1. Fluids and Electrolytes Water is the largest single component of the body. Water comprises 95% of the body’s fluids.

2. Water content varies Infant = 70% water Males = 60% water Females = 50% water Elderly = 45% water Muscle = 65% water Fat = 20% water

3. Intake equals Output Intake (2500ml) preformed ingested water (60,30) metabolic water (10) Output (2500ml) urine, feces sweat, evaporation Regulated by aldosterone and ADH

4. Water Compartments Intracellular compartments 2/3 of total water volume Extracellular compartments 1/3 of water volume Movement between regions by filtration and osmosis

5. Electrolytes Acids, Bases and Salts Substances that dissolve in water, conduct electricity and dissociate into ions

6. Acid-Bases Balance pH = - log [H + ] pH = 7.0 is neutral Normal range is 7.35-7.45 Control mechanisms Kidneys Respiratory System Buffers

7. Carbonic Acid/Bicarbonate system major regulator of extracellular pH HCO 3 - functions as weak base H 2 CO 3 functions as weak acid Work by converting a strong acid/base to a weaker one

8. Phosphate Buffer System Similar to that of the bicarbonate system Important urine and intracellular buffer Component parts: NaH 2 PO 4 acts as a weak acid Na 2 HPO 4 acts as a weak base

9. Protein Buffer System Most abundant buffering system in the body including intracellular and extracellular compartments Carboxyl groups (COOH) and amine groups (NH 3 ) act as either an acid or a base

10. Acid - Base Imbalance Acidosis (pH<7.35) Alkalosis (pH>7.45)

11. Respiratory Acidosis or Alkalosis Results from an imbalance of CO 2 Respiratory Acidosis - due to increase of CO 2 decreased respiration results in  CO 2   H +   pH Respiratory Alkalosis - decrease of CO 2 increased respiration or hyperventilation  CO 2   H +  pH CO 2 + H 2 O  H 2 CO 3  H + + HCO 3 -

12. Metabolic Acidosis or Alkalosis Results from imbalance of HCO 3 - Metabolic acidosis - due to decrease of HCO 3,, which lowers pH excessive alcohol, prolonged diarrhea, renal dysfunction Metabolic alkalosis - due to increase of HCO 3, which increases pH excessive vomiting