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Chapter 12
Water and Major Minerals
Chapter Outline
I. Water: The Essential Ingredient for Life (Figure 12.1). *Water is the most essential
nutrient; we can live much longer without food than without water. Recommended water
intake is 1.0 milliliter to 1.5 milliliters per kilocalorie expended.
A. Functions of water (Figure 12.3). *Water is important for the movement of
nutrients and waste, cellular reactions, temperature regulation, and acid-base
balance. Moreover, fluids in the body lubricate and cushion joints, cleanse the eyes,
and moisten the food we eat.
1. Heat capacity
2. Cooling ability
3. Participation in metabolism
4. pH balance
5. Body fluids
B. Electrolytes and water: a delicate equilibrium (Figures 12.4 and 12.5). *Dissolved
ions, or electrolytes, help to maintain normal fluid balance.
Key terms: electrolyte, hydrogen bond, heat capacity, salts, ion, cation, anion, plasma,
sodium-potassium pump, semipermeable membrane, solute, osmosis, osmotic pressure
II. Intake Recommendations: How Much Water Is Enough?
A. Water excretion: Where does the water go? (Figure 12.9)
B. Water balance. *Fluid is lost from the body via the urine, skin, feces, and lungs.
The hormones ADH and aldosterone regulate fluid excretion from the kidneys.
1. Regulation of fluid excretion (Figure 12.10)
2. Regulation of blood volume and pressure (Figure 12.11)
3. Thirst. *The thirst response stimulates fluid intake. Caffeine, alcohol, and
diuretic medications increase fluid excretion. Dehydration results when fluid
intake is less than losses; it can seriously impair physical and mental
performance.
4. Water reabsorption in the gastrointestinal tract
C. Alcohol, caffeine, and common medications affect fluid balance
D. Dehydration (Figure 12.13)
E. Water intoxication
Key terms: insensible water loss, osmoreceptors, antidiuretic hormone (ADH),
vasoconstrictor, vasopressin, osmolarity, renin, angiotensin I, angiotensinogen, angiotensin
II, aldosterone
III. Major Minerals. *Minerals are inorganic elements and are categorized as major or
trace depending on the amount in the body and the amount needed in the diet.
A. Minerals in food
B. Bioavailability (Figure 12.15). *The bioavailability of minerals may be affected
by excess intake of single mineral supplements, phytate, oxalate, and fiber in plant
foods, and mineral status in the body.
Key terms: major minerals, trace minerals, phytate, oxalate
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IV. Sodium. *Sodium, the major extracellular cation, helps regulate water distribution and
blood pressure. Sodium needs (500 mg/day) are well below average intakes (3,000 mg to
6,000 mg/day).
A. Functions of sodium
B. Dietary recommendations for sodium
C. Sources of sodium
D. Hyponatremia
E. Hypernatremia
Key terms: hyponatremia, hypernatremia, hypervolemia
V. Potassium. *Potassium the major cation in the intracellular fluid, is necessary for nerve
and muscle function. It is provided in the diet mainly from unprocessed foods, including
fruits and vegetables.
A. Functions of potassium
B. Dietary recommendations for potassium
C. Sources of potassium (Figure 12.19)
D. Hypokalemia
E. Hyperkalemia
Key terms: hypokalemia, hyperkalemia
VI. Chloride. *Chloride is the major extracellular anion, and a component of stomach acid.
Chloride deficiency is most often associated with prolonged vomiting.
A. Functions of chloride
B. Dietary recommendations for chloride
C. Sources of chloride
D. Hypochloremia
Key terms: chloride shift, metabolic alkalosis
VII. Calcium. *Calcium, the most abundant mineral in the body, is stored in bones. It also
functions in blood clotting, nerve and muscle function, and cellular metabolism. Major
dietary sources of calcium are dairy products, calcium-fortified foods, and certain
vegetables.
A. Functions of calcium (Figure 12.20)
1. Bone structure
2. Nerve function
3. Blood clotting
4. Muscle contraction
5. Cellular metabolism
B. Regulation of blood calcium (Figure 12.21)
1. Vitamin D
2. Parathyroid hormone
3. Calcitonin
C. Dietary recommendations for calcium
D. Sources of calcium (Figure 12.22)
E. Calcium absorption
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F. Hypocalcemia
G. Hypercalcemia
H. Osteoporosis
Key terms: osteoblasts, osteoclasts, hydroxypatite, linear growth, fibrin, calmodulin, ciliary
action, hypocalcemia, hypercalcemia
VIII. Phosphorus. *Phosphorus is a key component of ATP, DNA, RNA, phospholipids, and
lipoproteins. Because phosphorus is widespread in foods, dietary phosphorus intake is
rarely inadequate.
A. Functions of phosphorus
B. Dietary recommendations for phosphorus
C. Sources of phosphorus (Figure 12.23)
D. Hypophosphatemia
E. Hyperphosphatemia
Key terms: phosphorylation, hypophosphatemia, hyperparathyroidism, hyperphosphatemia
IX. Magnesium. *Plant foods, like whole grains and vegetables, are important sources of
magnesium, which is a cofactor for hundreds of enzymes. Low levels of magnesium are
associated with kidney disease, alcoholism, and use of diuretics.
A. Functions of magnesium
B. Dietary recommendations for magnesium
C. Sources of magnesium
D. Hypomagnesemia
E. Hypermagnesemia
Key terms: hypomagnesemia, hypermagnesemia
X. Sulfur. *Sulfur does not function alone as a nutrient, but as a component of certain
amino acids, and the vitamins biotin and thiamin.
