Chapter 8, Part 2 Water Balance 1. Key Concepts Water compartments inside and outside of cells...
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Transcript of Chapter 8, Part 2 Water Balance 1. Key Concepts Water compartments inside and outside of cells...
Chapter 8, Part 2Chapter 8, Part 2Water Balance
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Key ConceptsKey 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.
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Key ConceptsKey Concepts
Humans can live 1 month w/o foodHumans can live only 6 days w/o waterBody weight is over ½ waterMale body: 60% - 65% waterFemale body: 50% - 54% waterInfants body: 75% waterPremature infants: 80% water
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Fluid compartmentsFluid 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)
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Fluid CompartmentsFluid CompartmentsCopyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 5
Body Water FunctionsBody Water Functions
Solvent◦Basic liquid solvent for all chemical
processes within the bodyTransport
◦Nutrients carried through the body in water-based fluids (e.g., blood, secretions)
Thermoregulation◦Maintains stable body temperature
Body lubricantGives body shape and form
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Body Water RequirementsBody 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 activityFunctional losses
◦Disease process affects water requirements, ie: vomiting, diarrhea, fever, diuretic use
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Body Water Requirements, cont’dBody Water Requirements, cont’d
Metabolic needs◦1000 ml of water necessary for every 1000
kcal in the dietAge
◦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
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Other Dietary FactorsOther 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 intakeWater intoxication (excess intake, can
cause hyponatremia – low Na) Elderly, psych pts., use of psychotropic drugs,
prolonged extreme exercise
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Percentage of Body Weight LossPercentage of Body Weight LossCopyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 10
Water BalanceWater 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
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Water BalanceWater Balance
Daily Weight = single most important indicator of fluid balance
1 kg = 2.2 lbs.Intake and Output should be almost equal
in healthy individualExcessive fluid volume: hypervolemia, I > O, edema, respiratory distressInsufficient fluid volume: dehydration,
hypovolemia, O > I, Low BP
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ElectrolytesElectrolytes
Small, inorganic substances that break apart in a solution and carry an electrical charge (ions)
Cation + charge, Na, K, Ca, MgAnion – charge, Cl, HCO3, PO4, SO4Maintain electrochemical processes and
balance between extracellular/intracellular fluid
Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 13
Organ Systems Involved in Body Organ Systems Involved in Body Water BalanceWater 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.
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Organ Systems Involved in Body Organ Systems Involved in Body Water Balance, cont’dWater Balance, cont’d
Renal circulation◦Kidney - filters the blood (“cleans the blood”) to
help maintain water balance and electrolyte balance
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SummarySummary
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
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