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Ch 7 ppt Ch 7 ppt Presentation Transcript

  • CHAPTER 7 MineralsEleanor D. Schlenker Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc.
  • Comparison of Vitamins and MineralsVitamins Complex organic molecules that serve primarily as coenzymes or regulators of body metabolismMinerals Simple elements with important roles in both structure and function Excess of one vitamin or mineral cannot remedy an existing deficit of another Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 2
  • Roles of MineralsExamples of Structural Functions Calcium and phosphorus: give strength to the bones and body frame Iron: provides the core for the heme in hemoglobin Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 3
  • Roles of Minerals – Cont’dExamples of Metabolic Functions Ionized sodium and potassium: exercise control over body water Iodine: necessary constituent of the thyroid hormone that sets the rate of metabolism in the cells Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 4
  • Concept of Bioavailability Bioavailability: proportion of an ingested nutrient that is absorbed and can be used in carrying out body functions Bioavailability is an important issue with minerals Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 5
  • Concept of Bioavailability – Cont’d Depends on many factors relating to both the food source and the recipient:  Binding substances in plants  Gastric acidity  Chemical form of the mineral  Other foods in the same meal  Body need Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 6
  • ClassificationMajor Minerals Seven minerals present in the body in larger amounts  Calcium, phosphorus, magnesium, sodium, potassium, sulfur, and chloride Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 7
  • Classification – Cont’dTrace Elements Ten minerals found in the body in smaller amounts  Iron, iodine, zinc, copper, manganese, chromium, cobalt, selenium, molybdenum, fluoride All of these minerals have a defined role in the body and must be supplied in the diet Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 8
  • Major MineralsCalcium Present in the largest amount Calcium balance is applied at three levels: 1. Intake-absorption-excretion balance 2. Bone-blood balance 3. Calcium-phosphorus blood serum balance Calcium absorption ranges from 20% to 60% of intake but decreases with age Absorption takes place in the small intestine, primarily the duodenum Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 9
  • CalciumFactors Increasing Absorption Vitamin D hormone Body need Dietary protein and carbohydrates Acid environment Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 10
  • Calcium – Cont’dFactors Decreasing Absorption Vitamin D deficiency Fat malabsorption Fiber and other binding agents Alkaline environment Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 11
  • Calcium in the Bones Bones and teeth contain about 99% of total body calcium As much as 700 mg of calcium enter and leave the bones each day Immobility and osteoporosis cause losses Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 12
  • Calcium in the Blood Approximately 1% of total body calcium circulates in the blood and other body fluids Blood calcium exists in two forms:  Bound calcium  Free ionized calcium Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 13
  • Control of Calcium Balance Calcium-phosphorus balance  Serum calcium-phosphorus solubility products Three control agents work together to maintain calcium balance: 1. Parathyroid hormone (PTH) 2. Vitamin D hormone (calcitriol) 3. Calcitonin Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 14
  • Physiologic Functions of Calcium Bone formation Tooth formation General metabolic functions  Blood clotting  Nerve transmission  Muscle contraction and relaxation  Cell membrane permeability  Enzyme activation Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 15
  • Calcium: Clinical Applications Disruption of the physiologic and metabolic functions of calcium is associated with:  Tetany • Decrease in serum ionized calcium  Rickets and osteomalacia • Deficiency of vitamin D hormone  Resorptive hypercalciuria and renal calculi • Risk of renal stones increases with the rise in urinary calcium Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 16
  • Calcium and Health Bone disease  Osteoporosis  Drug regimens required to lower risk of fracture  Prevention: high calcium intakes in infancy through adolescence Metabolic disease  Weight gain/body fatness  Hypertension  Cancer Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 17
  • Dietary Reference Intakes for CalciumAdequate Intake (AI) Youth ages 9 through 18: 1300 mg/day Men and women ages 19 to 50: 1000 mg/day After age 50: 1200 mg/day Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 18
