Download Chapter 10: Water and Minerals: The Ocean Within

Chapter
12
Water and
Major Minerals
Water: The Essential
Ingredients for Life
• Water makes up
45–75 percent of
a person’s weight.
Photo: © Piotr Marcinski/ShutterStock, Inc.
Functions of Water
Electrolytes and Water:
A Delicate Equilibrium
• Cation
(positively
charged ions)
• Anions
(negatively
charged ions)
Water in the Body
• Major fluid compartments
• Intracellular fluid
• Extracellular fluid
• Interstitial fluid
• Plasma
Water in the Body
• Sodiumpotassium pump
• Semipermeable
membrane
• Osmosis
Intake Recommendations: How
Much Water Is Enough?
• Adequate intake includes drinking
water, beverages, and food
• Recommendations are higher for
• Pregnancy
• Lactation
• Athletes and active people
• Sports drinks and water absorption
Intake Recommendations: How
Much Water Is Enough?
• Water Excretion: Where
Does the Water Go?
• Insensible water losses
© Photodisc
Intake Recommendations: How
Much Water Is Enough?
• Water Balance
•
•
•
•
Regulation of fluid excretion
Regulation of blood volume and pressure
Thirst
Water reabsorption in the GI tract
Intake Recommendations: How
Much Water Is Enough?
• Alcohol, caffeine, and
common medications
affect fluid balance
• Dehydration
• Water intoxication
Intake Recommendations: How
Much Water Is Enough?
• Water Balance
• Regulation of Blood Volume and Pressure
• Renin, angiotensin I, angiotensinogen,
angiotensin II, adlosterone
• Thirst
• Water reabsorption in the GI tract
Intake Recommendations: How
Much Water Is Enough?
• Alcohol, caffeine,
and common
medications affect
fluid balance
Major Minerals
• Minerals in
foods
• Bioavailabiltiy
Sodium
• Functions
• Fluid balance
• Nerve impulse transmission
• Dietary recommendations
• Food sources and recommended intake
• Salt
• Processed and convenience foods
• Limit to 2,300 milligrams/day (DV)
• Hyponatremia
• Hypernatremia
• Hypertension
Potassium
• Functions
• Muscle contraction
• Nerve impulse transmission
• Fluid balance
• Dietary recommendations
• Food sources
• Unprocessed foods: fruits,
vegetables, grains
• Hypokalemia
• Hyperkalemia
© Photodisc
Chloride
• Functions of chloride
• Fluid balance
• Hydrochloric acid (stomach acid)
• Dietary recommendations
• Food sources of chloride
• Table salt
• Hypochloremia
Calcium
• Functions
•
•
•
•
•
Bone structure
Nerve function
Blood clotting
Muscle contraction
Cellular metabolism
Regulation of Blood Calcium
• Hormones
• Vitamin D
• Parathyroid hormone
• Calcitonin
• Target tissues
• Small intestine
• Kidneys
• Bone
Calcium
• Dietary recommendations for calcium
• Food sources
• Milk and dairy products
• Green vegetables, tofu, fortified foods
•
•
•
•
Calcium absorption
Hypocalcemia
Hypercalcemia
Osteoporosis
Phosphorus
• Functions
• Bone structure
• Component of ATP, DNA,
RNA, phospholipids
• Dietary recommendations
• Food sources
• Meat, milk, eggs
• Processed foods
• Hypophosphatemia
• Hyperphosphatemia
Magnesium
• Functions
• DNA and protein synthesis
• Blood clotting, muscle
contraction, ATP production
• Dietary recommendations
• Food sources
• Whole grains, vegetables,
legumes, tofu, seafood
• Hypomagnesemia
• Hypermagnesemia
© Photodisc
Sulfur
• Not used only as a nutrient
• A component of organic compounds
• Important in protein sturcture
Major Minerals and Health
• Hypertension
• High blood pressure
• Osteoporosis
• “Porous bone”
• Is the leading cause of bone fractures in
older adults
Water Content of Various Foods
• As you might
expect, crunchy
vegetables contain
more water than dry
cereal.
• But did you know
that potatoes
contain a high
percentage of
water?
Sports Drinks and Water Absorption
• Drinking plenty of plain water and eating a healthful
diet easily replaces the fluid and electrolytes a person
loses during moderate exercise in pleasant weather.
But if you are involved in endurance activities or
strenuous exercise in hot weather, consider using
sports drinks instead of just plain water.
• Sports drinks contain glucose and electrolytes that
improve the taste, help maintain blood glucose levels,
and enhance absorption.
Calcium
• Calcium is a major component of bones and teeth. In
addition, calcium is required for muscle contraction,
nerve impulse transmission, blood clotting, and regulation
of cell metabolism.
• For adults,1,000 milligrams per day is recommended,
and more is suggested for adolescents and older adults.
Dairy foods and fortified foods are major dietary sources
of calcium.
• Calcium status is regulated by three hormones that
control intestinal absorption, bone calcium release, and
kidney excretion: calcitriol, parathyroid hormone, and
calcitonin. Lack of dietary calcium contributes to the
development of osteoporosis.
Water Intoxication
• Because drinking fluids temporarily alleviates thirst, we
rarely drink to the point of overhydration and dilution of
body fluids. However, replacement of fluid losses following
intensive or prolonged exercise with plain water (and no
electrolytes) can result in overhydration and hyponatremia
(low blood sodium) in athletes.
• Acute water toxicity has been reported due to rapid
consumption of large quantities of fluids that greatly
exceeded the kidney’s maximal excretion rate of
approximately 0.7 to 1.0 liters per hour.
• Several years ago, some dieters overenthusiastically
followed a fad weight reduction diet calling for massive
water intake and suffered seizures from overhydration.
Dietary Guidelines for Americans
• Consume less than 2,300 mg (approximately 1
teaspoon of salt) of sodium per day.
• Choose and prepare foods with little salt. At the same
time, consume potassium-rich foods, such as fruits
and vegetables.
• Key recommendations for specific population groups:
individuals with hypertension, blacks, and middleaged and older adults. Aim to consume no more than
1,500 mg of sodium per day, and meet the potassium
recommendation (4,700 mg/day) with food.
Sources of Dietary Sodium
Banana Facts
• You may know that bananas are high in
potassium, but did you also know that they
have an unusually high-carbohydrate
content?
• Before ripening, a banana is almost entirely
starch. After ripening, certain varieties are
almost entirely sugar—as much as 20
percent by weight.
Food Sources of Potassium
© Photodisc
Effects of Progressive Dehydration
• Dehydration, or too little
water, is a major killer
worldwide—infants and
the frail elderly are
especially vulnerable.
• Gastrointestinal
infections are primarily
responsible.
• Dehydration diminishes
physical and mental
performance.