Regulation of Bicarbonate/Carbonic Acid Buffer System
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Questions and Answers

What is the main goal of the regulation of the bicarbonate/carbonic acid system?

  • Maintain a ratio of 30 Bicarbonate: 1 Carbonic Acid
  • Maintain a ratio of 10 Bicarbonate: 1 Carbonic Acid
  • Maintain a ratio of 20 Bicarbonate: 1 Carbonic Acid (correct)
  • Maintain a ratio of 40 Bicarbonate: 1 Carbonic Acid
  • Which organ is responsible for regulating the metabolic component (HCO-3) in the bicarbonate/carbonic acid system?

  • Lungs
  • Kidneys (correct)
  • Liver
  • Heart
  • What is the duration of respiratory compensation?

  • Longer than 24 hours
  • Less than 24 hours
  • 24 hours (correct)
  • 24-48 hours
  • What is the effect of H2CO3 reduction on kidney function?

    <p>Kidneys decrease HCO-3 to maintain pH 7.4</p> Signup and view all the answers

    What is the term for a decrease in HCO-3 levels in the blood?

    <p>Metabolic acidosis</p> Signup and view all the answers

    How many types of acid-base disturbances are there?

    <p>4</p> Signup and view all the answers

    What is the primary function of buffer systems in the body?

    <p>To maintain a constant pH by neutralizing effects of hydrogen ions</p> Signup and view all the answers

    What is the measure of the concentration of hydrogen ions in an aqueous solution?

    <p>pH</p> Signup and view all the answers

    How many moles of H+ are yielded by reactions in the body per day?

    <p>15-20 mol</p> Signup and view all the answers

    What is the term for the state of internal balance to maintain physical and chemical conditions by living systems?

    <p>Homeostasis</p> Signup and view all the answers

    What is the term for a molecule or ion capable of donating a proton (H+)?

    <p>Acid</p> Signup and view all the answers

    What is the primary role of the kidney in regulating acid-base balance?

    <p>To reabsorb bicarbonate from the urine</p> Signup and view all the answers

    What is the term for a disturbance in which the body has too much acid?

    <p>Acidosis</p> Signup and view all the answers

    What is the term for a disturbance in which the body has too much base?

    <p>Alkalosis</p> Signup and view all the answers

    What is the ratio of HCO3- to H2CO3 in normal arterial blood?

    <p>20:1</p> Signup and view all the answers

    How do the kidneys respond to a decrease in HCO3- levels in the blood?

    <p>Reabsorb and synthesize HCO3-</p> Signup and view all the answers

    What is the pH of the renal tubular fluid when the Na+ – H+ exchange system stops?

    <p>4.5</p> Signup and view all the answers

    What is the main mechanism by which the lungs regulate H2CO3 levels?

    <p>Ventilation</p> Signup and view all the answers

    What happens to H2CO3 levels in the blood during hyperventilation?

    <p>H2CO3 levels decrease</p> Signup and view all the answers

    What is the role of the kidneys in regulating the metabolic component of the acid-base balance?

    <p>Excrete and reabsorb HCO3-</p> Signup and view all the answers

    What is the effect of an increase in H+ concentration on the respiratory center?

    <p>It increases the rate of ventilation</p> Signup and view all the answers

    What is the pK of the buffer at 37°C?

    <p>6.1</p> Signup and view all the answers

    Study Notes

    Respiratory Compensation

    • Respiratory compensation is fast and reaches maximal capacity in 24 hours
    • Changes in ventilation affect the denominator (respiratory) component of the H-H equation

    Combined Regulation of the HCO-3 / H2CO3 Buffer System

    • The ultimate aim of regulation is to maintain a ratio of 20 Bicarbonate : 1 Carbonic Acid
    • At this ratio, arterial blood pH = 7.40 ± 0.05
    • Kidneys regulate the metabolic component (HCO-3)
    • Lungs regulate the respiratory component (H2CO3)
    • Regulation also includes compensation for excess or deficiency of the other

    Disturbances in Acid-Base Balance

    • There are four types of acid-base disturbances:
      • Metabolic acidosis
      • Metabolic alkalosis
      • Respiratory acidosis
      • Respiratory alkalosis

    Metabolic Acidosis

    • Happens due to:
      • Build-up of acid in blood
      • Excess HCO3- loss by excretion via kidney or diarrhea
    • Results in:
      • Low HCO3- in blood
      • Disruption of HCO3-/ H2CO3 ratio
    • The body tries to maintain the HCO3-/ H2CO3 ratio of 20:1 to keep the pH 7.40

    Kidney Regulation of Bicarbonate

    • Kidneys regulate the metabolic (HCO3-) component
    • Depending on the acid-base status, kidneys may:
      • Excrete HCO3- in urine
      • Reabsorb HCO3- partially or completely
      • Synthesize HCO3- by renal tubules
    • Changes introduced by the kidneys affect the numerator of the H-H equation
    • HCO3- synthesis, excretion, or reabsorption involves the Na - H+ exchange mechanism by the kidney tubules

    Lung Regulation of H2CO3

    • Lungs regulate the respiratory (H2CO3) component
    • Regulation is mainly by ventilation, i.e., Hypoventilation or Hyperventilation
    • In hypoventilation:
      • CO2 is retained
      • pCO2 in alveolar spaces ↑
      • H2CO3 in the blood ↑
    • In hyperventilation:
      • CO2 is exhaled "blown off"
      • pCO2 in alveolar space ↓
      • H2CO3 in the blood ↓

    Terminology

    • Homeostasis is the state of internal balance to maintain physical and chemical conditions by living systems
    • Acid is a molecule or ion capable of donating a proton (H+)
    • Base is a substance that dissociates in aqueous solution to form hydroxide ions OH−
    • Buffers are substances that maintain a constant pH by neutralizing the effects of hydrogen ions
    • pH is a measure of how acidic/basic water is or a measure of the concentration of hydrogen ions in an aqueous solution
    • pK is the pH value at which a chemical species will accept or donate a proton

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    Description

    This quiz covers the regulation of the bicarbonate/carbonic acid buffer system, including the ultimate aim of maintaining a specific ratio to maintain arterial blood pH.

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