BIC111 - Lab Session 4.pdf

9/23/2024 Body Buffers Systems Arterial Blood Gas Basics Lab Session 4...

9/23/2024 Body Buffers Systems Arterial Blood Gas Basics Lab Session 4 Amine BAHI, PhD September 24, 2024 1 Main Objectives Define buffer systems and explain their role in maintaining acid-base balance Identify the major buffer systems in the human body, including the bicarbonate, phosphate, and protein buffer systems Describe how buffer systems resist changes in pH by neutralizing excess acids or bases, and explain the chemical mechanisms behind this process Explain the role of the bicarbonate buffer system in maintaining blood pH, and how it interacts with the respiratory and renal systems to regulate acid-base balance Analyze the clinical importance of buffer systems in preventing conditions like acidosis and alkalosis BIC111 – Lab Session 4 2 2 1  9/23/2024 Arterial Blood Gas ‘ABG’ Basics − Overview An analysis of arterial blood gases “ABG” can tell you a lot about what is going on inside a patient Homeostatic mechanisms in the body try very hard to keep pH, PaO2 and PaCO2 at constant, physiological levels The lungs and the kidney work collaboratively to ensure that this is the case in the short and long term, respectively When pH, gases and bicarbonate ions (HCO3-) diverge from their usual ranges, the pattern of changes hint at what is wrong, and what the body is trying to do about it BIC111 – Lab Session 4 3 3 Arterial Blood Gas ‘ABG’ Basics − Overview An ABG test measures the oxygen and carbon dioxide levels in your blood as well your blood's pH balance The sample is taken from an artery, not a vein, and healthcare providers typically order it in certain emergency situations BIC111 – Lab Session 4 4 4 2  9/23/2024 Few Definitions Acids − substances capable of losing H ions Bases − substances capable of accepting H ions pH − represent the free hydrogen ions’ concentration Buffer − substance that reacts with acids & bases to maintain neutral environment “stable pH” BIC111 – Lab Session 4 5 5 Buffers A buffer solution is a solution that resists significant changes in its pH when small amounts of an acid or base are added The buffer works by neutralizing any added acids (H⁺ ions) or bases (OH⁻ ions) Maintain a relatively stable pH, making it essential in biological systems BIC111 – Lab Session 4 6 6 3  9/23/2024 Acid-Base Balance in the Body Equilibrium between the acid and base elements of the blood and body fluids Normal ration of carbonic acid (H2CO3) to bicarbonate (HCO3-) is 1:20 If this ratio is maintained, the pH remains within the normal range of 7.35 - 7.45 BIC111 – Lab Session 4 7 7 Acid-Base Imbalance in the Body Acidosis − pH  7.35 and occurs when: Acids (hydrogen ions) accumulate; or Bases (HCO3-) are lost Alkalosis − pH  7.35 and occurs when: Bases (HCO3-) accumulate; or Acids (hydrogen ions) are lost BIC111 – Lab Session 4 8 8 4  9/23/2024 Chemical Buffer System BIC111 – Lab Session 4 9 9 Physiological Buffer System BIC111 – Lab Session 4 10 10 5  9/23/2024 Regulation of Acid-Base Balance BIC111 – Lab Session 4 11 11 Acidemia or Alkalemia Regulation of blood pH is a business that is run collaboratively by the lungs & the kidneys. They have quite distinct roles (see later) It all comes down to the equation central to CO2 transport in blood The reaction could occur in either direction depending on the amounts of the reaction components present BIC111 – Lab Session 4 12 12 6  9/23/2024 Bicarbonate Buffer System The body’s primary buffer system: Lungs regulate production of carbonic acid (H2CO3) through CO2 Kidneys regulate production of bicarbonate (HCO3-) BIC111 – Lab Session 4 13 13 Bicarbonate Buffer System Lungs control CO2 content in the ECF by adjusting ventilations (response within  15 min) In elevated CO2 levels, lungs increase respiratory rate (fast breathing) Hyperventilation to eliminate excess CO2 leading to pH increase In reduced CO2 levels, lungs decrease respiratory rate (slow breathing) Hypoventilation to retain CO2 leading to pH decrease BIC111 – Lab Session 4 14 14 7  9/23/2024 Bicarbonate Buffer System Kidneys regulate bicarbonate in the ECF by reabsorbing acids and bases or excreting them into the urine In acidosis, kidneys excrete H+ and conserve HCO3- ions to restore balance In alkalosis, kidneys retain H+ & excrete HCO3- ions to restore balance Very slow response − within hours to days It’s the most effective buffering systems BIC111 – Lab Session 4 15 15 Bicarbonate Buffer System BIC111 – Lab Session 4 16 16 8  9/23/2024 Phosphate Buffer System Important in ICF and urine pH regulation Two phosphate ions: mono & dihydrogen phosphate (HPO₄²⁻/H₂PO₄⁻) The excess of acid is neutralized by reacting with monohydrogen phosphate to form dihydrogen phosphate HPO42- + H3O+ → H2PO4- + H2O The excess of base is neutralized by dihydrogen phosphate to form monohydrogen phosphate H2PO4- + OH- → HPO42- + H2O BIC111 – Lab Session 4 17 17 Protein Buffer System Help regulate pH in ECF and ICF Protein buffering is a description of the process wherein protein compounds “consume” small amounts of acids or bases Consists of plasma proteins (albumin, hemoglobin) For example, hemoglobin is a protein that binds to small amounts of acids in the blood, removing the acid before it changes the blood's pH BIC111 – Lab Session 4 18 18 9  9/23/2024 Protein Buffer System Proteins are just chains of amino acids. The later are compounds composed of amine (– NH2) & carboxylic acid (–COOH) functional groups, linked to the same carbon atom Excess of acid is neutralized by the exposed amine group (NH2) accepting H+ ions BIC111 – Lab Session 4 19 19 Protein Buffer System Proteins are just chains of amino acids. The later are compounds composed of amine (– NH2) & carboxylic acid (–COOH) functional groups, linked to the same carbon atom Excess of base is neutralized by the exposed carboxy group (COOH) releasing H+ ions BIC111 – Lab Session 4 20 20 10  9/23/2024 Acid-Base disorders in the Body BIC111 – Lab Session 4 21 21 Acid-Base disorders in the Body BIC111 – Lab Session 4 22 22 11  9/23/2024 Respiratory Acidosis − Overview A condition that occurs when the lungs can’t remove enough CO2 from the body This leads to a CO2 accumulation in the blood, which causes and acidic blood (low pH) BIC111 – Lab Session 4 23 23 Respiratory Acidosis − Causes Respiratory acidosis can be caused mainly by depression of respiratory center (Hypoventilation) Chronic obstructive pulmonary disease (COPD) Narcotics / over sedation, anesthesia Respiratory arrest Paralysis of respiratory muscles, asthma Impaired ventilation Airway obstruction (foreign body)… BIC111 – Lab Session 4 24 24 12  9/23/2024 Respiratory Acidosis − Symptoms Respiratory acidosis signs & symptoms include: Decrease excitability of CNS Headache, drowsiness, disorientation, coma … CVS − dysrhythmias, decreased cardiac contractility, hypotension … Hypercalcemia − acidosis decreases binding of Ca to albumin Increase serum ionized Ca++ levels BIC111 – Lab Session 4 25 25 Respiratory Acidosis − Compensation BIC111 – Lab Session 4 26 26 13  9/23/2024 Metabolic Acidosis − Overview A condition mainly due to loss of bicarbonate  pH decrease in the blood Main causes: increased/excess acid generation, prolonged severe diarrhea, diminished renal acid excretion, renal failure … BIC111 – Lab Session 4 27 27 Metabolic Acidosis − Compensation BIC111 – Lab Session 4 28 28 14  9/23/2024 Respiratory Alkalosis − Overview A condition mainly due to a decrease in CO2 levels due to increased excretion by the lungs pH increase in the blood Main causes: Hyperventilation, Hypoxemia, Fever, Anger… Psychological dyspnea − extreme anxiety-induced hyperventilation, experiencing shortness of breath BIC111 – Lab Session 4 29 29 Respiratory Alkalosis − Symptoms Respiratory alkalosis can be caused mainly by activation of respiratory center (Hyperventilation) Increase excitability of CNS Light headedness, numbness, tingling, confusion, blurred vision, inability to concentrate … CVS − increased cardiac contractility, hypertension … Hypokalemia − increased blood pH cause a shift of K out of the plasma & interstitial fluids into the urine BIC111 – Lab Session 4 30 30 15  9/23/2024 Respiratory Alkalosis − Compensation - BIC111 – Lab Session 4 31 31 Metabolic Alkalosis − Overview A condition mainly due to an accumulation of bicarbonate in the body pH increase in the blood The most common cause of metabolic alkalosis is a loss of stomach acid, caused by excessive vomiting BIC111 – Lab Session 4 32 32 16  9/23/2024 Metabolic Alkalosis − Compensation BIC111 – Lab Session 4 33 33 Click to edit Master title style 9/23/2024 9/23/2024 34 17