For a complete diagram of body fluid compartments, see body fluid compartments of a 70-kg man and body fluid compartments of a 55-kg woman. Note that this diagram places focus only on these three major fluid compartments. Plasma is the smallest fluid compartment (~8% of total body water). Interstitial fluid contains ~25% of the total body water. The intracellular fluid compartment contains most of the water in the body (~67% of total). In fact, intracellular fluid accounts for 60. Intracellular fluids are crucial to the body’s functioning. The most abundant electrolyte in intracellular fluid is potassium. Intracellular fluids (ICF) are found inside cells and are made up of protein, water, electrolytes, and solutes. The right diagram shows the three major fluid compartments drawn to scale. Figure 15.1 Intracellular and Extracellular Compartments. The left diagram allows for a better demonstration of the relationship between the intracellular fluid, interstitial fluid, and plasma, however, the relative size of each of the compartment is not drawn to scale. Waste products produced by cells follow the reverse path from the cytoplasmic compartment to plasma. They then must cross the plasma membrane to enter the cytoplasmic compartment of cells. Nutrient molecules traveling in the blood must first cross the capillary endothelium to enter the interstitial fluid. The capillary endothelium is the physical barrier that separates the interstitial fluid from plasma. A capillary membrane, which consists of the. The physical barrier separating the intracellular fluid compartment (i.e., cytoplasm) and the interstitial fluid is the cell plasma membrane. Fluid movement from the intravascular to interstitial and intracellular compartments occurs in the capillaries. of these cations between the cytosol and the interstitial fluid. Fluid, molecules, and ions flow across physical barriers between the fluid compartments. Thus, Na+ is more concentrated in the extracellular fluids than in the cytosol, and the. These are the (1) intracellular fluid compartment, (2) interstitial fluid, and (3) plasma. To calculate the intracellular fluid volume subtract the extracellular fluid volume from the total fluid volume.In the human body plan, there are three major fluid compartments that are functionally interconnected. To calculate the interstitial (fluid not in the cells and not in the blood) fluid volume, subtract the plasma volume from the extracellular volume. To measure the extracellular fluid volume, use a cell inpermeant marker substance such as inulin or mannitol that will equilibrate everywhere except in the cells (it is possible to make inulin and mannitol radioactive). One such marker is Evan's Blue, a dye which binds to plasma proteins. Therefore, to measure the volume of the blood plasma fluid compartment, you need a marker which equilibrates throughout the blood supply and nowhere else. M U is usually calculated from C U, the concentration of marker lost in the urine and V U, the volume of the urine thus: M U = C U. Where V is the volume of the body fluid compartment, M is the mass of marker injected, M U is the mass of marker lost in the urine during equilibration and C is the measured concentration of the marker. As this is not possible (the kidney will excrete everything dissolved in the bloodstream) the calculation must correct for excretion. To be an absolutely perfect marker, the substance should also not be excreted. Therefore: if you know the mass of marker injected into the body and are able to measure the marker concentration once equilibration is complete, you can calculate the volume of the compartment occupied by the marker. Given that concentration (C) = mass (M) / volume (V) it should be obvious that: Furthermore, it must be possible to measure the concentration of the marker once equilibration is complete.Tritiated ( 3H) water is a good marker for the whole body fluid compartment because it diffuses throughout the body, it is chemically identical to normal water and it is easy to measure the equilibrium concentration because 3H water is radioactive. To be a perfect marker a substance must also not be metabolised. To measure the volume of any fluid compartment within the body you must inject or infuse a marker substance that will equilibrate (diffuse freely to a uniform concentration) throughout this compartment. Body fluid compartments calculations Body Fluid compartments Measuring Body Fluid Compartments
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |