Body fluids compositions, and their measurements By: DR QAZI IMTIAZ RASOOL.
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Body fluids compositions, Body fluids compositions, and their measurementsand their measurements
By: DR QAZI IMTIAZ RASOOLBy: DR QAZI IMTIAZ RASOOL
OBJECTIVESOBJECTIVES
a)Discuss the distribution of total body a)Discuss the distribution of total body H2O (TWB) in the bodyH2O (TWB) in the body
b) List the ionic composition of different b) List the ionic composition of different body compartments body compartments
c) Explain the principles of measurements c) Explain the principles of measurements
Body as an open sytemBody as an open sytemBody exchanges materials and energy
with its surroundings
RouteRoute Range Range (l/day)(l/day)
Regulatory Regulatory influencesinfluences
Insensible - Insensible - lungslungs
0.3-0.40.3-0.4 Atmospheric Atmospheric vapor vapor
pressure pressure (temperature)(temperature)
Insensible - Insensible - skinskin
0.35-0.40.35-0.4 10x increase 10x increase in burn in burn victimsvictims
SweatSweat 0.1-2 (per 0.1-2 (per hour)hour)
Temperature, Temperature, exerciseexercise
FecesFeces 0.1-0.20.1-0.2 Diarrheal Diarrheal diseasedisease
UrineUrine 0.5-1.4-200.5-1.4-20 Body fluid Body fluid compositioncomposition
FACTORS AFFECTINGFACTORS AFFECTINGTotal Body HTotal Body H22OO
varies depending on body fat: varies depending on body fat:
1.1. Infant: 73-80%Infant: 73-80%
2.2. Male adult: 60% Male adult: 60%
3.3. Female adult: 40-50% Female adult: 40-50%
4.4. Effects of obesity Effects of obesity
5.5. Old age 45%Old age 45%
6.6. Climate Level of physical activityClimate Level of physical activity
PERCENTAGE OF H2O IN TISSUES
FLUID COMPARTMENTSFLUID COMPARTMENTS
EXTRA CELLUAREXTRA CELLUAR INTRA CELLULAR INTRA CELLULAR FLUID (cytosol)FLUIDFLUID (cytosol)FLUID
PLASMA PLASMA INTERSTITIAL TRANSCELLULARINTERSTITIAL TRANSCELLULAR FLUID FLUIDFLUID FLUID
1.1. CSFCSF2.2. Intra ocularIntra ocular3.3. PleuralPleural4.4. PeritonealPeritoneal5.5. SynovialSynovial6.6. Digestive SecretionsDigestive Secretions
Average 70 kg person total body weight42 litres total H2O 60% 28 l. Intracellular fluid (ICF) 40%14 l. Extracellular fluid (ECF) 20%
% is important in fluid therapydivided into ¾ ISF and ¼ plasma water
10.5 l. Interstitial fluid (ISF) 15% 3.5 l. Plasma water 5%
PERCENTAGE OF WATER IN TISSUES
Regulation of HRegulation of H22O IntakeO Intake
The hypothalamic thirst center is stimulated:The hypothalamic thirst center is stimulated:
1.1.By a decline in plasma volume of 10%–15%By a decline in plasma volume of 10%–15%
2.2.By increases in plasma osmolality of 1–2%By increases in plasma osmolality of 1–2%
3.3.Via baroreceptor input, angiotensin II, and Via baroreceptor input, angiotensin II, and other stimuliother stimuli
1. Semipermeable membrane
2. Movement some solute obstructed
3. H2O (solvent) crosses freely
4. End point:
1. H2O moves until solute concentration on both sides of the membrane is equal
2. OR, an opposing force prevents further movement
Solutes – dissolved particlesSolutes – dissolved particles
1.1. Electrolytes – charged particlesElectrolytes – charged particles1.1. Cations – positively charged ionsCations – positively charged ions
NaNa++, K, K++ , Ca , Ca++++, H, H++
2.2. Anions – negatively charged ionsAnions – negatively charged ions
ClCl--, HCO, HCO33-- , PO , PO44
3-3-
2.2. Non-electrolytes - Uncharged Non-electrolytes - Uncharged 1.1. Proteins, urea, glucose, OProteins, urea, glucose, O22, CO, CO22
1212
APPROXIMATE IONIC COMPOSITION OF THE BODY H2O COMPARTMENTS
InterstitialH2O
PlasmaH2O
CellH2O
Balance of Starling Forces acting across the capillary Balance of Starling Forces acting across the capillary membranemembrane1.1. osmotic forcesosmotic forces2.2. hydrostatic forceshydrostatic forces
Plasma vs Interstitial SpacePlasma vs Interstitial Space-Balance between Hydrostatic and Colloid Osmotic -Balance between Hydrostatic and Colloid Osmotic
forces across the capillary membranesforces across the capillary membranes
Intracellular vs ExtracellularIntracellular vs Extracellular1.1. Osmotic effect (e.g. electrolytes)Osmotic effect (e.g. electrolytes)2.2. ICFV is ICFV is NOTNOT altered by: altered by: iso-osmotic changesiso-osmotic changes in in
extracellular fluid volume.extracellular fluid volume.
