body fluid compartments slide share
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BODY FLUID COMPARTMENTS
Dr Anu Priya J
Introduction
• Body is formed of solids & fluids
• The fluid part is more than 2/3 of the whole body.
• Water forms most of the fluid part
40%
15%
20%
5%
Total Body water
Blood volume 7% of body weight5L in a 70 kg adult male
ECF constitutes of:
A. Interstitial fluid including lymph
B. Plasma
C. Transcellular fluids
Transcellular fluids: CSF Intraocular fluid Gastrointestinal secretions Pleural fluid Pericardial fluid Peritoneal fluid Synovial fluid Fluid in urinary tract
More the amount of fat, lesser the ECF volumeElderly – lesser ECF volume Infants & children – greater ECF volume
Body electrolytes
• 7% of total body weight
• Functions of electrolytes in the human body
− Maintenance of acid-base balance
− Maintenance of normal osmolality and volume of body fluids
− Ions like Na+,Ca2+,K+,Cl- , etc affects
excitability of cells
Distribution of ions across the cell membrane at rest
Ion ICF (mmol/L of H20) ECF(mmol/L of H20)
Na+ 1.5 150
K+ 150 5.5
Cl- 9 125
Ca2+ 0.0001 1.2
Protein anion 65 <5
Mg2+ 58 3
HCO3- 10 2.8
PO43- 75 4
Deuterium oxide/heavy water, Tritium oxide, Aminopyrine
Inulin, Mannitol, Sucrose
131I
Applied aspect
Infants are prone to dehydration i.e., infants are more vulnerable for water loss due to:
• Absolute ECF volume is lesser
• Increased body surface area compared to mass
• Higher metabolic rate
• Physiologic inability of the infant’s kidneys to concentrate urine
see http://www.ihrdni.org/068b-022.pdf
Thank you
Measurement of body fluid volumes
• Total body water is measured using dilution principle.
• A marker is injected that will be evenly distributed in all the compartments of body fluids.
• Marker that diffuses freely not only in the water outside the cells, but also crosses the cell membrane to reach the intracellular fluid.
• ECF volume is measured using substances that cannot enter the cells, but can freely cross the capillary membrane and thus distribute evenly in the ECF compartments.
• Plasma volume is measured using substances that binds specifically to plasma proteins, and will not diffuse into the interstitium.
Measurement of body fluid volumes