  • Food Sources of Calcium Milk, cheese, yogurt Green leafy vegetables, broccoli, legumes, nuts, and grains contribute calcium  Oxalates and phytates compromise bioavailability Calcium-fortified soy milk, calcium-fortified juices, and calcium-fortified cereals Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 19
  • Phosphorus Makes up about 1% of total body weight Absorption is regulated by the vitamin D hormone calcitriol and phosphate carrier proteins Kidneys are the main excretion route for phosphorus and regulate serum phosphorus levels Usually 85% to 95% of the plasma phosphate filtered by the renal glomeruli is reabsorbed in the renal tubules Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 20
  • Phosphorus – Cont’dBone-Blood-Cell Balance Approximately 80% to 90% of body phosphorus is found in the skeleton and teeth combined with calcium Normal range for serum phosphorus in adults is 3.0 to 4.5 mg/dL Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 21
  • Phosphorus – Cont’dBone-Blood-Cell Balance – cont’d Levels below 2.5 or above 5.0 mg/dL demand immediate medical attention In its active phosphate form, phosphorus participates in the structure and function of all living cells Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 22
  • Phosphorus – Cont’d Phosphorus balance is under the control of two hormones that also control calcium: 1. Vitamin D hormone 2. PTH Phosphorus helps build bones and teeth Phosphorus is present in every living cell, where it participates in overall metabolism Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 23
  • Phosphorus – Cont’d General Metabolic Activities  Absorption of glycerol and glucose  Transport of fatty acids  Energy metabolism  Buffer system Clinical applications  Recovery from diabetic acidosis  Growth  Hypophosphatemia  Hyperphosphatemia Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 24
  • Dietary Reference Intakes for Phosphorus 1250 mg/day for those ages 9 to 18 years 700 mg/day for all adults over age 18 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 25
  • Food Sources of Phosphorus Milk and milk products Lean meats Phosphorus-containing additives in processed foods Soft drinks Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 26
  • Sodium Major cation in the extracellular fluids One of the most plentiful minerals in the body Easily absorbed in the small intestine; usually no more than 2% remains to be excreted in the feces Major route of excretion is through the kidney under the control of aldosterone Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 27
  • Physiologic Functions of Sodium Water balance Acid-base balance Cell permeability Muscle action Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 28
  • Dietary Reference Intakes for Sodium Adequate Intake (AI) is 1500 mg of sodium (approximately 3800 mg of table salt) for youth and young adults 1300 mg sodium (approximately 3300 mg table salt) for those ages 51 to 70 years 1200 mg (approximately 3000 mg table salt) for those ages 71 and older Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 29
  • Dietary Reference Intakes for Sodium – Cont’d Tolerable Upper Intake Level for sodium is 2300 mg/day Sodium intakes above the recommended level can lead to elevated blood pressure in sodium-sensitive individuals Processed foods account for most high sodium intakes Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 30
  • Potassium Twice as plentiful in the body as sodium Inside cells, where it guards intracellular water Relatively small amount of potassium in extracellular fluid is important for muscle function Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 31
  • Potassium – Cont’d Dietary potassium is readily absorbed in the small intestine Circulates in the gastrointestinal secretions and is reabsorbed Principal route of excretion is the urine Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 32
  • Physiologic Functions of Potassium Water balance Muscle action Carbohydrate metabolism Protein synthesis Control of blood pressure Acid-base balance Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 33
  • Dietary Reference Intakes for Potassium AI is 4700 mg/day for all adults Lower intakes increase blood pressure and bone loss Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 34
  • Food Sources of Potassium Legumes, whole grains, fruits such as oranges and bananas, leafy green vegetables, broccoli, potatoes, meats, and milk Persons who eat many servings of fruits and vegetables have potassium intakes of about 8 to 11 g/day Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 35
  • Magnesium Activates enzymes for energy production and tissue building Role in normal muscle action Possible contributor to positive health effects of DASH diet Decreases risk of metabolic syndrome May contribute to health benefits of whole grains Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 36
  • Dietary Reference Intakes for Magnesium RDA is 400 mg for men and 310 mg for women ages 19 to 50 RDA increases to 420 mg in men and 320 mg in women over age 50 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 37
