Unit Five: The Body Fluids and Kidneys 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 Daily intake of water Daily loss of water-insensible water loss Fluid loss in sweat Water loss in feces Water loss by the kidneys

Prolonged Heavy Exercise Table 25.1 Daily Intake and Output of Water (ml/day) Normal Prolonged Heavy Exercise Intake Fluids ingested 2100 ? From metabolism 200 Total Intake 2300 Output Insensible-skin 350 Insensible-lungs 650 Sweat 100 5000 Feces Urine 1400 500 Total Output 6600

Body Fluid Compartments Fig. 25.1 Summary of body fluid regulation, including the major body fluid compartments

Compartments (cont.) Body Fluid Compartments Intracellular Extracellular-interstitial fluid and blood plasma Transcellular-fluids in the synovial, peritoneal, pericardial, intraocular spaces, and the CSF 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 Constitutes about 40% of the fluid in the average person Concentration of substances is similar from cell to cell

Compartments (cont.) Extracellular Fluid Compartment Interstitial fluid-makes up about 75% of the fluid Blood plasma-makes up 25% of the fluid Only real difference between the two types is the protein composition of the plasma

Blood Volume Blood Volume Makes up about 7% of the body weight (5 L) 60% plasma and 40% cells Percentages vary according to gender, weight, etc. Hematocrit Red blood cell fraction of the blood 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 Magnesium 0.8 0.7 20 Chlorine 108 4 Bicarbonate 24 28.3 10 Phosphate 2 11 Sulfate 0.5 1 Phosphocreatine 45 Carnosine Amino acids 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 9 Lactate 1.2 1.5 ATP 5 Hexose monophosphate 3.7 Glucose 5.6 Protein 4 Urea Others 4.8 3.9 10 Total mOsm/L 301.8 300.8 301.2 Corrected osmolar activity 282 281 Total Osmotic Pressure (37 C) 5443 5423

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 intra- cellular 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 Hyponatremia Depression of metabolic systems of tissues Lack of adequate nutrition to the cells Extracellular Edema Abnormal leakage of fluid from plasma Failure of the lymphatics to return the fluid (lymphedema)