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Lecture Outline Chapter 9 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Water and Minerals Chapter 9 Insert photo from 1 st page of chapter
Chapter Learning Outcomes 1.Discuss the functions of water in the body as well as typical sources of intakes and losses. 2.Discuss how the body maintains its water balance. 3.List major signs and symptoms of heat-related illnesses. 4.Classify mineral nutrients as major, trace, or ultratrace minerals. 5.Describe factors that can affect the absorption, retention, and availability of mineral nutrients.
Chapter Learning Outcomes (continued) 6.List key functions and major food sources of mineral nutrients. 7.Identify signs and symptoms associated with deficiencies as well as excesses of mineral nutrients. 8.Describe roles of minerals in achieving and maintaining good health. 9.Identify major risk factors for hypertension and osteoporosis.
Quiz Yourself True or False Quiz Yourself True or False 1.Your body constantly loses water through insensible perspiration, a form of water loss that is not the same as sweat. T F 2.Ounce per ounce, cottage cheese contains more calcium than plain yogurt. T F 3.Potassium, sodium, and chloride ions are involved in fluid balance. T F 4.Arsenic is an ultratrace mineral. T F 5.In general, plants are good dietary sources of iron because the plant pigment chlorophyll contains iron. T F
Quiz Yourself True or False Quiz Yourself True or False 1.True Your body constantly loses water through insensible perspiration, a form of water loss that is not the same as sweat. 2.False Ounce per ounce, cottage cheese contains less calcium than plain yogurt. 3.True Potassium, sodium, and chloride ions are among the ions involved in fluid balance. 4.True Arsenic is an ultratrace mineral. 5.False In general, plants are not good dietary sources of iron. The plant pigment chlorophyll contains magnesium not iron.
Water Water (H 2 O) –Comprised of 2 hydrogen atoms and 1 oxygen atom –Needs no digestion and is easily absorbed –Makes up 45 to 75% of body weight Elderly ~45% Infants ~75% Elderly ~45% Infants ~75% –Major solvent –Very essential—without water, death occurs within 1 to 2 weeks.
Body Temperature Regulation Metabolism generates body heat –If body temperature reaches 106 0 F, excess heat denatures enzymes and damages body tissues which may result in death. –Evaporation of water in perspiration releases heat to maintain normal body temperature. Each liter of perspiration that evaporates represents loss of ~500 kcal of energy.
Body Water Compartments Intracellular water (fluid): water inside cells Extracellular water (fluid): water surrounding cells or in blood vessels (plasma) Plasma membrane of human cell is selectively permeable Osmosis — the diffusion (movement) of water through a selectively permeable membrane Concentration of substances dissolved in water influences osmosis
Body Water Distribution Simple diffusion – molecular movement from a region of higher to lower concentration Insert figure 9.1
Body Water Distribution Osmosis – movement of water through a selectively permeable membrane Insert Figure 9.2
Two Major Water Compartments Intracellular Water Water inside the cells ~ 2/3 of body water is intracellular Extracellular Water Water surrounding the cells or in the fluid portion of blood (plasma) Balance between intra- and extracellular fluid is maintained by concentration of ions. Main ions = sodium, potassium, chloride, and phosphate
Fluid Compartments in the Body Insert Figure 9.3Insert Figure 9.3
Maintaining Proper Hydration Hydration refers to adequate water status shifts in ion concentration can affect hydration. Insert figure 9.1
Sources of Water Total Water Intake –Includes water in beverages and foods Water weight of fruits and vegetables typically ranges from 60 to 95%.Water weight of fruits and vegetables typically ranges from 60 to 95%. Metabolic Water –Water formed by cells as a metabolic by- product
How Much Water is in That Food or Beverage? Insert Table 9.1Insert Table 9.1
The Essential Balancing Act Body water is lost through: –urine, perspiration, exhaled air, feces, and insensible perspiration. Insensible perspiration: body water that passes through the skin and is not from sweat glands. Typical fluid intake = fluid lost Average is ~2.5 qt/d
Kidneys and Hydration Kidneys: –Are the major regulator of body’s water content and ion concentration. –Maintain proper hydration by filtering excess ions from the blood. Remove excess sodium ions; water follows sodium.Remove excess sodium ions; water follows sodium. –Remove drugs and metabolic wastes. Urea and uric acid — waste products of protein metabolism.Urea and uric acid — waste products of protein metabolism.
