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WATER. WATER. Essential nutrient – NO calories Part of every cell muscle 75% bones 25% teeth 10% fat tissue 20-33% Higher body fat = Less H2O Higher lean = Higher H2O. WATER COMPARTMENTS. WATER. Do not store water How long can we survive without water?
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WATER • Essential nutrient – NO calories • Part of every cell muscle 75% bones 25% teeth 10% fat tissue 20-33% Higher body fat = Less H2O Higher lean = Higher H2O
WATER • Do not store water • How long can we survive without water? • Water varies by: Age – caused by loss of extracellular fluid embryo = ~97% newborn = ~75% adult = ~60% elderly = ~<60% (~50%) Gender- because of LBM relationship Men = 60% of body weight Women = 50% of body weight
FUNCTIONS • Building material – part of every cell • Medium for chemical reactions – chemicals (enzymes, hormones, coenzymes) dissolve and act on metabolites • Hydolysis – digestion • Transport medium – solvent for waste products • Lubricant – water filled sacs around joints • Shock absorber – around brain and spinal cord • Temperature control – cools skin, excess heat from metabolic reactions • Blood volume
FLUID BALANCE • Fluid loss • Concentration of electrolytes • Water absorbed from saliva • Dry mouth, thirst stimulated • Children, elderly, athletes
WATER LOSSES • Normal 2-3 liters/day • Urine = 500-1400 ml • Skin = 450-900 ml • Lungs = 350 ml • Feces = 150 ml • Insensible losses (skin, lungs, feces) • GI tract 8 liters/day secreted as digestive juices reabsorbed in colon
LOSSES INCREASED • Alcohol • Caffeine • Diuretics
OUTPUT DEPENDS ON • Total intake • Metabolic disturbances • Altered dietary intake: protein, NaCl, CHO increase urine output for urea, ketones, and Na • Output of 1 liter/day = concentrated urine increased risk of stones in susceptible people
WATER SOURCES • Fluids = 550-1500 ml • Solid food = 700-1000 ml • Metabolic water = 200-300 ml • Needs = losses • Input and output normally in equilibrium • Obligatory waste excretion – need at least 500 ml to excrete metabolic wastes
DEHYDRATION – LOW WATER LEVELS • Physical causes: • Vomiting • Diarrhea • Blood loss • Fever • Weight loss • Work in high temperatures/hot climates • Strenuous physical exercise
SYMPTOMS • Thirst – not always reliable • Loss of appetite • Decreased blood volume • Impaired physical performance • Impaired temperature regulation • Muscle spasms • General debilitation
LAB TESTS TO DIAGNOSE • Increased hematocrit • Increased serum sodium • Increased albumin • Increased BUN
WATER LOSSES • 3% of body weight decreased physical performance • 4-5% body weight impaired mental function • 10% of body weight life threatening • 20% body weight fatal
REHYDRATION • Drinking enough fluid? color of urine volume of urine weight loss • For every pound lost drink 2 cups of fluid • During exercise – 1 quart fluid for every 1000 cal spent drink 8-10 ounces every 15-20 min. of strenuous exercise – may sweat 3 times that much • At risk for Na depletion if longer than 4 hour workout – athletes acclimate, sweat less salty as become more conditioned
WHAT TO DRINK • ? Caffeine - increases urination • ? Soft drinks - empty calories • ? Gatorade, Allsport, Powerade - little nutritional value • ? Beer - ETOH dehydrating effect, increase urination • ? Juice Vit C and K • ? Water • ? Glucose polymers & CHO powders – can provide energy value with less sweetness • ? Salt tablets – increase dehydration
WATER INTOXICATION • Kidneys are overwhelmed – can’t excrete fast enough • Caused by Greatly increased water intake Increased secretion of antidiuretic hormone Acute weight gain • Physical symptoms Headaches Blurred vision Cramps Eventually convulsions
LABORATORY SIGNS • Decreased hematocrit • Decreased serum sodium • Decreased albumin • Decreased BUN • Excess water dilutes Na decreases Na concentration in ECF water enters cells and upsets balance