1323Chapter 8 minerals and water

Chapter 8
Minerals and Water

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Why Is Water So Important?
Water is the most abundant substance in body.
 Average healthy adult is about 60 percent water
 Muscle: 65 percent water, fat: 10 to 40 percent
water
 Age and body composition influence the % of
water in the body
 We can only survive a few days without water

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Your Body is Mostly Water

Figure 8.1
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Body Water Balance
 Water is balanced among fluid compartments
 Intracellular fluids: inside cells (60-75% of body

water)
 Extracellular fluids: interstitial fluid between
cells and fluid in the blood (25-40% of body water)
 Electrolytes: minerals that help maintain fluid
balance

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Water as Part of Body Fluids

Figure 8.2
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Functions of Body Water
 Acts as universal solvent and a transport medium
 Medium for many chemical reactions in body
 As part of blood, helps transport oxygen, nutrients,
hormones to cells
 As part of interstitial fluid (between cells), helps
transport waste products away from cells for
excretion
 Helps maintain body temperature
 Is a lubricant for joints, eyes, and is part of mucus and
saliva

 Is a protective cushion for brain, organs, fetus

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Water Helps Regulate Your Body
Temperature

Figure 8.3
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Maintaining Water Balance
 Water balance: water consumed = water lost
 We take in water through beverages and food
 We lose water through the kidneys (as urine), large
intestine, lungs, and skin (as sweat)
 Insensible water loss: through evaporation from
skin and when we exhale

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The Concept of Water Balance:

Intake Equals Output

Figure 8.4
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Water Content of Foods

Figure 8.7
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How Much Water Do You Need and
What Are the Best Sources?
 Daily water needs vary depending on physical activity,
environmental factors, and diet.
 Adequate Intake for water is based on reported total water
intake of healthy Americans
 Men: 16 cups/day (about 13 cups of beverages)
 Women: 12 cups/day (about 9 cups of beverages)
 Approximately 2 ½ to 3 ½ liters of fluid per day


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The Best Way to Meet Your Daily Water
Needs

Figure 8.8
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Think Before You Drink: Can Water
Boost Your Brain?

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Benefits of An Adequate Water Intake
 Decreased risk of
 Kidney stone formation
 Bladder cancer
 Colon cancer
 Breast cancer?

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Signs of Adequate Water Intake
 Mouth is moist
 Urine is a pale yellow color

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Urine Color Can Signal Dehydration

Figure 8.6
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Dehydration
 Can result from inadequate water intake or too much
water loss
 The thirst mechanism signals dehydration.
 Dry mouth due to increased electrolyte concentration
in blood: less water available to make saliva
 Blood volume decreases, sodium concentration
increases in blood
 Brain triggers thirst mechanism and secretion of
antidiuretic hormone (ADH) to reduce urine output
 Fluid inside cells moves into blood by osmosis

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Who Is Most at Risk for Dehydration?
 Anyone suffering from excessive vomiting and diarrhea,
or excessive perspiration
 Very young infants and children
 The elderly
 Active people in very warm climates

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Water Intoxication
 For healthy individuals it is difficult to consume too much
water
 Must drink a large amount of water in a short period of
time
 Athletes
 Hazing
 Contest
 Causes hyponatremia a condition of too little sodium in
the blood; organs swell causing fatigue, confusion,
disorientation, death

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Bottled Water
| Bottled Water

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What are minerals?
 Inorganic elements
 Needed in the diet in small amounts (milligrams and
micrograms
 Needed for life functions

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Factors Affecting Mineral Bioavailabilty
 Composition of the diet
 Lactose enhances calcium absorption
 Phytic acid, oxalic acid, tannins interfere with
absorption of iron, calcium, sometimes magnesium
and zinc
 Form the mineral comes in

 Heme versus non-heme iron
 Competition with other minerals
 Excess zinc can interfere with copper absorption
 Body’s need for the mineral
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Classification of Minerals
 Major minerals (macrominerals): needed in amounts
>100 µg/day
 Trace minerals (microminerals): needed in amounts
<20 µg/day
 Major minerals are needed in larger amounts
 Sodium, chloride, potassium, magnesium, sulfur play
key roles in fluid balance.
 Calcium, phosphorus, magnesium work together to
strengthen bones and teeth.

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Classification of Minerals
Trace minerals (microminerals) are needed in small
amounts: <20 µg/day
 Present even in smaller amounts in body
 Play several essential roles

 Chromium and iodine help certain hormones
 Iron maintains healthy red blood cells
 Fluoride protects teeth
 Several trace minerals act as cofactors

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The Minerals in Your Body

Figure 8.9
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