Water Conservation Water conservation occurs when a person is hot and perspires heavily.Water conservation occurs when a person is hot and perspires heavily. Hormones that participate in sodium and waterHormones that participate in sodium and water conservation include: conservation include: -Antidiuretic hormone (ADH) -Aldosterone
Effects of Antidiuretic Hormone and Aldosterone on Kidneys Insert Table 9.7Insert Table 9.7
How Much Water Is Needed? Adequate Intake (AI) for total water (including water in foods) is: Young Women = 11 cups (2.7 L)/day Young Men = 15.5 cups (3.7 L)/day Urine output is best indicator of adequate water intake.
What Is a Diuretic? Diuretics — substances that increase urine output. Two common diuretics: Caffeine – In coffee, tea, “energy” drinks, and soft drinks Alcohol – In beer, wine, and spiritis Inhibits ADH resulting in urinary water losses > amount of fluid consumed “Hangovers” may be an effect of dehydration on the brain.
Dehydration When the body’s fluid loses are greater than its input, dehydration occurs. Weight loss is a sign of dehydration.Weight loss is a sign of dehydration. Every 16 oz of water lost by the body represents 1 lb of body weight.
Dehydration Body fluid lossSymptom/condition 1 to 2%Fatigue and thirst 4%Loss of muscular strength and endurance 7 to10%Severe weakness 20%Death
People at Risk for Dehydration Older adults – do not sense thirst as quickly as younger people.Older adults – do not sense thirst as quickly as younger people. Sick people – especially sick children with fever, vomiting, and diarrhea.Sick people – especially sick children with fever, vomiting, and diarrhea. Athletes and people who work or exercise outdoorshot weatherAthletes and people who work or exercise outdoors in hot weather.
Can Too Much Water Be Toxic? Water intoxication – too much water consumed at a time or conditions in which kidneys have difficulty filtering water from blood Excess water dilutes sodium concentration of blood, disrupting water balanceExcess water dilutes sodium concentration of blood, disrupting water balance –Signs and symptoms: Dizziness, headache, confusion, poor coordination, bizarre behavior, and seizuresDizziness, headache, confusion, poor coordination, bizarre behavior, and seizures
Minerals: Basic Concepts What are minerals? Elements in Earth’s rocks, soil, and natural water sources.Elements in Earth’s rocks, soil, and natural water sources. About 15 mineral elements are essential nutrients.About 15 mineral elements are essential nutrients. Classified as micronutrients because they are required in mg or mcg amounts.Classified as micronutrients because they are required in mg or mcg amounts.
Classifying Mineral Nutrients Main categories of mineralsMain categories of minerals –Major Required in amounts >100 mg/dRequired in amounts >100 mg/d –Trace Required in amounts <100 mg/dRequired in amounts <100 mg/d –Ultratrace Body contains very small amountsBody contains very small amounts
Minerals with Known or Possible Roles in the Body Insert Table 9.2
Why Are Minerals Necessary? Diverse roles, including: Diverse roles, including: –Structural components of tissues –Ions –Blood clotting –Fluid balance –Acid-base balance –Cofactors in chemical reactions –Part of certain enzymes and hormones –Aid in energy release from macronutrients
Sources of Minerals Most foods contain minerals –Animal foods generally contain higher amounts of minerals than plant foods. –Processing often reduces mineral contents of foods. Bioavailability of minerals varies –In general, minerals in animal foods are more easily absorbed than minerals in plant foods.
Other Sources of Minerals Tap water “Hard” water contains a variety of minerals, including calcium, sulfur, copper, iron, and zinc.“Hard” water contains a variety of minerals, including calcium, sulfur, copper, iron, and zinc. Most public water supplies provide optimal fluoride levels, because the mineral has been added to the water.Most public water supplies provide optimal fluoride levels, because the mineral has been added to the water. Dietary supplements –A daily multiple vitamin and mineral supplement is generally safe for healthy people. –Supplements of single minerals may be toxic, if taken in excess.