Classroom Activities
ACTIVITY 1: WHAT IS WRONG WITH THIS STATEMENT?
This is a critical thinking activity that can be completed as a homework assignment or as inclass group work. Students may need to use their books to assist them in finding the
answers.
Directions: Determine which words are inaccurate within each statement. Change the words
so the statement is true.
1. The body maintains its electrolyte balances through the intake and excretion of water and
the movement of proteins.
ANSWER: The body maintains its electrolyte balances through the intake and excretion of
water and the movement of IONS.
2. The human body is made up of approximately 25 to 45 percent water.
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ANSWER: The human body is made up of approximately 50 to 75 percent water.
3. Leaner people have proportionately less water than overweight people do because muscle
tissue is only about 10 percent water.
ANSWER: Leaner people have proportionately MORE water than overweight people do
because muscle tissue is heavier than fat.
4. The heat capacity of a substance is the amount of energy required to raise its temperature
3 degrees Celsius.
ANSWER: The heat capacity of a substance is the amount of energy required to raise its
temperature 1 degree Celsius.
5. When salts, such as sodium, dissolve in water they come apart and form free ions, which
are only positively charged.
ANSWER: When salts, such as sodium, dissolve in water they come apart and form free
ions, which are POSITIVELY AND NEGATIVELY charged.
6. Humans can survive longer without water than food.
ANSWER: Human can survive longer without FOOD than WATER.
7. Lettuce and cereal contain more water activity than chicken.
ANSWER: Lettuce and CHICKEN contain more water activity than CEREAL.
8. Depending on the amount of water, protein, and sodium consumed, the body loses about
a half liter of water each day through urine.
ANSWER: Depending on the amount of water, protein, and sodium consumed, the body
loses about ONE TO TWO LITERS of water each day through urine.
9. If an individual does not consume enough protein, the kidneys have to work harder to
eliminate excess urea from the body.
ANSWER: If an individual OVERCONSUMES protein, the kidneys have to work harder to
eliminate excess urea from the body.
10. Thirst is always a reliable guide to avoiding dehydration.
ANSWER: Thirst is NOT always a reliable guide to avoiding dehydration.
ACTIVITY 2: WHAT’S ALL THE HYPE ABOUT BOTTLED WATER?
The following activity can be used to illustrate the point that bottled and tap water can both
be acceptable and safe sources of drinking water. This activity can be used within the lesson
or for a group activity. As the class reviews the answers, the instructor can elaborate on
each statement.
Directions: For the first five questions identify whether the statement is describing bottled
water, tap water, or both. For the last five questions, determine if the statement is true or
false.
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1. Many times, this source of water is fluoridated.
2. The Environmental Protection Agency (EPA) enforces the standards for this water.
3. This type of water is often filtrated in homes, removing fluoride and chlorine.
4. The Food and Drug Administration (FDA) regulates this water.
5. This is the water that has Standards of Identity that set maximum allowable standards for
contaminants.
6. This water often contains minerals that interfere with the action of soap causing scum
build up and discoloration.
7. Individual states may have their own quality standards for the local distribution of this
kind of water.
8. Current Good Manufacturing Practices (CGMP) addresses issues with this type of water.
9. Overall, this water is considered safe drinking water.
10. This water has standard definitions in labeling.
True or False
11. _____Twenty-five percent of bottled water comes from a municipal water source.
12. _____One of the reasons bottled water has become so popular is because baby boomers
are seeking natural, low-calorie beverages.
13. _____All municipal water must be fluoridated.
14. _____Water softeners exchange minerals in tap water, such as calcium and magnesium,
for sodium.
15. _____Standards that regulate bottled water are no more rigid than those that regulate tap
water.
ANSWERS
1. tap
2. tap
3. tap
4. bottled
5. bottled
6. tap
7. bottled
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8. bottled
9. both
10. bottled
11. true
12. true
13. false
14. true
15. true
ACTIVITY 3: FUNCTIONS OF MINERALS
The following can be used as a pre-quiz to the lesson on minerals. It can also be used as a
homework assignment.
Directions: Match the mineral with its appropriate function in the body. Answers can be
used more than once.
a. sodium
b. potassium
c. chloride
d. calcium
e. sulfur
f. magnesium
g. phosphorus
1. ____ This mineral does not function alone as a nutrient, but as a component of certain
amino acids, and the vitamins biotin and thiamin.
2. ____ Low levels of this mineral are associated with kidney disease, alcoholism, and
diuretics.
3. ____ The key component of ATP, DNA, RNA, phospholipids, and lipoproteins.
4. ____ The most abundant mineral in the body.
5. ____ Adequate dietary intake of this mineral and vitamin D, along with physical activity,
can help reduce the risk for osteoporosis.
6. ____ A major extracellular cation that helps regulate water distribution and blood
pressure.
7. ____ A major extracellular anion and component of stomach acid.
8. ____ A major cation in the extracellular fluid that is necessary for nerve and muscle
function.
9. _____ Hyponatremia is a result of a low concentration of this mineral.
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10. ____ Hyperkalemia can cause cardiac arrest and death. This condition results from low
concentrations of this mineral.
ANSWERS
1. e. sulfur
2. f. magnesium
3. g. phosphorus
4. d. calcium
5. d. calcium
6. a. sodium
7. c. chloride
8. b. potassium
9. a. sodium
10. b. potassium
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