Chapter 8

Learning Outcomes for Chapter 8

• 8.1 Explain the importance and functions of water in the body.

• 8.2 Describe water balance and how the body maintains it.

• 8.3 Identify daily water needs and the best sources for it.

• 8.4 Explain what minerals are and why you need them.

• 8.5 Name functions, sources, and deficiency/toxicity symptoms of:

  • Sodium

  • Potassium

  • Calcium

  • Phosphorus

  • Magnesium

  • Chloride

  • Sulfur

  • Iron

  • Copper

  • Zinc

  • Selenium

  • Fluoride

  • Chromium

  • Iodine

  • Manganese

  • Molybdenum

Importance of Water in the Body (1 of 2)

• Abundance:

  • Water is the most abundant substance in the body, constituting about 60% of a healthy adult.

  • Muscle tissue consists of 75% water, while fat comprises about 20% water.

  • Survival without water is a few days, indicating its crucial role.

• Fluid compartments:

  • Intracellular fluids: located within cells.

  • Extracellular fluids: consist of interstitial fluid and blood plasma.

• Electrolytes:

  • Essential minerals that help maintain fluid balance in the body.

Importance of Water in the Body (2 of 2)

• Role as a universal solvent:

  • Facilitates chemical reactions in the body.

  • Transports oxygen, nutrients, and hormones to cells via blood.

  • Assists in removing waste products through interstitial fluid.

• Temperature regulation:

  • Water helps maintain body temperature through sweat and blood circulation.

• Lubrication and cushioning:

  • Serves as a lubricant for joints and eyes and is a component of mucus and saliva.

  • Provides a protective cushion for the brain and organs.

Water Balance and Maintenance

• Definition of water balance:

  • Water intake equals water loss.

• Water intake:

  • Sources include beverages and food.

• Water loss:

  • Occurs through kidneys (urine), large intestine (feces), lungs, and skin.

  • Insensible water loss: Evaporation from the skin and exhalation.

  • Sensible water loss: Through urine, feces, and sweat.

Daily Water Needs

• Influencing factors:

  • Varies based on physical activity, environment, and diet.

• Recommendations:

  • Men: approximately 16 cups/day (13 cups from beverages)

  • Women: about 12 cups/day (9 cups from beverages)

  • About 80% of total water intake should come from beverages and 20% from foods.

Dehydration

• Causes:

  • Inadequate water intake or excessive water loss (diarrhea, vomiting, high fever, diuretics).

• Thirst mechanism:

  • Signals dehydration; dry mouth and reduced blood volume trigger drinking behavior and hormone regulatory mechanisms.

• Detection methods:

  • Measure weight before and after exercise (weight loss indicates water loss).

  • Monitor urine color (dark color signifies dehydration).

Hyponatremia

• Definition:

  • Condition of low sodium levels in the blood due to excessive water consumption.

• Affected group:

  • Sometimes seen in soldiers, endurance athletes during intensive training.

Overview of Minerals

• Definition of minerals:

  • Inorganic elements required in small amounts.

  • Bioavailability affects absorption:

    • Competition among minerals (e.g., excess zinc can impair copper absorption).

    • Some compounds (e.g., oxalates in spinach) can inhibit mineral absorption.

• Categories:

  • Major (macrominerals): Required in amounts greater than 100 mg/day (e.g., sodium, potassium, calcium).

  • Trace (microminerals): Required in amounts less than 15 mg/day (e.g., iron, copper, zinc).

Summary of Major Minerals

Summary of Trace Minerals