Mineral Intakes Many minerals have Many minerals have a narrow range of safe intake. As a result, it is relatively easy to consume a toxic amount, especially by taking supplements that only contain a particular mineral. Inser t Figur e 9.9
Major Minerals: Calcium The most plentiful mineral in human bodyThe most plentiful mineral in human body –> 99% is in bones and teeth –~ 1% is in extracellular fluid Healthy adults absorb ~25% of calcium.Healthy adults absorb ~25% of calcium. –Absorption increases during growth. –Absorption decreases with advanced age, vitamin D deficiency, diarrhea, and high intakes of phosphorus, oxalic acid, and phytic acid.
Why Is Calcium Necessary? Functions of calcium include: Bone formation and maintenanceBone formation and maintenance Structural component of teethStructural component of teeth Muscle contractionMuscle contraction Blood clot formationBlood clot formation Nerve impulse transmissionNerve impulse transmission Cell metabolismCell metabolism May help control blood pressure and immune functioning
Bone Development and Maintenance Bones are constantly remodeled in response to physical stress. Remodeling involves two types of cells:Remodeling involves two types of cells: Osteoclasts — tear down bone tissue where it is not needed Osteoblasts — add bone to where it is needed
Thyroid and Parathyroid Glands Insert Figure 9.11
Thyroid gland: Secretes calcitonin when blood calcium is too high Stimulates osteoblastsStimulates osteoblasts Parathyroid glands: Secrete parathyroid hormone (PTH) when blood calcium is too low Stimulates osteoclastsStimulates osteoclasts Role of Thyroid and Parathyroid Glands
Calcium Content of Selected Foods Insert Table 9.4
Good Food Sources of Calcium Insert figure 9.13
What is Osteoporosis? A chronic disease characterized by low bone mass and reduced bone structure leading to increased risk of bone fracturesA chronic disease characterized by low bone mass and reduced bone structure leading to increased risk of bone fractures –Among people over age 50, ~10 million have osteoporosis and 34 million are at risk. – An estimated 1.5 million Americans have an osteoporosis-related fracture each year. Insert figure 9.14
Calcium Toxicity Upper Level (UL) is 2500 mg/d – Excess calcium can result in hypercalcemia –Signs/symptoms: »Kidney stones, bone pain, muscle weakness, fatigue, and hypertension
Sodium (Na) Table salt = sodium + chlorideTable salt = sodium + chloride –1 tsp salt supplies 2325 mg sodium Why is Sodium Necessary?Why is Sodium Necessary? –Major positively charged ion in extracellular fluid –Conducts nerve impulses –Involved in transporting glucose and amino acids into cells
Sodium Content of Selected Foods/Food Additive Insert Table 9.7
Dietary Adequacy for Sodium Only ~ 180 mg sodium required per dayOnly ~ 180 mg sodium required per day –AI = 1500 mg/d Those who perspire heavily lose sodium in sweat and need moreThose who perspire heavily lose sodium in sweat and need more
Sodium Deficiency and Toxicity DeficiencyDeficiency –May occur when > 2 to 3% of body weight is lost through sweating ToxicityToxicity –UL = 2300 mg/d Average American consumes >2500 mg/dAverage American consumes >2500 mg/d –High sodium intakes associated with increased risk of hypertension
Sodium and Hypertension Hypertension — condition characterized by persistently elevated blood pressureHypertension — condition characterized by persistently elevated blood pressure –Estimated 27% of American adults have the condition –Hypertension increases risk of: Heart diseaseHeart disease StrokeStroke Kidney failureKidney failure
Blood Pressure Systolic pressure — maximum blood pressure within arteries when ventricles of the heart contractSystolic pressure — maximum blood pressure within arteries when ventricles of the heart contract Diastolic pressure — pressure when ventricles relax between contractionsDiastolic pressure — pressure when ventricles relax between contractions Systolic value is always higher than diastolic value Systolic value is always higher than diastolic value
Categories of Blood Pressure Levels in Adults Insert table 9.18
Insert Table 9.9 Many risk factors for hypertension can be controlled by following a healthy lifestyle.
