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Chapter 25: The Body Compartments: Extracellular and Intracellular Fluids; Edema Guyton and Hall, Textbook of Medical Physiology, 12th edition Balance of Fluid Intake and Output • Steady-State Balance a. b. c. d. e. Daily intake of water Daily loss of water-insensible water loss Fluid loss in sweat Water loss in feces Water loss by the kidneys Table 25.1 Daily Intake and Output of Water (ml/day) Normal Prolonged Heavy Exercise Fluids ingested 2100 ? From metabolism 200 200 Total Intake 2300 ? Insensible-skin 350 350 Insensible-lungs 350 650 Sweat 100 5000 Feces 100 100 Urine 1400 500 Total Output 2300 6600 Intake Output Body Fluid Compartments Fig. 25.1 Summary of body fluid regulation, including the major body fluid compartments Compartments (cont.) • Body Fluid Compartments a. Intracellular b. Extracellular-interstitial fluid and blood plasma c. Transcellular-fluids in the synovial, peritoneal, pericardial, intraocular spaces, and the CSF d. Total body water for men is about 60% and 50% for women e. Varies with age, gender, and degree of obesity Compartments (cont.) • Intracellular Fluid Compartment a. Constitutes about 40% of the fluid in the average person b. Concentration of substances is similar from cell to cell Compartments (cont.) • Extracellular Fluid Compartment a. Interstitial fluid-makes up about 75% of the fluid b. Blood plasma-makes up 25% of the fluid c. Only real difference between the two types is the protein composition of the plasma Blood Volume • Blood Volume a. Makes up about 7% of the body weight (5 L) b. 60% plasma and 40% cells c. Percentages vary according to gender, weight, etc. • Hematocrit a. Red blood cell fraction of the blood b. 96% accurate because you cannot pack the cells completely c. Males (o.40) and females (o.30) Constituents of Extra- and Intracellular Fluids Fig. 25.2 Major cations and anions of intracellular and extracellular fluids. Fig. 25.2 Nonelectrolytes of the plasma Constituents of Extra- and Intracellular Fluids Table 25.2 Osmolar substances in extracellular and intracellular fluids Plasma (mOsm/L of Water Interstitial (mOsm/L of Water Intracellular (mOsm/L of Water Sodium 142 139 14 Potassium 4.2 4.0 140 Calcium 1.3 1.2 0 Magnesium 0.8 0.7 20 Chlorine 108 108 4 Bicarbonate 24 28.3 10 Phosphate 2 2 11 0.5 0.5 1 Sulfate Phosphocreatine 45 Carnosine 14 Amino acids 2 2 8 Constituents of Extra- and Intracellular Fluids Table 25.2 Osmolar substances in extracellular and intracellular fluids Plasma (mOsm/L of Water Interstitial (mOsm/L of Water Intracellular (mOsm/L of Water Creatine 0.2 0.2 9 Lactate 1.2 1.2 1.5 ATP 5 Hexose monophosphate 3.7 Glucose 5.6 5.6 Protein 1.2 0.2 4 Urea 4 4 4 4.8 3.9 10 301.8 300.8 301.2 Corrected osmolar activity 282 281 281 Total Osmotic Pressure (37 C) 5443 5423 5423 Others Total mOsm/L Basic Principles of Osmosis and Osmotic Pressure • Osmosis is the net diffusion of water across a selectively permeable membrane from a region of high water concentration to one that has a lower water concentration. • Rate of diffusion of water is called the rate of osmosis. Moles vs. Osmoles • Osmoles-the total number of particles in a solution • One osmole is equal to 1 mole of solute particles • Osmole refers to the number of osmotically active particles in a solution rather than to the molar concentration Osmolality vs. Osmolarity • Osmolality = osmoles/kg of water • Osmolarity = osmoles/L of solution Osmotic Equilibrium • Isotonic-occurs if the water concentration of both intracellular and extracellular fluid is the same; cells do shrink or swell • Hypotonic-occurs if the water concentration is lower inside the cell (solutes are higher inside) and the cell will swell and possibly lyse • Hypertonic-occurs if the water concentration is higher inside the cell (solutes are lower inside) and the cell shrivels (crenates); water flows out of the cell Fig. 25.5 Effects of isotonic, hypotonic, and hypertonic solutions on cell volume Equilibrium (cont.) • Isosmotic-solutions with an osmolarity the same as the cell • Hyperosmotic-solutions with a higher osmolarity • Hyposmotic-solutions with a lower osmolarity Volume and Osmolality in Abnormal States • Effect of adding saline to extracellular fluid • Hyponatremia • Hyperantremia Edema • Intracellular Edema a. Hyponatremia b. Depression of metabolic systems of tissues c. Lack of adequate nutrition to the cells • Extracellular Edema a. Abnormal leakage of fluid from plasma b. Failure of the lymphatics to return the fluid (lymphedema)