentration -Facilitated diffusion: uses a protein channel for carrier assisted movement of larger particles -Active transport: carrier partner (example: sodium) moves particles across a membrane -Pinocytosis: larger materials are engulfed by a cell |
