A+P Chapter 25: Water, Electrolyte and Acid-Base Balance

-Interstitial fluid, plasma, lymph
-High concentrations of Na+, Cl-, and HCO-3 (bicarbonate)
-Plasma contains more protein than other extracellular fluids do

-Fluid within the cell
-Contains high concentrations of K+, phosphate, and magnesium ions

-Intracellular: 37%
-Extracellular: 63%

-Fluid located between the cells; tissue fluid

Extracellular fluid that includes CSF, synovial fluid of joints, glandular secretions, serous fluids in body cavities and the aqueous and vitreous humors in the eyes

-The hypothalamus is the thirst center
-When your body looses water, the hypothalamus is stimulated

-Kidneys eliminate 60% of water, 28% from skin and lungs, 6% in feces and 6% in sweat
-Kidneys are the primary regulator of water output through the action of ADH and aldosterone
-When the body water content is high, the secretion of ADH decreases

-Capillary filtration force
-Plasma oncotic pressure
-Lymphatic drainage
-Plasma proteins
-Alteration of any of these factors affect water movement

-The kidneys control the composition of body fluids by regulating the renal excretion of electrolytes

-The chemical reaction caused when an electrolyte splits into two ions

-136-145 mEq/L
-Chief extracellular cation, regulates extracellular volume, nerve-muscle function
-Aldosterone stimulates the distal tubule of nephron to reabsorb Na+
-Where sodium moves, water moves

-Excess Na+ in blood and is the result of excess water loss or increased Na+
-Elderly pts. following surgery or fever
-Pts. who have been on prolonged diuretic therapy
-Uncontrolled diabetic pts. (polyuria)

-Decrease in the concentration of plasma Na+
-Pts. with heart failure has expanded blood volume

-3.5-5.0
-Chief intracellular cation, participates in nerve muscle function
-Aldosterone stimulates the kidney to excrete K+ in the urine

-Excess K+ in the blood
-Primary cause is kidney disease
-Treated with dialysis (to remove K+) or IV administration of insulin-glucose solution (drives glucose and K+ into the cells, lowering plasma levels)

-Lower that normal amount of K+ in the blood
-Usually presents as leg cramp, muscle fatigue, abdominal distention and cardiac rhythm disturbances
-Most common cause is prolonged use of potassium loosing diuretics
-Treated by administration of K+

-4.5-5.8 mEq/L
-Strengthen bone and teeth, participates in muscle contraction, helps in blood clotting
-Parathyroid hormone is the primary regulator of plasma levels of Ca2+

-1.5-2.5 mEq/L
-Strengthens bones, participates in nerve muscle function

-95-108 mEq/L
-Chief extracellular anion, involved in extracellular volume control

-22-26 mEq/L
-Part of bicarbonate buffer system, participates in acid-base balance

-2.5-4.5 mEq/L
-Strengthens bone, participates in acid-base balance

-A substance that dissociates (splits) into H+ and and anion like
-HCl-->H+ + Cl-

-A substance that combines with H+ during a chemical reaction and removes H+ form solution
-OH- + H+-->H2O

-A unit of measurement that indicates the number of H+ in a solution
-As the number of H+ increase the pH decreases
-As the number of H= decreases the pH increases

-Acidosis: a plasma level of less than 7.35
-Alkadosis: a plasma pH more than 7.45

-Most H+ comes from the bodes chemical reactions during metabolism
-ie: glucose (with O2) is metabolized into carbonic acid and energy
-ie: glucose (w/o O2) is metabolized into lactic acid
-ie: when fatty acids are metabolized they yield ketoacids
-ie: some proteins yield sulfuric acid when metabolized

-pH buffers
-Lungs
-Kidney function

-A chemical substance that prevents large changes in pH
-Consists of a buffer pair (1 giver+1 taker); the "taker" part of the buffer removes H+ from the blood, the "giver" donates H+ to the blood
-Most important buffers are bicarbonate, phosphate, hemoglobin, and plasma buffers

-CO2 can combine with water to form an acid(H+)
-By decreasing respiratory rate, the body retains CO2, which increases H+ and decreases pH
-Basis for respiratory acidosis
-The medulla oblongata (the respiratory center in the brain) senses changes in H+ concentration and is stimulated to increase or decrease respirations

-The kidneys regulate pH bu reabsorbing or excreting H+ as needed
-Kidneys also excrete or absorb bicarbonate (a major buffer)
-Pts with kidney failure are generally acidotic

-Decrease in plasma pH below 7.35
-2 types: respiratory and metabolic

-Caused by any condition that decreases the effectiveness of the respiratory system: i.e. chronic lung disease, high doses of narcotics, injury to the medulla oblongata
-Hypoventilation, increases plasma levels of CO2 which forms H+ and decreases pH and causes acidosis

-First, the buffer system removes some of the excess H+
-Second, the kidneys excrete excess H+

-Decrease in plasma pH due to non respiratory conditions ie: kidney disease, uncontrolled diabetes mellitus, prolonged vomiting, severe diarrhea

-First the buffer system removes some of the excess H+
-Second, the respiratory system helps remove H+ through hyperventilation or Kussmaul respirations

-An increase in plasma pH above 7.45
-Respiratory and metabolic

-Caused from hyperventilation and decrease in plasma CO2
-The body tries to correct by first, the buffers donate H+ to the plasma, thereby decreasing pH and second, the kidneys decrease the excretion of H+

-An increase in pH caused by non respiratory disorders i.e. overuse of antacids and bicarbonate containing drugs, persistent vomiting, frequent NG suctioning
-The body tries to correct by first, the buffers donate H+, then the kidneys decrease their excretion of H+, and finally the lungs decreases respiratory rate