Chapter 8 - Chapter Summary for Nutrition Concepts and Controversies 11e Chapter 8 Water and Minerals Water provides the medium for transportation

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Chapter Summary for  Nutrition: Concepts and Controversies  11e Chapter 8 – Water and Minerals Water provides the medium for transportation, acts as a solvent, participates in chemical reactions, provides lubrication and shock protection, and aids in temperature regulation in the human body. Water losses from the body necessitate intake equal to output to maintain balance. The brain regulates water intake; the brain and kidneys regulate water excretion. Dehydration and water intoxication can have serious consequences. Many factors influence a person’s need for water. The water of beverages and foods meets nearly all of the need for water, and a little more is supplied by the water formed during cellular breakdown of energy nutrients. Hard water is high in calcium and magnesium. Soft water is high in sodium, and it dissolves cadmium and lead from pipes. Public drinking water is tested and treated for safety. All drinking water originates from surface water or groundwater that are vulnerable to contamination from human activities. Mineral salts form electrolytes that help keep fluids in their proper compartments and buffer these fluids, permitting all life processes to take place. Calcium makes up bone and tooth structure and plays roles in nerve transmission, muscle contraction, and blood clotting. Calcium absorption rises when there is a dietary deficiency or an increased need such as during growth. Most of the phosphorus in the body is in the bones and teeth. Phosphorus helps maintain acid-base balance, is part of the genetic material in cells, assists in energy metabolism, and forms part of cell membranes. Under normal circumstances, deficiencies of phosphorus are unknown. Most of the body’s magnesium is in the bones and can be drawn out for all the cells to use in building protein and using energy. Most people in the United States choose diets that lack sufficient magnesium. Sodium is the main positively charged ion outside the body’s cells. Sodium attracts water. Thus, too much sodium (or salt) raises blood pressure and aggravates hypertension. Diets rarely lack sodium. Potassium, the major positive ion inside cells, is important in many metabolic functions. Fresh, whole foods are the best sources of potassium. Diuretics can deplete the body’s potassium and so can be dangerous; potassium excess can also be dangerous. Chloride is the body’s major negative ion; it is responsible for stomach acidity and assists in maintaining proper body chemistry. No known diet lacks chloride. Sulfate is a necessary nutrient used to synthesize sulfur-containing body compounds. Iodine is part of the hormone thyroxine, which influences energy metabolism. The deficiency diseases are goiter and cretinism. Iodine occurs naturally in seafood and in foods grown on land that was once covered by oceans; it is an additive in milk and bakery products. Large amounts are poisonous. Potassium iodide, appropriately administered, blocks some radiation damage to the thyroid during radiation emergencies. Most iron in the body is
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This note was uploaded on 07/01/2011 for the course NTR 101 taught by Professor Hendry during the Spring '10 term at Holyoke CC.

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Chapter 8 - Chapter Summary for Nutrition Concepts and Controversies 11e Chapter 8 Water and Minerals Water provides the medium for transportation

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