ASSIGNMENTASSIGNMENT MEDICALMEDICALPHYSIOLOGYPHYSIOLOGY

TitleTitle MEASUREMENTS OF THE MEASUREMENTS OF THE

DIFFERENTS BODY FLUIDSDIFFERENTS BODY FLUIDS

BY: IRFAN MUHAMMADBY: IRFAN MUHAMMADROLL NO # 2012013025ROLL NO # 2012013025

CLASS: F2012 (1)CLASS: F2012 (1)

Measurement of Fluid Volumes in the Different Body Fluid Compartments—the Indicator-Dilution PrincipleIn this Principle, a small amount of dye or other substance contained in the syringe is injected into a chamber and the substance is allowed to disperse throughout the chamber until it becomes mixed in equal concentrations in all areas. Then a sample of fluid containing

Then a sample of fluid containing the dispersed substance is removed and the concentration is analyzed chemically, photoelectrically, or by other means. If none of the substance leaks out of the compartment.

The volume of a fluid compartment in the body can be measured by placing an indicator substance in the compartment, allowing it to disperse evenly throughout the compartment’s fluid, and then analyzing the extent to which the substance becomes dilute this “indicator-dilution” method of measuring the volume of a fluid compartment.

This method is based on the conservation of mass principle, which means that the total mass of a substance after dispersion in the fluid compartment will be the same as the total mass injected into the compartment.

The total mass of substance in the compartment (Volume B × Concentration B) will equal the total mass of the substance injected (Volume A × Concentration A). By simple rearrangement of the equation, one can calculate the unknown volume of chamber B as demonstrate in followings

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 ionsClCl--, HCO, HCO33

-- , PO , PO443-3-

2.2. Non-electrolytes - Uncharged Non-electrolytes - Uncharged 1.1. Proteins, urea, glucose, OProteins, urea, glucose, O22, CO, CO22

2020

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 cells2.2. 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 decreasesICF Osmolarity decreases

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 compartmentmeasure 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 L14 L14 L17.5 L17.5 L10 L10 L

If 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 spacesExtracellular volume

Na24

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 massTotal body mass = fat mass + fat free massTotal body mass = fat mass + fat free massNote: fat is relatively anhydrousNote: fat is relatively anhydrousNote: 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