Fluid, Electrolyte & Acid- Base Balance

Body Fluids Your body is 66% water Not evenly distributed – separated into compartments Able to move back and forth thru the cell membranes to maintain an equilibrium

Fluid Compartments Intracellular fluid – fluid inside cells [ICF] Extracellular fluid – fluid outside cells and all other body fluids --- ¼ is plasma [intravascular fluid], remaining ¾ is interstitial fluid. Small amount is localized as CSF, serous fluid, synovial fluid, humors of eye & endo/perilymph of ears

Edema Condition in which fluid accumulates in the interstitial compartment. Sometimes due to blockage of lymphatic vessels or by a lack of plasma proteins or sodium retention

Fluid Balance Amount in = amount out Average daily intake is 2500 ml [ fluids, food and metabolic water] Average daily output is 2500 ml [ urine, feces, perspiration, insensible perspiration] What can throw off these numbers?

Electrolyte Balance Def: - concentration of individual electrolytes in the body fluid compartments is normal and remains relatively constant. Electrolytes are dissolved in body fluids Sodium predominant extracellular cation, and chloride is predominant extracellular anion. Bicarbonate also in extracellular spaces

Electrolyte Balance Potassium is the predominant intracellular cation and phosphates are the predominant intracellular anion Cations are actively reabsorbed, anions passively follow by electrochemical attraction Aldosterone works at kidney tubules to regulate sodium & potassium levels

Electrolyte Balance Because of sodium and potassium influence, water will move between compartments Example: if high [sodium], then water will move from intracellular space to extracellular space due to osmotic pressure

Balance of other Electrolytes Calcium – hypercalcemia / hypocalcemia Magnesium – hypermagnesemia/ hypomagnesemia Phosphate – hyperphosphatemia/ hypophosphatemia Chloride – hyperchloremia/ hypochloremia

Acid - Base Balance Blood - normal pH of 7.2 – = alkalosis 3 buffer systems to maintain normal blood pH 1. Buffers 2. Removal of CO 2 by lungs 3. Removal of H + ions by kidneys

Buffers Protein Buffer Systems  Amino Acid buffers  Hemoglobin buffers  Plasma Protein buffers Phosphate Buffer Systems Carbonic Acid – Bicarbonate Buffer System

Maintenance of Acid-Base Balance Respiratory System: removal of CO 2 by lungs – stabilizes the ECF, has direct effect on Carbonic Acid – Bicarbonate Buffer System Urinary System: removal of H + ions by kidneys

Disturbances to Acid-Base Balance Respiratory Acidosis Respiratory Alkalosis Metabolic Acidosis [ lactic acidosis, ketoacidosis] Metabolic Alkalosis

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