Chapter 10

1. Chapter 10 Water and the Electrolytes

2. Water: The Internal Sea • Functions of water in the body • Solvent • Lubricator • Transporter • Regulates temp & pH (7.4)

3. Distribution of Body Water • In adults, ~ 60% of total body weight • Intracellular fluid: ~2/3 water inside cells • Extracellular fluid: ~1/3 water outside cells 10-9

4. Movement of Water • Osmosis: movement of water to balance the concentration of solvent 10-10

5. Water Balance Intake = Output 10-11

6. The Water Content of Foods

7. Regulation of Water Intake • Signals from the brain (hypothalamus) • Dry mouth motivate the consumption of fluid

8. Regulation of Water Losses • Antidiuretic hormone (ADH): • acts on kidneys to increase water reabsorption 10-14

9. Recommended Water Intake • DRI: • Men: 3.7 liter/day • Women: 2.7 liter/day • Activity, heat, humidity, and diet • Pregnancy & lactation needs increased 10-15

10. Water Deficiency: Dehydration • Adverse effects

11. Water Toxicity: Overhydration • May occur with illness • Too much plain water is used to replenish lost sweat • Causes electrolyte imbalance

12. ELECTROLYTES

13. Electrolytes • Electrolytes: mineral salts that dissociate in water to form charged ions • Sodium, Chloride, and Potassium • Functions: • Fluid balance: affects water distribution • Nerve functions • Muscle contractions

14. Electrolytes in our diet • Processed foods: sodium • Fresh foods: potassium

15. Regulation of Electrolyte Balance • Sodium: regulates extracellular fluid volume • Potassium: regulates intracellular fluid volume • Homeostasis is regulated by the intake of both water and salt 10-22

16. Electrolyte Deficiency • Heavy and persistent sweating, chronic diarrhea or vomiting • Deficiencies of any of the electrolytes  electrolyte imbalance • Symptoms: poor appetite, muscle cramps, confusion, & irregular heart beat 10-25

17. Electrolyte Toxicity • Excess salt intake excreted by the kidneys • In salt-sensitive individuals, the regulatory mechanisms are unable to prevent rises in blood pressure as salt intake increases • High risk for hypertension 10-26

18. Sodium & blood pressure • Water follows salt • Salt intake  blood volume increases  blood pressure increases • What happens when blood pressure is low?

19. Sodium and Blood Pressure Control 10-23

20. Hypertension: “The Silent Killer” • Optimal (Systolic): 90-120 mm Hg • High blood pressure: 140/90 mm Hg or higher • What causes hypertension? • Disturbances in the mechanisms that control body fluid and electrolyte balance 10-27

21. Risk Factors of Hypertension • Genetics: Family history, ethnic & racial background • Age • Conditions: Diabetes, kidney damage, obesity • Lifestyle: Physical activity, heavy alcohol consumption, smoking, stress,

22. Diet and Blood Pressure • High salt intake • Increases risk in salt sensitive people • Potassium, calcium, & magnesium intake • Lowers incidence of hypertension • What type of diet would you recommend? 10-30

23. D.A.S.H. • Dietary Approaches to Stop Hypertension • A diet high in fruits &vegetables, low in fat • DASH Trial

24. Preparing a 1 (one) litre oral rehydration solution [ORS] using Salt, Sugar and Water at HomeMix an oral rehydration solution using  one of the following recipes; Ingredients: • one level teaspoon of salt • eight level teaspoons of sugar • one litre of clean drinking or boiled water and then cooled5 cupfuls (each cup about 200 ml.) • Preparation Method: • Stir the mixture till the salt and sugar dissolve.

25. Objectives • Functions of water • Regulation of water intake & loss • Define and name major electrolytes • Functions of electrolytes • Role of Na in blood pressure • Diet modification for high blood pressure