Bi_233_ch26_fluid__electrolyte__and_acid-base_balance_part_1.pdf

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Chapter 26: Fluid, Electrolyte, and Acid-Base Balance1Chapter 26Bi 233Fluid, Electrolyte, and AcidBase BalanceBody Water ContentLargest component of the bodyInfants have low body fat, low bone mass, and are 73% ormore waterHealthy males are about 60% water; healthy females arearound 50%This difference reflects females’:Higher body fatSmaller amount of skeletal muscleTotal water content declines throughout lifeIn old age, only about 45% of body weight is water
Chapter 26: Fluid, Electrolyte, and Acid-Base Balance2Fluid CompartmentsWater occupies two (or three) main fluid compartmentsIntracellular fluid (ICF) – about two thirds by volume,contained in cells~25 LExtracellular fluid (ECF) – consists of two majorsubdivisions~15 LIntersXXal fluid (IF) – fluid in spaces between cells80% of ECF ~10‐12 LPlasma – the fluid porXon of the blood20% of ECF ~3‐5 LFluid CompartmentsFigure 26.1
Chapter 26: Fluid, Electrolyte, and Acid-Base Balance3Composi4on of Body FluidsWater is the universal solventSolutes are broadly classified into:Electrolytes – ionic (caXons or anions)Inorganic salts, all acids and bases, and some proteinsYield two or more solute parXcles when dissolved in soluXonNaClNa++ ClCaCl2Ca+++ 2ClNonelectrolytes – covalentGlucose, lipids, creaXnine, and ureaElectrolytes have greater osmoXc power than nonelectrolytesWater moves according to osmoXc gradientsExtracellular and Intracellular FluidsEach fluid compartment of the body has a disXncXve paaern ofelectrolytesExtracellular fluids are similar (except for the high protein content ofplasma)Na+primary caXonAlso Ca2+Clprimary anionAlso HCO3Plasma has many more protein and sodium anions but fewerchloride ions than intersXXal fluidMore proteins in intracellular than extracellular fluid
Chapter 26: Fluid, Electrolyte, and Acid-Base Balance4Extracellular and Intracellular FluidsIntracellular fluids have low sodium and chloridePotassium primary caXonAlso magnesium Mg2+Phosphate primary anionAlso hydrogen phosphateHPO4Sodium and potassium concentraXons in extra‐ andintracellular fluids are nearly oppositesDue to cellular ATP‐dependent sodium‐potassium pumpsExtracellular and Intracellular FluidsProteins, phospholipids, cholesterol, and neutralfats account for:90% of the mass of solutes in plasma60% of the mass of solutes in intersXXal fluid97% of the mass of solutes in the intracellularcompartment
Chapter 26: Fluid, Electrolyte, and Acid-Base Balance5Electrolyte Composi4on of Body FluidsFigure 26.2Fluid Movement Among CompartmentsFluid exchange between compartments is conXnuousRegulated by osmoXc and hydrostaXc pressuresAny change in solute concentraXon leads to net watermovementECF greater impact than ICF

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Term
Spring
Professor
BJ Page
Tags
Sodium, ECF

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