1. Chapter 8, Part 2 Water Balance 1

2. Key Concepts Water compartments inside and outside of cells maintain a balanced distribution of total body water. The human body forms one continuous body of water contained by a protective envelope of skin. Water moves to ALL parts of the body. 2

3. Key Concepts Humans can live 1 month w/o food Humans can live only 6 days w/o water Body weight is over ½ water Male body: 60% - 65% water Female body: 50% - 54% water Infants body: 75% water Premature infants: 80% water 3

4. Fluid compartments Intracellular Fluid ◦Fluid inside cells ◦Adults = 65% of body water is intracellular Extracellular Fluid ◦Fluid outside cells ◦Adults = 35% of body water is extracellular ◦Interstitial (between cells), intravascular (in blood vessels), lymph (immune system) 4

5. Fluid Compartments Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.5

6. Body Water Functions Solvent ◦Basic liquid solvent for all chemical processes within the body Transport ◦Nutrients carried through the body in water- based fluids (e.g., blood, secretions) Thermoregulation ◦Maintains stable body temperature Body lubricant Gives body shape and form 6

7. Body Water Requirements Include water in food and beverages ◦Usual = 80% from fluids ◦20% from foods Dependent upon activity level ◦Water is lost as sweat ◦More water is needed for increased metabolic demand in physical activity Functional losses ◦Disease process affects water requirements, ie: vomiting, diarrhea, fever, diuretic use 7

8. Body Water Requirements, cont’d Metabolic needs ◦1000 ml of water necessary for every 1000 kcal in the diet Age ◦Infants need 700 to 800 ml of water per day ◦ 3 cups ◦Adults need 2000ml to per day to maintain hydration (food and beverage) ◦ 8-12 cups 8

9. Other Dietary Factors Dehydration ◦Excessive loss of total body water ◦>2% total body weight loss (>20% fatal) ◦Thirst, headache, dizziness, decreased UO, dry mouth, low BP, kidney failure ◦Special concern in the elderly – decreased thirst sensation, low intake Water intoxication (excess intake, can cause hyponatremia – low Na)  Elderly, psych pts., use of psychotropic drugs, prolonged extreme exercise 9

10. Percentage of Body Weight Loss Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.10

11. Water Balance 80% water from beverages ◦Skim milk = 91% water 4 cups/day water from foods ◦Lettuce, celery, vegetables, fruits Water Losses ◦1. Sensible: perspiration, urine, feces ◦2. Insensible: lungs, skin 11

12. Water Balance Daily Weight = single most important indicator of fluid balance 1 kg = 2.2 lbs. Intake and Output should be almost equal in healthy individual Excessive fluid volume: hypervolemia, I > O, edema, respiratory distress Insufficient fluid volume: dehydration, hypovolemia, O > I, Low BP 12

13. Electrolytes Small, inorganic substances that break apart in a solution and carry an electrical charge (ions) Cation + charge, Na, K, Ca, Mg Anion – charge, Cl, HCO3, PO4, SO4 Maintain electrochemical processes and balance between extracellular/intracellular fluid Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.13

14. Organ Systems Involved in Body Water Balance Gastrointestinal circulation ◦Water from blood plasma is continually secreted into the gastrointestinal tract. ◦In the latter portion of the intestine, most water and electrolytes are reabsorbed into the blood. 14

15. Organ Systems Involved in Body Water Balance, cont’d Renal circulation ◦Kidney - filters the blood (“cleans the blood”) to help maintain water balance and electrolyte balance 15

16. Summary The human body is approximately 50% to 60% water (men have more) Primary functions of water are to give form and structure to body tissue, provide a water environment for cells to work, and control body temperature Body water is distributed within the intracellular and extracellular compartments 16