Download presentation
Presentation is loading. Please wait.
Published byDaniel Harrison Modified over 8 years ago
1
Chapter 19 Acid-Base Balance
2
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 2 pH OF BODY FLUIDS Definition of pH—a number that indicates the hydrogen ion (H + ) concentration of a fluid; pH 7.0 indicates neutrality, pH higher than 7.0 indicates alkalinity, and pH less than 7.0 indicates acidity—see Figure 19-1 Normal arterial blood pH—about 7.45 Normal venous blood pH—about 7.35
3
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 3
4
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 4 MECHANISMS THAT CONTROL pH of BODY FLUIDS Buffers Definition—substances that prevent a sharp change in the pH of a fluid when an acid or base is added to it— see Figures 19-2 and 19-3 “Fixed” acids are buffered mainly by sodium bicarbonate (NaHCO 3 ) Changes in blood produced by buffering of “fixed” acids in the tissue capillaries Amount of carbonic acid (H 2 CO 3 ) in blood increases slightly Amount of carbonic acid (H 2 CO 3 ) in blood increases slightly Amount of NaHCO 3 in blood decreases; ratio of amount of NaHCO 3 to the amount of H 2 CO 3 does not normally change; normal ratio is 20:1 Amount of NaHCO 3 in blood decreases; ratio of amount of NaHCO 3 to the amount of H 2 CO 3 does not normally change; normal ratio is 20:1 H + concentration of blood increases slightly H + concentration of blood increases slightly Blood pH decreases slightly below arterial level Blood pH decreases slightly below arterial level
5
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 5
6
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 6
7
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 7 MECHANISMS THAT CONTROL pH of BODY FLUIDS Respiratory mechanism of pH control—respirations remove some CO 2 from blood as blood flows through lung capillaries, the amount of H 2 CO 3 in blood is decreased and thereby its H + concentration is decreased, and this in turn increases blood pH from its venous to its arterial level Urinary mechanism of pH control—being the body’s most effective regulator of blood pH, kidneys usually acidify urine by the distal tubules secreting hydrogen ions and ammonia (NH 3 ) into the urine from blood in exchange for NaHCO 3 being reabsorbed into the blood
8
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 8 pH IMBALANCES Acidosis and alkalosis—pH or acid-base imbalances Disturbances in acid-base balance depend on relative quantities of NaHCO 3 and H 2 CO 3 in the blood Body can regulate both of the components of the NaHCO 3 – H 2 CO 3 buffer system Blood levels of NaHCO 3 regulated by kidneys H2CO 3 levels regulated by lungs Metabolic and respiratory disturbances— pH disturbances —can alter the normal 20:1 ratio of NaHCO 3 to H 2 CO 3 in blood Metabolic disturbances affect the NaHCO 3 levels in blood Respiratory disturbances affect the H 2 CO 3 levels in blood
9
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 9 pH IMBALANCES Metabolic disturbances Metabolic acidosis—bicarbonate (NaHCO 3 ) deficit Metabolic alkalosis—bicarbonate (NaHCO 3 ) excess; complication of severe vomiting Respiratory disturbances Respiratory acidosis (H 2 CO 3 excess) Respiratory alkalosis (H 2 CO 3 deficit) In uncompensated metabolic acidosis, the normal ratio of NaHCO 3 to H 2 CO 3 is changed; in compensated metabolic acidosis, the ratio remains close to 20:1, but the total amount of NaHCO 3 and H 2 CO 3 changes Cardiac arrest and respiratory acidosis
Similar presentations
© 2024 SlidePlayer.com. Inc.
All rights reserved.