  • Food Sources of Magnesium Widespread in nature and unprocessed foods Whole grains are good sources Milk contains only a modest amount of magnesium but is a major contributor to diets in the United States Other sources include nuts, soybeans, cocoa, seafood, dried beans and peas, and green vegetables Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 38
  • Chloride Accounts for about 3% of total body mineral content Found in the extracellular fluid, where it helps control water balance and acid-base balance Fair amount of ionized chloride is found in the gastrointestinal secretions Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 39
  • Sulfur Found in all body cells as a constituent of cell protein Elemental sulfur forms sulfate compounds with sodium, potassium, and magnesium Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 40
  • Sulfur – Cont’d Sulfur is also a part of the following: 1. Sulfur-containing amino acids 2. Glycoproteins in cartilage, tendons, and bone matrix 3. Detoxification products formed by intestinal bacteria 4. Organic molecules 5. Keratin in hair and nails Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 41
  • Essential Trace Elements An essential element is one required to sustain life and whose absence brings death Have a required intake of less than 100 mg/day Two major functions 1. To catalyze chemical reactions 2. To serve as structural components of larger molecules Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 42
  • Essential Trace Elements – Cont’d Ten trace elements are essential in human nutrition based on defined function and need 1. Iron 6. Molybdenum 2. Zinc 7. Chromium 3. Iodine 8. Fluorine 4. Manganese 9. Selenium 5. Copper 10. Cobalt Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 43
  • Iron Body iron is distributed in the following four forms: 1. Transport iron 2. Hemoglobin/myoglobin 3. Storage iron 4. Cellular iron Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 44
  • Absorption of Iron Iron balance is controlled at the site of absorption in the small intestine because there is no system for iron excretion once it has entered the body Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 45
  • Absorption of Iron – Cont’d Unabsorbed iron is excreted in the feces There are two forms of dietary iron: 1. Heme iron (found only in meat, fish, and poultry) 2. Nonheme iron (found in both plant and animal tissue) Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 46
  • Absorption of Iron – Cont’d Nonheme iron is absorbed less efficiently than the smaller heme iron molecule Ferric iron (Fe3+) must be reduced to the more soluble ferrous form (Fe2+) before it can be absorbed Gastric acid is required to reduce iron to the ferrous form Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 47
  • Factors Favoring Iron Absorption Three factors favor absorption: 1. Body need 2. Ascorbic acid (vitamin C) or other acids 3. Animal tissues Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 48
  • Factors Hindering Iron Absorption Five factors hinder absorption: 1. Binding agents such as phytates and oxalates 2. Low gastric acid 3. Infection 4. Gastrointestinal disease 5. Large amounts of calcium Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 49
  • Physiologic Functions of Iron Oxygen transport Cellular oxidation Immune function Growth needs Brain and cognitive function Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 50
  • Iron Deficiency Anemia Occurs in both developed and developing countries and results in a hypochromic microcytic anemia Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 51
  • Iron Deficiency Anemia – Cont’d Causes of iron deficiency anemia  Low iron intake  Blood loss  Gastrectomy  Malabsorption  Chronic disease Iron deficiency anemia is a worldwide problem Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 52
  • Dietary Reference Intakes for Iron RDA is 18 mg/day for women ages 19 to 50 8 mg/day for women ages 51 and over 8 mg/day for men ages 19 and over 27 mg/day for pregnant women Iron needs fall to 9 mg/day during lactation because the menses are usually absent during this period Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 53
  • Dietary Reference Intakes for Iron – Cont’d Individuals eating only plant foods are at increased risk of iron deficiency because this iron is less well absorbed Vegetarian adolescent girls need 26 mg/day Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 54
  • Iron Overload Adult men and women beyond the childbearing years with lower iron requirements are vulnerable to iron overload with excessive intakes of highly fortified foods or high-potency supplements Hemochromatosis  Genetic disease  High iron absorption regardless of liver stores Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 55