Plasma is clinically accessibleDominated by [Na+] and the associated
anionsUnder normal conditions, ECF osmolarity
can be roughly estimated as:
POSM = 2 [Na+]p 270-290 mOSM
Net Osmotic Force Net Osmotic Force DevelopmentDevelopment
1.1. Semipermeable membrane.Semipermeable membrane.2.2. Movement some solute obstructed.Movement some solute obstructed.
3.3. HH22O (solvent) crosses freely.O (solvent) crosses freely.
4.4. End point:End point:
HH22O moves until solute concentration on both sides of O moves until solute concentration on both sides of the membrane is equal.the membrane is equal.
OROR, an opposing force prevents further movement., an opposing force prevents further movement.
Ionic composition very different-Total ionic concentration very similar-Total osmotic concentrations virtually identical
Disorders of HDisorders of H22O Balance: DehydrationO Balance: Dehydration
Excessive loss of H2O from ECF
1 2 3ECF osmotic pressure rises
Cells lose H2O to ECF by osmosis; cells shrink
(a) Mechanism of dehydration
ECF Osmolarity ECF Osmolarity ??1.1. HH22O moves out of cellsO moves out of cells
2.2. ICF Volume decreases ICF Volume decreases (Cells shrink)(Cells shrink)
3.3. ICF Osmolarity increasesICF Osmolarity increases
4.4. Total body osmolarity Total body osmolarity remains higher than remains higher than normalnormal
ECF Osmolarity ??
1.1. HH22O moves into the O moves into the
cellscells2.2. ICF Volume increases ICF Volume increases
(Cells swell)(Cells swell)
3.3. ICF Osmolarity ICF Osmolarity decreasesdecreases
4.4. Total body osmolarity Total body osmolarity remains lower than remains lower than normalnormal
CRITERIA FOR A SUITABEL DYE.CRITERIA FOR A SUITABEL DYE.BODY FLUID MARKERBODY FLUID MARKER
1. Must mix evenly throughout the compartment
2. Non toxic, no physiological activity
3. Even mixing
4. Must have no effect of its own on the distribution of H2O or other substances in the body
5. Either it must be unchanged during the experiment or if it changes , the amount changed must be known.
6. The material should be relatively easy to measure.
DILUTION PRINCIPLEDILUTION PRINCIPLE
Inject x gm x gm of marker into compartment
measure concentration at equilibrium (y gm/L) (y gm/L)
Since concentration = mass/ volume
Volume = mass / concentration Volume = mass / concentration = x/y L= x/y L
C1V1=C2V2
Principle of mass conservationPrinciple of mass conservationBased on using a marker whose concentration can be measured.
Measuring Compartment Measuring Compartment Size Size Indirect METHOD Indirect METHOD – INDICATOR (DYE) DILUTION TECHN– INDICATOR (DYE) DILUTION TECHNIQUE
(Law of Mass Conservation) (Law of Mass Conservation)
Concentration = Amount InjectedVolume of Distribution
Amount of Tracer Remained in Compartment = A - ECompartment Volume = (A – E)/C
Compartment
Volume (V)
Tracer Concentration (C)Amount of Tracer Added(A)
Amount ofTracer LostFrom Compartment(E)
Based on concentration in a well-mixed substance that distributes itself only in the compartment of interest.
