1. Blood buffering system

2. The pH of Body fluids • The pH of blood is 7.35 – 7.45 • Changes in pH below 6.8 and above 8.0 may result in death.

4. The pH of body fluids is maintained by three major buffer systems: 1- Carbonic acid–bicarbonate system. 2- Dihydrogen phosphate – hydrogen phosphate system. 3- The ability of proteins to act as either proton acceptors or proton donors at different pH values. • The carbonic acid–bicarbonate system is the principal buffer in blood serum and other extracellular fluids. • The hydrogen phosphate system is the major buffer within cells.

6. Proteins as a blood buffer • Proteins contain – COO- groups, which, like acetate ions (CH3COO-), can act as proton acceptors. • Proteins also contain – NH3+ groups, which, like ammonium ions (NH4+), can donate protons.

7. Respiratory and Renal regulation • Both the respiratory & renal systems work to regulate pH in acid-base imbalance; the respiratory system works in a matter of minutes & is maximal within 12-24 hours while the renal (kidneys) system continues to function for days to restore pH within normal limits (WNL).

8. Respiratory Regulation ofAcid-Base Balance • Respiratory regulation of pH is achieved through carbonic acid/bicarbonate buffer system • As carbon dioxide levels increase, pH decreases • As carbon dioxide levels decrease, pH increases • Carbon dioxide levels and pH affect respiratory centers • Hypoventilation increases blood carbon dioxide levels • Hyperventilation decreases blood carbon dioxide levels

9. Respiratory Regulation ofAcid-Base Balance

10. Renal Regulation of Acid-Base Balance • Secretion of H+ into filtrate and reabsorption of HCO3- into ECF cause extracellular pH to increase • HCO3- in filtrate reabsorbed • Rate of H+ secretion increases as body fluid pH decreases .

11. Acidosis and Alkalosis • Acidosis: pH body fluids below 7.35 • Respiratory: Caused by inadequate ventilation • Metabolic: Results from all conditions other than respiratory that decrease pH • Alkalosis: pH body fluids above 7.45 • Respiratory: Caused by hyperventilation • Metabolic: Results from all conditions other than respiratory that increase pH

12. Respiratory Acidosis: CO2 ↑ pH ↓ • Symptoms: Failure to ventilate, suppression of breathing, disorientation, weakness, coma • Causes: Lung disease blocking gas diffusion, depression of respiratory center by drugs, cardiopulmonary arrest, stroke, or nervous system disorders • Treatment: Correction of disorder, infusion of bicarbonate

13. Respiratory Alkalosis: CO2 ↓ pH ↑ • Symptoms: Increased rate and depth of breathing, numbness, light-headedness, tetany • Causes: hyperventilation due to anxiety, hysteria, fever, exercise; reaction to drugs such as salicylate, quinine, and antihistamines • Treatment: Elimination of anxiety producing state, rebreathing into a paper bag

14. Metabolic (Nonrespiratory) Acidosis:H+ ↑ pH ↓ • Symptoms: Increased ventilation, fatigue, confusion • Causes: Renal disease, hepatitis and cirrhosis; increased acid production in diabetes mellitus, hyperthyroidism, starvation; loss of alkali in diarrhea; acid retention in renal failure • Treatment: Sodium bicarbonate given orally, dialysis for renal failure, insulin treatment for diabetic ketosis

15. Metabolic (Nonrespiratory) Alkalosis:H+ ↓ pH ↑ • Symptoms: Depressed breathing, confusion • Causes: Vomiting, diseases of the adrenal glands, ingestions of access alkali • Treatment: Infusion of saline solution, treatment of underlying diseases