  • Food Sources of Iron Found in highest amounts in meat, fish, poultry, eggs, dried peas and beans, and whole grain and fortified breads and cereals Fortified grain products such as breakfast bars contain from 1 mg to 24 mg of iron per serving Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 56
  • Iodine Component of the hormone thyroxine produced in the thyroid gland Thyroxine controls the rate of energy metabolism in cells Body contains only 15 to 20 mg of iodine Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 57
  • Iodine – Cont’d Absorbed in the small intestine in the form of iodides Iodides are then loosely bound to proteins and carried by the blood to the thyroid gland Absorbed iodide not needed by the thyroid gland is excreted in the urine Thyroid-stimulating hormone (TSH) directs uptake of iodine by thyroid cells in response to plasma thyroid hormone levels Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 58
  • Physiologic Function of IodineThyroid Hormone Synthesis Major function of iodine is the synthesis of the thyroid hormone thyroxine Thyroxine regulates cell oxidation and basal metabolic rate (BMR) Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 59
  • Physiologic Function of Iodine – Cont’dPlasma Thyroxine Free thyroxine is secreted into the bloodstream and bound to plasma protein for transport to the cells Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 60
  • Iodine Deficiency DisorderGoiter Visible as a great enlargement of the thyroid gland Found in persons living where water and soil, and in turn locally grown foods, contain little iodine When iodine is not available, the thyroid gland cannot produce a normal quantity of thyroxine Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 61
  • Iodine Deficiency Disorder – Cont’dCretinism Result of severe iodine deficiency during periods of critical brain development Irreversible mental retardation and disability Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 62
  • Dietary Reference Intakes for Iodine RDA is 150 µg/day for both men and women 220 µg/day during pregnancy 290 µg/day during lactation Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 63
  • Food Sources of Iodine Seafood is rich in iodine Foods vary depending on the iodine content of the soil and the iodine compounds used in processing Iodized table salt is fortified with 1 mg iodine per 10 g of salt Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 64
  • Zinc Participates in many metabolic activities as a component of over 100 different enzymes and a factor in growth Present in minute quantities in all body organs, tissues, fluids, and secretions Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 65
  • Zinc – Cont’d Closely involved with deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) metabolism and protein synthesis Necessary for tissue growth to progress at normal rates Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 66
  • Zinc Deficiency Clinical problems stem from zinc deficiency:  Hypogonadism  Loss in taste and smell  Impaired wound healing  Impaired growth and development  Impaired immune function  Malabsorption Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 67
  • Dietary Reference Intakes for Zinc RDA is 11 mg for men and 8 mg for women Needs are lower for women because of their generally smaller body mass Adolescent girls and older adults are most likely to have low intakes Vegetarians have a higher risk for deficiency  Phytates in plant foods interfere with absorption Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 68
  • Food Sources of Zinc Good sources of dietary zinc are seafood (especially oysters), meat, and eggs Less rich sources are legumes and whole grains Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 69
  • Copper Copper and iron have many characteristics in common:  Both are components of cell enzymes  Both are involved in energy production  Both participate in hemoglobin synthesis Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 70
  • Copper – Cont’d Copper occurs naturally in many foods, so dietary deficiency is rareDietary Reference Intake Current RDA for copper is 900 µg/day (0.9 mg/day) Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 71
  • Manganese The adult body contains about 20 mg of manganese distributed in the liver, bones, pancreas, and pituitary gland Part of important cell enzymes Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 72
  • Manganese – Cont’d Deficiency has been reported in patients with pancreatic insufficiency and protein-energy malnutritionDietary Reference Intake 2.3 mg/day for men and 1.8 mg/day for women Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 73
  • Chromium Precise amount of chromium in the body is not known Found in minute amounts in liver, soft tissues, and bone Part of a protein complex that potentiates insulin activity and helps move glucose into cells No evidence that chromium picolinate is effective as a body-building and weight-loss supplement Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 74
