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DYNAMIC EQUILIBRIUM OF BODY

FLUID

DENNY AGUSTININGSIH

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BODY FLUIDS FUNCTIONS Main Functions:

Solvent

Transport

Other Functions:

Give shape and form to the cells

Regulate body temp.

Joint lubricant

Cushion body organs

Maintain peak performance

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In average young adult male:

% of body weightBody composition

18%Protein, & related substances

15%Fat

7%Mineral

60%Water

Body composition

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Factors affecting body fluids volume

Water intake & output Age:

- infant: 73%- elderly: 45%

Sex:- adult male: 60%- adult female: 40-50%

Body temperature healthy adult can sweat 1

liter/hr for 2 hrs (5% ofbody wt without problem)

perspire (1000cc wet sheet) Every degree F = 75 ml

increase/day in fluid needs

Obesity Climate Habits

Level of physical activity

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Body Fluid Compartments

Intracellular(ICF)

Extracellular(ECF)

Interstitial

Plasma

Figure 5-13: Body fluid compartments

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Total Body Fluid by Compartment

Total Body Water

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COMPOSITION OF BODY FLUIDS

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Normal Electrolytes Composition during

resting condition

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Differences between ECF & ICF

ECFAnions:Cl- (108)

HCO3-(24)

Cations:

Na+ (142mmol/L)

K+ (4.2)

Mg2+ (0.8)

Nutrients:

O2, glucose, fatty acids, &

amino acids.

Wastes:

CO2, Urea, uric acid,

excess water, & ions.

ICFAnions:Cl- (4)

HCO3-(10)Phosphate ions

Cations:

Na+

(14)

K+ (140)

Mg2+ (20)

Nutrients:

High concentrations of proteins.

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Daily Water Gain and Loss

Copyright 2009, John Wiley & Sons, Inc.

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HOMEOSTASIS Claude Bernard (1878): animals have 2 environments

- milieu exteriur : physically surrounds the wholeorganism

- milieu interieur : surrounds the tissue and cells of theorganism

organic liquid

homeostasis

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HOMEOSTASIS Parameters of the milieu interieur that must be tightly

controlled

- core temperatures

- levels of oxygen - glucose

- potassium ions

- calsium ions

- hydrogen ions

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TRANSPORT OF BODY WATER AND SOLUTE

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Volume ContractionIsotonic Hypertonic Hypotonic

ECF

ECF

ICFECF

ICF

Osmolality

Volume Expansion

Isotonic Hypertonic Hypotonic

ECF

ICFECF

ICFECF

ICF

Osmolal

ity

From H. Valtin

ICF

PATHOPHYSIOLOGICAL CHANGES INEXTRACELLULAR FLUID VOLUME

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CONTROL OF WATER INTAKE

Primarily by THIRST

Stimuli:

1) Increased Osmolality

2) Decreased Arterial Pressure3) Decreased Blood Volume4) Angiotensin II

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HOW CAN WE FEEL THIRSTY?

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WHEN DO WE FEEL A SENSE OF THIRST ?

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Changes in the osmolality of

plasma lead toAVP secretionat a much lower thresholdthan they lead to thirst

Very small increases in AVPlead to very large changes in

urine volume

Thus the kidney is the firstline of defense against cellulardehydration

Ongoing behavior is notdisrupted by thirst unless thebuffering effects of osmosisand antidiureses areinsufficient

Osmotic homeostasis

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Series of Events in Water Intoxication

Copyright 2009, John Wiley & Sons, Inc.

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27_table_01

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Hormonal Regulation of Na+ and Cl-

Copyright 2009 John Wiley & Sons Inc