Buffer Systems and Acid-Base Balance

Buffer Systems and Acid-Base Balance

• Buffer systems resist changes in pH, essential for maintaining a stable internal environment.
• Chemical Buffer Systems work by neutralizing excess acids or bases. These systems react with acids and bases to prevent significant changes in pH. 
• Physiological Buffer Systems include the lungs and kidneys which play a crucial role in regulating acid-base balance.

Major Buffer Systems in the Body

• Bicarbonate Buffer System is the primary buffer system.
  • Lungs regulate carbonic acid (H2CO3) production by managing CO2 levels.
  • Kidneys regulate bicarbonate (HCO3-) production.
• Lungs control CO2 content in the extracellular fluid (ECF) by adjusting ventilation.
  • Increased CO2 leads to hyperventilation (increased respiratory rate).
  • Reduced CO2 leads to hypoventilation (decreased respiratory rate).
• Kidneys regulate HCO3- in the ECF by either reabsorbing or excreting acids and bases into urine.
  • Acidosis stimulates kidney excretion of H+ and conservation of HCO3-.
  • Alkalosis causes the kidneys to retain H+ and excrete HCO3-.
• Phosphate Buffer System is essential for regulating pH in intracellular fluid (ICF) and urine.
  • Consists of mono and dihydrogen phosphate ions (HPO₄²⁻/H₂PO₄⁻).
  • Neutralizes excess acid by reacting with monohydrogen phosphate, increasing dihydrogen phosphate.
  • Neutralizes excess base by reacting with dihydrogen phosphate, increasing monohydrogen phosphate.
• Protein Buffer System helps regulate pH in both ECF and ICF.
  • Proteins are chains of amino acids containing amine (– NH2) and carboxyl (–COOH) groups.
  • Amine groups (NH2) bind to excess H+ (acid) in the blood.
  • Carboxyl groups (COOH) release H+ (acid) in the blood to combat excess base.

Acid-Base Imbalance

• Acidosis occurs when pH is below 7.35, meaning there is an accumulation of acids or loss of bases (HCO3-).
• Alkalosis occurs when pH is above 7.35, indicating an accumulation of bases or loss of acids.

Respiratory Acidosis:

• Occurs when the lungs cannot remove enough CO2 from the body leading to CO2 accumulation in the blood, causing a low pH.
• Caused by:
  • Respiratory center depression (hypoventilation)
  • COPD
  • Narcotics
  • Respiratory arrest
  • Paralysis of respiratory muscles
• Causes:
  • Decreased excitability of the central nervous system (CNS)
  • Headache, drowsiness, disorientation, coma
  • Cardiovascular issues: dysrhythmias, decreased cardiac contractility, hypotension.
  • Hypercalcemia: acidosis decreases Ca++ binding to albumin, increasing serum ionized Ca++ levels.

Metabolic Acidosis:

• Caused by loss of bicarbonate or an increase in acid generation.
• Symptoms resemble respiratory acidosis, but the primary cause is HCO3 loss.

Respiratory Alkalosis:

• Caused by a decrease in CO2 levels in the blood due to hyperventilation (increased excretion by the lungs).
• Caused by:
  • Hyperventilation
  • Hypoxemia (low blood oxygen)
  • Fever
  • