Buffer System PDF

Buffer Systems Acid Base disorders Dr. Mohamed Bakr  What is pH  p stands for “potenz”, a German word for power or potency  H stands for Hydrogen  Discovered by a Danish Chemist named Soren Peder Lauritz Sorensen in 1909 who was studying the effects of ion concentrati...

Buffer Systems Acid Base disorders Dr. Mohamed Bakr  What is pH  p stands for “potenz”, a German word for power or potency  H stands for Hydrogen  Discovered by a Danish Chemist named Soren Peder Lauritz Sorensen in 1909 who was studying the effects of ion concentrations on proteins  pH is a simple way of expressing this concentration  pH 1 10 Neutral ACID Alkali  pH  We are measuring the concentration of H+  A high concentration of H+ will result in a lower pH  A low concentration of H+ will result in a higher pH  Acids  Acids are substances that contain and can therefore release hydrogen ions H+ H+ H+  Hydrochloric acid (HCI)  Carbonic Acid (H2C03)  Lactic Acid (C6H603)  Bases  Substances that are able to combine with H+ ions HC03- HC03- (essentially antacids) HC03-  The chemical opposite of an acid  Bicarbonate (HC03-)  In the Body  Proteins within the body rely on a narrow pH range 1 7.35 - 7.45 10  Outside of this range proteins begin to lose their structure and function  Balanced H+ H+ H+ 7.40 HC03-HC03- HC03- Acidaemia PH Alkalaemia 7.45  BUFFER  Buffer is a mixture of weak acid and salt of conjugate base that resist the change in pH upon the addition of acid or base. BUFFER + H+ H+ BUFFER IMPORTANCE OF BIOLOGICAL BUFFER  To maintain homeostatic.  To regulates enzymatic function.  To control pH in biochemical reaction. TYPES OF BIOLOGICAL BUFFER  Bicarbonate Buffer  Phosphate Buffer  Protein Buffer  Hemoglobin BICARBONATE BUFFER SYSTEM weak acid H2CO3 bicarbonate salt NaHCO3 CO2 + H2O H2CO3 H + + HCO3 - Transport of co2 between RBC &plasma  PHOSPHATE BUFFER  The Main Elements Of The Phosphate Buffer System Are H2PO4 -1 AND HPO42- HCl +Na2HPO4 NaH2PO4 +NaCl NaOH+NaH2PO4 Na2HPO4 + H2O  PHOSPHATE BUFFER  The Main Elements Of The Phosphate Buffer System Are H2PO4 -1 AND HPO42- HCl +Na2HPO4 NaH2PO4 +NaCl NaOH+NaH2PO4 Na2HPO4 + H2O PHOSPHATE BUFFER IS IMPORTANT IN TUBULAR FLUIDS BY KIDNEY FOR TWO REASON- 1.concentration of phosphate is more in tubules 2. tubular fluid has low pH PROTEIN BUFFER SYSTEM Protein are made up of amino acids. amino acid have a central carbon atom with four groups of it: 1.Carboxyl Group (COOH) 2.Amino Group (NH2) 3.Hydrogen Atom 4.R Group -the carboxyl and amino groups act as buffer system for acidic and basic condition -at neutral pH the carboxyl ion is present as COO- instead of COOH -acidic medium becomes COOH -basic medium become COO- At neutral pH the amino group is NH3+ rather than just NH2 -acidic medium becomes NH3+ -basic medium becomes NH2 HAEMOGLOBIN BUFFER -Histidine in hemoglobin molecule contain imidazole, which contains two groups: Fe group concerned with carriage of oxygen &imidazole nitrogen group is responsible for buffering property of hemoglobin. -Responsible for buffering most of co2 added to blood by tissues. Histidine  RESPIRATORY REGULATION co2 is formed in body by metabolic processes then diffuses from cell into blood transport to lungs into alveoli transported to atmosphere by pulmonary ventilation. RENAL MECHANISM OF ACID BASE REGULATION kidney regulate the blood PH by a)Absorption of filtered b)manufacture of H + -formation of titrable acid Na2HPO4 Na+ + Na+ +HPO4- + H+ NaH2PO4 (EXCRETED) + Na+ (reabsorbed as NaHCO3) DISORDER OF ACID BASE REGULATION Respiratory Acidosis Respiratory Alkalosis Metabolic Acidosis Metabolic Alkalosis  Blood Gas Values  pH 7.35 – 7.45  Pa02 10 – 13.5  PC02 4.5 – 6.0  BE -2 - +2  ST Bicarb 22 - 26 What is Acidosis and Alkalosis?  Acidaemia HC03- HC03- H+ H+ H+ 7.45 Respiratory Regulation  Respiratory Regulation  Respiration is controlled by the Medulla in the brain  Central Chemo-receptors pick up changes in the concentration of CO2 and H+ in the blood  High CO2 or H+ will produce deeper more rapid breathing  Low CO2 or H+ will produce slower more shallow breathing  WHY?  Metabolic Regulation  Cells in the distal tubules sense pH change  The kidneys secrete H+  Reabsorb Bicarbonate ions  Make new Bicarbonate  5-step approach (Resuscitation Council) 1. How is the patient 2. What is the Ph 3. Is the patient hypoxaemic 4. What is the respiratory component 5. What is the metabolic component Respiratory v Metabolic Imbalance Respiratory pC02 Metabolic HC03-/H+  Lungs can only breath  HC03- can be used up fast or slow slowly or quickly  Changes in pC02 are  H+ can be produced slowly or quickly instant  Reabsorbing or replacing HC03- takes days  Metabolic Imbalance  Metabolic Acidosis  Metabolic Alkalosis HC03- HC03- pC02 pC02 Treatment for Metabolic Acidosis  Treat Cause  Hyperglycaemia give insulin  Dehydration give fluids  Renal Impairment give renal replacement therapy  Shock support blood pressure  Surgery for ischaemic bowel  Metabolic Acidosis Metabolic Alkalosis  Lactic Acidosis  Vomiting  Hyperglycaemia  Anorexia  Starvation Diet  Excessive diuretics  Acute Cardiac Failure  Excessive ingestion of  Ischaemic Bowel antacids  Shock Treatment for Metabolic Alkalosis  Vomiting give anti-emetics  Avoid Diuretics  Stop ingestion of antacids  Acute Respiratory Imbalance  Respiratory Acidosis  Respiratory Alkalosis pC02 pC02 HC03- HC03-  Longer Term/Chronic Respiratory Imbalance  Respiratory Acidosis  Respiratory Alkalosis pC02 pC02 HC03- HC03-  Respiratory Acidosis Respiratory Alkalosis Hypoventilation due to Hyperventilation due to  Respiratory Disease  Anxiety  CNS depression  Pyrexia  Circulatory Failure  Pain  Neuromuscular disorders  Over ventilation  Reduced lung  Hypoxia capacity/thoracic injuries  Aspirin overdose Treatment of Respiratory Acidosis  Check airway and ensure patent  Ventilate to increase rate and tidal volume  Non-invasive ventilation  Avoid Opiates  Bronchodilators  Drain effusions  Treat infections Treatment of Respiratory Alkalosis  Reduce ventilation  Paper bag re-breath CO2  Treat pain and fever  Check for overdose and consider active charcoal/RRT/IV fluids  Coach patient to reduce anxiety