Physiology Practical 1 PDF

Physiology Calculation of the Volumes of Body Fluids practical (1) DR. El-Sawy 0  Physiology Calculatio...

Physiology Calculation of the Volumes of Body Fluids practical (1) DR. El-Sawy 0  Physiology Calculation of the Volumes of Body Fluids 65% Of adult body 75% Of infant body Water content (total body Infants have up to 75% body weight water/TBW) as water which is why severe (40-42 L) in an adult weighing 70 Kg diarrhea can be life-threatening The percentage varies between 50-70% depending on gender and amount of adipose tissue Males tend to have a higher percentage of water than females. Water content is inversely correlated with adipose tissue. Simple tool is the 60-40-20 Body fluid compartments DR. El-Sawy 1  Physiology Calculation of the Volumes of Body Fluids ICF and ECF are different in ionic composition : Cation Anion Intracellular  K  PO4 + 3- fluid  Mg2+ Extracellular  Na  Cl + fluid  HCO3 Principle of measurement  A known amount of a dye or indicator is injected into the body.  Then the dye concentration in that compartment is measured.  The compartment volume is calculated as follow: Amount of dye injected Volume of fluid = Concentration of dye DR. El-Sawy 2  Physiology Calculation of the Volumes of Body Fluids Characters of dye Measurement of total body water (TBW):  Deuterium oxide (D2O, heavy water) (most frequently used). Indicators  Tritium oxide  Aminopyrine. Character  They are distributed ICF and ECF.  Amount of D2O injected = 4 mg  Plasma concentration = 0.01 mg/100 ml Problem 4mg 𝑽𝒐𝒍𝒖𝒎𝒆 = =𝟒𝟎𝑳𝒊𝒕𝒆𝒓𝒔 0.01x10 Measurement of ECF volume:  Inulin (more accurate) Indicators  Mannitol  Sucrose. Character  Distributed only in ECF. Measurement of intracellular fluid volume:  ICF = TBW- ECF volume. DR. El-Sawy 3  Physiology Calculation of the Volumes of Body Fluids Measurement of plasma volume: 1. Evans blue dye (more common) Indicators 2. Radioactive iodine bound to plasma protein. Character  They are distributed only in vascular part of ECF Measurement of ISF  ISF= ECF -plasma volume Measurement of blood volume 𝑝𝑙𝑎𝑠𝑚𝑎 𝑣𝑜𝑙𝑢𝑚𝑒 Blood Volume = 1−H𝑒𝑚𝑎𝑡𝑜𝑐𝑟𝑖𝑡 Measurement of RBCs volume  Can be measured directly by: 1. chromium (Cr51) 2. Iron (Fe 59) 3. Phosphorus (P32) RBCs volume = Blood volume – Plasma volume DR. El-Sawy 4  Physiology Calculation of the Volumes of Body Fluids Increase water loss Or Decrease water loss Or Decrease water intake Increase water intake ↓ ↓ Overhydration Dehydration or edema DR. El-Sawy 5  Physiology Calculation of the Volumes of Body Fluids  A 70 kg male is injected with 1.5 g of mannitol.  During the equilibration period, 5% of the mannitol was excreted/hour  After two hours of equilibration, the plasma concentration of mannitol was measured as 9 mg/100 ml.  What body fluid compartment is being measured, and what is its volume? Is this a reasonable number?  A 70 kg male is injected with 1.5 g of mannitol and 4 mg of deuterium oxide  After two hours of equilibration, the plasma concentration of mannitol was 9 mg/100 ml and for deuterium oxide was 0.01 mg/dl  What is the volume of ISF?  In a 70 kg male, Calculate the average volume of TBW, ICF, ECF  An adult female is injected with 500 mg of Evans blue dye.  After equilibration, the plasma concentration of Evans blue was 16 mg/100 ml.  Her hematocrit was 35%  What is the volume of the blood? DR. El-Sawy 6