Indicators used for measuring plasma Indicators used for measuring plasma volume, ECF volume and total body Hvolume, ECF volume and total body H22OO
CompartmentCompartment CriterionCriterion IndicatorsIndicators
1.1. PlasmaPlasma Substance Substance should not cross should not cross capillariescapillaries
1.1. Evans blue dye; Evans blue dye;
2.2. radioiodinated fibrinogen; radioiodinated fibrinogen;
3.3. radioiodinated albuminradioiodinated albumin
1.1. ECF ECF volumevolume
Substance Substance should cross should cross capillaries but capillaries but not cross cell not cross cell membranesmembranes
Isotonic solutions of sucrose, Isotonic solutions of sucrose, inulin, mannitol, NaClinulin, mannitol, NaCl
1.1. Total Total body Hbody H22O O
(TBW)(TBW)
Substance Substance distributes distributes evenly in ICF & evenly in ICF & ECFECF
Heavy H2O, tritiated H2O, Heavy H2O, tritiated H2O, aminopyrine, antipyrineaminopyrine, antipyrine
Total Body HTotal Body H22O (TBW)O (TBW)
1.1. Deuterated H2O (DDeuterated H2O (D22O)O)
2.2. Tritiated H2O (THO)Tritiated H2O (THO)
3.3. AntipyrineAntipyrine
Blood volume /Markers usedBlood volume /Markers used1.1. Obtained from plasma volume and hematocritObtained from plasma volume and hematocrit2.2. Total blood volume = Plasma volume/1- Total blood volume = Plasma volume/1-
HematocritHematocrit3.3. Example: If the plasma volume is 4 liters and the Example: If the plasma volume is 4 liters and the
hematocrit is 0.45, total blood volume is ?hematocrit is 0.45, total blood volume is ?4.4. =PLASME VOL X 100=PLASME VOL X 100
100 -HCT100 -HCT
1.T-1824 (Evans blue dye) attaches to plasma proteins and is removed by the liver. Measures plasma volume
2. 2. Radioactive labeled 125 i albumin 3. Cr51 (radioactive chromium) is incubated with red
blood cells then injected Measures total blood volume
Take this problem:Take this problem:100 mg of sucrose is injected into a 70 100 mg of sucrose is injected into a 70
kg man. The plasma sucrose level kg man. The plasma sucrose level after mixing is 0.01 mg/ml. If 5 mg after mixing is 0.01 mg/ml. If 5 mg has been metabolized during this has been metabolized during this period, then, what is the ECF volume?period, then, what is the ECF volume?
9.5 L9.5 L
14 L14 L
17.5 L17.5 L
10 L10 LIf 1mL of solution (10mg/mL) of dye is dispersed in chamber B and final concentration is the
chamber is 0.01mg/mL. What is the volume in chamber B?
1000ml or 1L
Compartments withCompartments with no no Compartment-Specific Compartment-Specific
SubstanceSubstance1.1. Determine by subtraction:Determine by subtraction:2.2. How would you measure ICF volume?How would you measure ICF volume?3.3. Cannot be measured; it is calculated Cannot be measured; it is calculated
(estimated)..(estimated)..4.4. ICF volume = Total body HICF volume = Total body H22O – ECF volumeO – ECF volume
5.5. Interstitial volumeInterstitial volume1.1. Can not be measured directlyCan not be measured directly
6.6. Interstitial Fluid Volume (ISFV).Interstitial Fluid Volume (ISFV).ISFV = ECFV - PVISFV = ECFV - PV
Measurement of other spacesMeasurement of other spaces
Extracellular volumeNa24
Cl35
Inulin Sucrose Mannitol Sulfate I125 iothalamate
Disperse in plasma and interstitial fluid, but not permeable to cell membrane
30-60 min for dispersion to extracellular fluid
Determining body fat:Determining body fat:
Technique: Technique: bioelectric impedance bioelectric impedance techniquetechnique
Principle: Principle: 1.1. Body fluids conduct electricity well;Body fluids conduct electricity well;
2.2. But fat is anhydrous and therefore is a But fat is anhydrous and therefore is a poor conductor of electricity;poor conductor of electricity;
3.3. The resistance to flow of a small The resistance to flow of a small current between points on the body is current between points on the body is proportional to fat mass.proportional to fat mass.
Lean body mass (LBM)Lean body mass (LBM)
Definition: LBM is fat free massDefinition: LBM is fat free mass
Total body mass = fat mass + fat free massTotal body mass = fat mass + fat free mass
Note: fat is relatively anhydrousNote: fat is relatively anhydrous
Note: the HNote: the H22O content of LBM is constantO content of LBM is constant
HH22O content of LBM is constant - 70 ml /100 g O content of LBM is constant - 70 ml /100 g
tissuetissue
Take this problemTake this problem::
In a healthy adult male weighing 70 kg, total In a healthy adult male weighing 70 kg, total body Hbody H22O (TBW) was measured to be 42 L. O (TBW) was measured to be 42 L. What is his lean body mass (LBM)? What is What is his lean body mass (LBM)? What is his fat mass? his fat mass? 1.1. Given TBW = 42 LGiven TBW = 42 L
2.2. Assume all this HAssume all this H22O is in LBM & that fat is O is in LBM & that fat is HH22O freeO free
3.3. We know that HWe know that H22O content of LBM is 70 O content of LBM is 70 ml/100 gml/100 g
4.4. Thus, if TBW is 42 L, LBM = 60 kgThus, if TBW is 42 L, LBM = 60 kg
5.5. Since he weights 70 kg, his fat mass is 70-60 Since he weights 70 kg, his fat mass is 70-60 = 10 kg= 10 kg
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