Insert Table 9.10 Practical Steps to Reduce Risk of Hypertension
Potassium (K) Why is Potassium Necessary? Major positively charged ion in intracellular fluidMajor positively charged ion in intracellular fluid –Needed for nerve impulses, contracting muscles, and kidney function –Potassium-rich diets may reduce blood pressure Dietary Adequacy –AI = 4700 mg/d Most Americans consume ~2700 mg/dMost Americans consume ~2700 mg/d
Good Food Sources of Potassium Insert Figure 9.15
Potassium Content of Selected Foods Insert Table 9.11
Magnesium (Mg) Participates in >300 chemical reactionsParticipates in >300 chemical reactions Roles the body include:Roles the body include: –Regulation of muscle and nerve function –Maintenance of strong bones –Strengthening the immune system Dietary AdequacyDietary Adequacy –Adult RDA = 310 to 420 mg/d
Magnesium Content of Selected Foods Insert Table 9.12
Good Food Sources of Magnesium Insert Figure 9.16
Magnesium Deficiency and Toxicity DeficiencyDeficiency Rare among healthy AmericansRare among healthy Americans Most likely in girls between 14-18 yrs of ageMost likely in girls between 14-18 yrs of age ToxicityToxicity Results from ingesting excessive laxatives, antacids, or dietary supplementsResults from ingesting excessive laxatives, antacids, or dietary supplements
Iron (Fe) Why is Iron Necessary? Iron is a component of hemoglobin and myoglobin.Iron is a component of hemoglobin and myoglobin. Hemoglobin — iron containing protein in RBC that transports oxygen to tissues and some CO 2 away from tissuesHemoglobin — iron containing protein in RBC that transports oxygen to tissues and some CO 2 away from tissues Myoglobin — iron-containing protein in muscle cells that controls oxygen uptake from RBCMyoglobin — iron-containing protein in muscle cells that controls oxygen uptake from RBC Iron is involved in energy generation and immune function.Iron is involved in energy generation and immune function.
Iron Content of Selected Foods Insert Table 9.14
Iron: Dietary Adequacy RDARDA Women = 18 mg/dWomen = 18 mg/d Most females from ages 14 to 50 yrs have low intakes.Most females from ages 14 to 50 yrs have low intakes. Men = 8 mg/dMen = 8 mg/d Most males >age 9 yrs have adequate intakes.Most males >age 9 yrs have adequate intakes.
Iron Deficiency-Related Disorders Anemia impairs oxygen transport in blood. Insert figure 9.18 Normal RBC Hypochromic, microcytic RBC
Signs and Symptoms of Iron Deficiency Anemia Insert Table 9.15
Iron Toxicity Upper Limit (UL) = 45 mg/dUpper Limit (UL) = 45 mg/d May occur in children <6 yrs due to supplement overdoseMay occur in children <6 yrs due to supplement overdose Signs include vomiting and diarrhea, progressing to coma and deathSigns include vomiting and diarrhea, progressing to coma and death Hereditary HemochromatosisHereditary Hemochromatosis Common hereditary disorder resulting in excess iron absorptionCommon hereditary disorder resulting in excess iron absorption
Zinc (Zn) Why is Zinc Necessary? It’s a component of hundreds of enzymes and other proteins.It’s a component of hundreds of enzymes and other proteins. It is needed for:It is needed for: Wound healingWound healing Normal of taste and smellNormal of taste and smell DNA synthesisDNA synthesis Immune functionImmune function
Zinc Deficiency –Zinc deficiency often occurs in people with chronic digestive tract problems and exclusively breastfed infants. –Associated with delayed sexual maturation and growth retardation
Zinc Content of Selected Foods Insert Table 9.16
Zinc: Dietary Adequacy and Toxicity AdequacyAdequacy Adult RDA ranges from 8 to 13 mg/dAdult RDA ranges from 8 to 13 mg/d Children between 6 to 11 yrs at risk of deficiencyChildren between 6 to 11 yrs at risk of deficiency ToxicityToxicity Upper Limit (UL) = 40 mg/dUpper Limit (UL) = 40 mg/d May reduce HDL cholesterol levelMay reduce HDL cholesterol level >100 mg/d results in diarrhea, cramps, vomiting, and depressed immune system>100 mg/d results in diarrhea, cramps, vomiting, and depressed immune system
Iodide (I) Why is Iodide Necessary? Required for normal thyroid function and production of the thyroid hormone.Required for normal thyroid function and production of the thyroid hormone. The hormone controls the rateThe hormone controls the rate of metabolism. of metabolism. Iodide is added to regular table salt to prevent deficiency.Iodide is added to regular table salt to prevent deficiency.
