WaterWater

WaterWater

• essentialessential

• 60% body weight: influenced 60% body weight: influenced by body compositionby body composition

– 75% of lean tissue is water75% of lean tissue is water

– < 25% of fat is water< 25% of fat is water

Fluid between thecells (intercellularor interstitial)

Fluid within thecell (intracellular)

WaterWater

• carries nutrients and wastescarries nutrients and wastes

• maintains molecule structuremaintains molecule structure

• involved in metabolisminvolved in metabolism

• solventsolvent

• lubricantlubricant

• aids in regulation of body tempaids in regulation of body temp

• blood volumeblood volume

Water IntakeWater Intake

• thirst and satietythirst and satiety– blood becomes concentrated – blood becomes concentrated –

mouth becomes drymouth becomes dry– hypothalamus initiates drinkinghypothalamus initiates drinking– stomach and heart receptors stomach and heart receptors

indicateindicate• fullnessfullness• OK blood volumeOK blood volume

Water IntakeWater Intake

• thirst lags behind the thirst lags behind the body’s needsbody’s needs

• dehydrationdehydration

– water output water output exceeds water inputexceeds water input

Water SourcesWater Sources

• waterwater

• fruits/vegetables = up to 90% waterfruits/vegetables = up to 90% water

• meats and cheeses = 50% watermeats and cheeses = 50% water

• generated during metabolismgenerated during metabolism

– breakdown of C and H combine with Obreakdown of C and H combine with O

• COCO22 and H and H2200

Water LossesWater Losses• 500 ml a day for urine500 ml a day for urine• any more is adjusted by the kidney to any more is adjusted by the kidney to

maintain balancemaintain balance• water is also lost fromwater is also lost from– lungslungs– sweatsweat– fecesfeces

• amount varies dependent on environment amount varies dependent on environment and physical conditionand physical condition

Water RecommendationsWater Recommendations

• Adequate IntakeAdequate Intake

– men - 3.7 L/daymen - 3.7 L/day

– women - 2.7 L/daywomen - 2.7 L/day

• 2000 kcal/day – 2-3 L/day (7-11 cups)2000 kcal/day – 2-3 L/day (7-11 cups)

– drinking water, other beverages and drinking water, other beverages and foodfood

Water RecommendationsWater Recommendations

• change depending on environment and change depending on environment and physical conditionphysical condition

• need to be replenished dailyneed to be replenished daily

WaterWater• soft watersoft water

– salt salt

– easily dissolves contaminant easily dissolves contaminant mineralsminerals

• hard waterhard water

– calciumcalcium

WaterWater

• blood volumeblood volume

– hormones and enzymes are key players hormones and enzymes are key players in the retention or release of substances in the retention or release of substances or water from the bodyor water from the body

ElectrolytesElectrolytes

• a mineral salt dissolves in watera mineral salt dissolves in water

• separates into ionsseparates into ions

– positive (cation) and negative (anion)positive (cation) and negative (anion)

– electrolyteselectrolytes

• remains balancedremains balanced

Electrolytes attract waterElectrolytes attract water

• salt are dissolved in the watersalt are dissolved in the water

– moves fluids into cells and outside of moves fluids into cells and outside of cells (water follows the electrolytes)cells (water follows the electrolytes)

• maintains water balancemaintains water balance

• maintains acid-base balancemaintains acid-base balance

Fluid ImbalanceFluid Imbalance

• body can easily regulatebody can easily regulate

• extreme situations require interventionextreme situations require intervention

– heavy sweatingheavy sweating

– burnsburns

– severe and prolonged vomiting and severe and prolonged vomiting and diarrheadiarrhea

Acid-Base BalanceAcid-Base Balance

• metabolism generates hydrogen ions (H+)metabolism generates hydrogen ions (H+)

– acidicacidic

– must be neutralizedmust be neutralized

• blood buffersblood buffers

• respiration in the lungsrespiration in the lungs

• excretion in the kidneysexcretion in the kidneys