2Water & the Body Fluids Water Makes up 60% (3/5) of adult’s body weight.Higher for childrenMakes up 75% (3/4) of lean muscle.25% (1/4) of fatMales have more water (more lean muscle)Females, the elderly, obese have less
3Water & the Body Fluids Water in body fluids: Carries nutrients & waste products through the body.Maintains structure of large molecules.Participates in metabolic reactions.Serves as a solvent so substances can participate in metabolic reactions.Acts as a lubricant & cushion around joints, inside eyes, in the spinal cord, & as amniotic sac during pregnancy.Aids in regulation of body temperature.Maintains blood volume.
4Water Balance & Recommended Intakes Fluid inside cellIntracellular fluidFluid outside cellExtracellular fluidInterstitial fluidFluid surrounding cellsComposition between the two differs.Composition in each remains constant under normal conditions.
5Water Balance & Recommended Intakes Water intakeInfluenced by thirst & satietySensed by hypothalamus & nerves.
6Water Balance Dehydration : loss of water & loss not replaced. Symptoms:Water intoxication (rare) : excessive water consumption, may result due to a kidney disorder which reduces the amount of urine produced.SymptomsHyponatremia
8Water Balance Water Sources Nearly all foods contain water Water is produced during cellular respiration & during condensation reactions.
9Water Balances Water losses Body must excrete a minimum of 500 mL (~ 2 cups) of urine a day.ReasonWater is also lostAs sweatFrom lungs as vaporIn fecesAverage daily losses
10Water Balance Water Recommendations Water needs vary depending on diet, environmental conditions, activity, & humidity.Sometimes expressed in proportion to amount of energy expended under average environmental conditions.For a person that expends 2000 kcal a day, the amount is 2 – 3 L (8 – 12 cups).Agrees with AI for total amount set by DRI.If physically active or a hot day, a person will probably need more.
11Water Balance Water Recommendations (continued) Any beverage can meet fluid needs.Caffeinated beveragesCaffeine acts as a diuretic.Causes more water to be lost.People can consume it to meet daily fluid needs, however.AlcoholActs as a diuretic.Should not be used to meet daily fluid needs.
12Water Balance Health Effects of Water Protection against Hard or Soft Water makes a difference
13Water Balance Bottled water – people may think its better & safer. Not necessarily true in US.Distilled waterHas all minerals removed.Natural waterComes from spring or wellMineral content may not be changed.Mineral waterContains more minerals.Minerals give it unique taste.Usually has higher sodium content.
14Blood Volume & Blood Pressure Kidneys are major control for homeostasis of body fluids.Kidneys regulate blood volume which influences blood pressure.Kidneys reabsorb needed substances.Kidneys excrete metabolic wastes with some water.
19Fluid & Electrolyte Balance Dissociation of Salt in WaterMineral salts dissociates (separates) into ions when dissolved in water.Ions -Positive ions called cations.Negative ions called anions.Electrolytes – salts that dissolve in water & dissociate into ions.conduct electrical currents.
20Fluid & Electrolyte Balance Dissociation of Salt in Water (continued)ElectrolyteBalanceMajor extracellular ionsMajor intracellular ions
21Fluid & Electrolyte Balance Electrolytes attract waterWater has net charge of zero.Water is polar moleculeHydrogenOxygen
22Fluid & Electrolyte Balance Water Follows ElectrolytesWater moves across cell membranes when electrolytes move across.OsmosisOsmotic pressure
25Fluid & Electrolyte Imbalances Different Solutes Lost by Different RoutesSolutes lost due to vomiting, sweating, bleeding or diarrheaSodium and chlorideAdrenal gland tumorOversecretion of aldosteroneKidneys may excrete too much potassim.Uncontrolled diabetesExcretion of glucose
26Fluid & Electrolyte Imbalances Replacing Lost Fluids & ElectrolytesNormal replacement of lost fluidsDrink waterSevere casesORT (oral rehydration therapy)
27Acid – Base Balance Ions also regulate acidity of fluids. pH of body ( ) must be maintained otherwise life threatening situations result.ExamplesAcidity is determine by H+3 system defend against pH fluctuations
28Acid-Base Balance Systems to prevent pH fluctuations 1. Regulations by Buffers2. Regulation in the LungsRaising & slowing respiration rate3.Regulation in KidneysReabsorb or excreting bicarbonate.
29The Minerals - Overview InorganicRetain chemical identityRemain in body until excretedCan’t be changed into anything elseCan’t be destroyed by heat, air, acid, or mixing.Body’s Handling of Minerals
30The Minerals - Overview Variable BioavailabilityBindersFound in some foods.Prevent mineral absorptionPhytatesOxalates
31Sodium Sodium Roles in body Sodium & Hypertension Maintains normal fluid electrolyte balanceAssists in nerve impulse conductionAssists in muscle contractionSodium & Hypertension
32Sodium Sodium & Bone Loss Calcium excretion increased with high salt intake.See in summary: p. 397
33Chloride Chloride Roles in Body Maintains normal fluid & electrolyte balance.Part of HCLNecessary for proper digestion
34Potassium Potassium Roles in Body Potassium & Hypertension Maintains normal fluid & electrolyte balance.Assists in may reactions.Supports cell integrityAssists in nerve impulse conduction.Aids in muscle contraction.Potassium & Hypertension
35Calcium Calcium Roles in Body Mineralization of bones & teeth. Involved in muscle contraction & relaxation.Important in nerve functions, blood clotting, blood pressure.
36Calcium Calcium in bones As bones form, calcium forms hydroxyapatite on matrix of collagen.As mineralization continues, bones become denser & stronger.Bones constantly remodeled.Bones gain & lose mineralsChildren gain more than they lose.TeethFormed in similar pattern, but they are not bone.Fluoride hardens & stabilizes the crystals of teeth
37Calcium Calcium in body fluids Extracellular fluids Helps maintain blood pressureReasonAlso participates in blood clotting.Intracellular fluidsBinds to proteins and activates themProteins participate in
38Calcium Calcium & Disease Prevention Calcium & Obesity May protect against hypertension.Calcium & ObesityMay help maintain a healthy body weight.
39Calcium Calcium balance Involves hormones & vitamin D. 3 organs respond whenever blood calcium levels rise or fall.Intestines, bones, kidneysNote figure , p. 401Calcium rigorCalcium tetany
40Calcium Calcium absorption Factors to enhance absorption Acidity of stomach keeps Ca soluble.Vitamin D helps to make the calcium binding protein needed for absorption.Factors that inhibit absorption (many that enhance also inhibit)Lack of stomach acidVitamin D deficiencyHigh phosphorus intakePhytatesOxalates
41Calcium Calcium in Milk Calcium in other foods Calcium most abundant in milkConsequences of drinking too little milk.Calcium in other foodsTofuAlmondsBroccoli
42Calcium Calcium Deficiency Toxicity Symptoms Stunted growth in childrenOsteoporosis in adultsToxicity SymptomsConstipationRisk of kidney stonesInterference with absorption of other minerals.
43Phosphorus Phosphorus Roles in Body Phosphorus Deficiency Mineralization of bones & teethPart of every cellImportant in genetic materialPart of phospholipidsUsed in energy transfer & in buffer systemsPhosphorus DeficiencyMuscular weaaaknessBone pain
44Magnesium Roles in Body Deficiency Bone mineralizaiton Building of proteinsEnyme actionMuscular contractionNerve impulse conductionDeficiencyWeaknessconfusion
45SulfatePart of proteinsStabilizes protein shapeDisulfide bridges