1. Fluid and Electrolyte Balance

2. Fluid Balance  relative constancy of body fluid levels  homeostasis Electrolytes  substances such as salts that dissolve or break apart in water solution.

3. Body Fluids  Water is the most abundant body compound  Average body water volume is based on a healthy, nonobese 150lb male  Water is 60% of body weight in males, 50% in females  Volume averages 40L in a 150lb male

4. Body Fluids  Variation in total body water is related to:  the total body weight of the individual,  the fat content of the body- the more fat the less water,  gender – female body has about 10% less water than the male body  age – in a newborn infant, water may account for 80% of total body weight. In the elderly, water per pound of weight decreases.

5. Body Fluid Compartments  Intracellular fluids (ICF)  largest fluid compartment  located inside cells  serves as solvent to facilitate intracellular chemical reactions

6. Body Fluid Compartments  Extracellular fluid (ECF)  Plasma, interstitial fluid (IF), lymph, joint fluids, cerebrospinal fluids, etc..  Called the internal environment of the body  Surrounds cells and transports substances to and from them

7. Mechanisms that Maintain Fluid Balance  As long as output and intake of water are equal, the total amount of water in the body does not change.  Sources of fluid intake – liquids we drink, water in foods, and water formed by catabolism of foods.  Sources of fluid output – kidneys, lungs, skin, and intestines. Of these the kidney’s change the most day to day.

8. Mechanisms that Maintain Fluid Balance  Factors that act as mechanisms for controlling fluid balance 1.Concentration of electrolytes in the ECF 2.Capillary blood pressure 3.Concentration of proteins in the blood

9. The Importance of Electrolytes in Body Fluids  Electrolytes – compounds that break up or dissociate in water solution into separate particles called ions (NaCl)  Ions – the dissociated particles of an electrolyte that carry an electrical charge (Na+)  Nonelectrolytes – organic substances that do not break up or dissociate when placed in water solution (glucose)

10. Electrolyte Functions  Many ions are considered to be major, or important, “trace” elements in the body.  Examples - Iron – hemoglobin production and iodine – thyroid hormone

11. Electrolyte Functions  Electrolytes are required for many cellular activities such as nerve conduction (K+), bone formation and blood clotting (Ca++), and hydrochloric acid production in the stomach (Cl-).

12. Electrolyte Functions  Fluid Volume Variation – “Where sodium goes, water soon follows”  If the concentration of sodium in the blood increases, the volume of blood soon increases.  The kidney’s act as the chief regulator of sodium levels in body fluids

13. Capillary Blood Pressure and Blood Proteins  Capillary blood pressure is a “water pushing” force. It pushes fluid out of the blood in capillaries into the IF.  It decreases blood volume by increasing IF volume  Water continually moves in both directions through the membranous walls of capillaries.  The concentration of proteins in blood plasma is a water pulling or water holding force – pulls water into the blood plasma

14. Fluid Imbalances Dehydration  the fluid imbalance seen most often.  IF volume decreases first, but eventually, if not treated, ICF and plasma volumes also decrease below normal levels.  Caused by too small a fluid intake or too large a fluid output Overhydration  much less common  puts a heavy burden on the heart  usually from giving intravenous fluids too rapidly

15. Diuretics meaning “causing urine”