Iodide Content of Selected Foods Insert Table 9.17
Iodide: Dietary Adequacy and Toxicity AdequacyAdequacy Adult RDA = 150 mcg/dAdult RDA = 150 mcg/d ToxicityToxicity UL = 1.1 mg/dUL = 1.1 mg/d May result in enlargement of thyroid glandMay result in enlargement of thyroid gland
Dietary Deficiency of Iodide Goiter Characterized by enlarged thyroid glandCharacterized by enlarged thyroid gland Common before advent of iodized salt in areas where iodine content of soil was poorCommon before advent of iodized salt in areas where iodine content of soil was poorCretinism Condition affecting infants born to women who were iodide deficient during pregnancyCondition affecting infants born to women who were iodide deficient during pregnancy
Selenium (Se) Why is Selenium Necessary? Part of a group of proteins called selenoproteinsPart of a group of proteins called selenoproteins Many selenoproteins are antioxidants.Many selenoproteins are antioxidants. May reduce risk of certain cancersMay reduce risk of certain cancers
Selenium Content of Selected Foods Insert Table 9.18
Dietary Adequacy, Deficiency, and Toxicity of Selenium AdequacyAdequacy Adult RDA = 200 mcg/dAdult RDA = 200 mcg/d Most Americans meet the RDAMost Americans meet the RDA DeficiencyDeficiency May occur with severe digestive tract conditionsMay occur with severe digestive tract conditions ToxicityToxicity Upper Limit (UL) = 400 mcg/dUpper Limit (UL) = 400 mcg/d Known as selenosisKnown as selenosis
Chromium (Cr) Why is Chromium Necessary? May enhance insulin’s action on cell membranesMay enhance insulin’s action on cell membranes “Holds the door open” for glucose entry into cells“Holds the door open” for glucose entry into cells Sources of Chromium Widely distributed in foodsWidely distributed in foods Dietary Adequacy — most diets are adequate Deficiency — causes impaired glucose tolerance Toxicity — not known
Chromium Content of Selected Foods Insert Table 9.16
Summary of Ultratrace Minerals Insert Table 9.19
Chapter 9 Highlight Bottled Water versus Tap Water According to results of surveys, Americans drink bottled water: Taste preferences Convenience Drinking bottled water is expensive and unnecessary, unless public water supply is disrupted.
What is Bottled Water? FDA Definition: Water intended for human consumption that is sealed in containers and has no added ingredients other than a substance that prevents growth of microbes, such as bacteria.
Is Bottled Water Safe to Drink? FDA regulates: –Levels of contaminants in water such as microbes, chemicals, and minerals –Requires water be sampled, analyzed, and found to be safe and clean before bottling
Is Tap Water Safe to Drink? The Safe Drinking Water Act requires water to undergo a thorough purification process and be tested for safety constantly.The Safe Drinking Water Act requires water to undergo a thorough purification process and be tested for safety constantly. If testing indicates water may pose a threat to public health, consumers are warned through media, and a “boil order” may be issued.If testing indicates water may pose a threat to public health, consumers are warned through media, and a “boil order” may be issued. “Boil order” = boiling water for 10 minutes to kill harmful microorganisms“Boil order” = boiling water for 10 minutes to kill harmful microorganisms
FDA Definitions for Classifying Some Types of Water Insert Table 9.A