  • Dietary Reference Intakes for Chromium 35 µg/day for men and 25 µg/day for women ages 19 to 50 30 µg/day for men and 20 µg/day for women above age 50 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 75
  • Food Sources of Chromium Liver Cheddar cheese Wheat germ Whole grains Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 76
  • Cobalt Found in only minute traces in body tissues with storage in the liver Cobalt is provided in the human diet only in the form of vitamin B12 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 77
  • Selenium Deposited in all body tissues except fat Concentrations are highest in liver, kidney, heart, and spleen Integral part of an antioxidant enzyme that protects cells and lipid membranes from oxidative damage Selenium and vitamin E spare each other Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 78
  • Selenium – Cont’dDietary Reference Intakes RDA for all adults is 55 µg/dayFood Sources Seafood, legumes, whole grains, lean meats, and dairy products Vegetables contain only small amounts Amount depends on soil content Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 79
  • Molybdenum Enzyme cofactor in hydroxylation reactionsDietary Reference Intakes RDA is 45 µg/day for men and womenFood Sources Richest sources generally include legumes, whole grains, and nuts Animal products, fruit, and most vegetables are poor sources Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 80
  • Fluoride Accumulates in the calcified tissues and protects bones and teeth from mineral loss (resorption) If fluoride is present when calcium- phosphorus crystals are being formed, a fluoride ion (F-) replaces a hydroxyl ion (OH-) in the crystal Helps prevent dental caries and osteoporosis Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 81
  • Fluoride – Cont’dDietary Reference Intakes AI for men is 4 mg/day AI for women is 3 mg/dayFood Sources Fish, fish products, and tea contain the highest amounts 1 ppm added to most public water supplies Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 82
  • Water BalanceBody Water Distribution A woman’s body is about 50% to 55% water A man’s body is about 55% to 60% water Difference based on the fact that men have greater muscle mass (higher in water content) and women have more fat (lower in water content) Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 83
  • Functions of Water Provides form and structure Fluid environment for chemical reactions Fluid for transport of nutrients and waste Helps control body temperature Fluid for dissolving medications Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 84
  • Water Input Preformed water in beverages Preformed water in food Metabolic water produced by cell oxidation Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 85
  • Water Balance Water leaves the body through the kidneys, skin, and lungs and feces Intake and output must remain in balance to sustain normal hydration levels Conditions of abnormal water loss or inadequate access to water can lead to dehydration Loss of body fluids is especially dangerous in infants, whose bodies contain a higher proportion of fluids Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 86
  • Water Needs Clinical situations influence water needs:  Uncontrolled diabetes mellitus  Cystic fibrosis  High fiber intake  High protein intake  Intense athletic activity  Impaired thirst in older persons  Certain medications Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 87
  • Water Compartments Body water is divided into two major compartments: 1. The water outside the cells—the extracellular fluid compartment, which includes the blood plasma and interstitial fluid 2. The water inside the cells—the intracellular fluid compartment Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 88
  • Forces Controlling Water Distribution The amounts of solutes or particles in solution The membranes that separate water compartments Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 89
  • Influence of Electrolytes on Water Balance Concentration of electrolytes is measured in milliequivalents per liter (mEq/L) Ions carry electrical charges and are distributed to maintain electroneutrality Potassium controls the amount of water in the cells, and sodium controls the amount of water outside the cells Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 90
  • Influence of Plasma Protein on Water Balance Plasma proteins—albumin and globulin— control the movement of water in and out of the capillaries Capillary fluid shift mechanism allows water and nutrients to flow into the cell and cell waste to return to the capillary Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 91
  • Influence of Hormones on Water Balance Antidiuretic hormone Aldosterone Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 92