Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Ebook BRS Physiology (5th edition). It is new to this edition: Addition of new full-color figures; Updated organization and text; Expanded coverage of cellular,respiratory, renal, gastrointestinal, and endocrine physiology; Increased emphasis on pathophysiology. | Total body water TBW is approximately 60 of body weight. The percentage of TBW is highest in newborns and adult males and lowest in adult females and in adults with a large amount of adipose tissue. A. Distribution of water Figure 5-1 and Table 5-1 1. Intracellular fluid ICF is two-thirds of TBW. The major cations of ICF are K and Mg2 . The major anions of ICF are protein and organic phosphates adenosine triphosphate ATP adenosine diphosphate ADP and adenosine monophosphate AMP . 2. Extracellular fluid ECF is one-third of TBW. is composed of interstitial fluid and plasma. The major cation of ECF is Na . The major anions of ECF are Cl- and HCO3-. a. Plasma is one-fourth of the ECF. Thus it is one-twelfth of TBW 1 4 X 1 3 . The major plasma proteins are albumin and globulins. b. Interstitial fluid is three-fourths of the ECF. Thus it is one-fourth of TBW 3 4 X 1 3 . The composition of interstitial fluid is the same as that of plasma except that it has little protein. Thus interstitial fluid is an ultrafiltrate of plasma. 3. 60-40-20 rule TBW is 60 of body weight. ICF is 40 of body weight. ECF is 20 of body weight. B. Measuring the volumes of the fluid compartments see Table 5-1 1. Dilution method a. A known amount of a substance is given whose volume of distribution is the body fluid compartment of interest. For example 1 Tritiated water is a marker for TBW that distributes wherever water is found. 2 Mannitol is a marker for ECF because it is a large molecule that cannot cross cell membranes and is therefore excluded from the ICF. 144 Chapter 5 Renal and Acid-Base Physiology 145 FIGURE 5-1 Body fluid compartments. 3 Evans blue is a marker for plasma volume because it is a dye that binds to serum albumin and is therefore confined to the plasma compartment. b. The substance is allowed to equilibrate. c. The concentration of the substance is measured in plasma and the volume of distribution is calculated as follows Amount Volume Concentration where Volume volume of .
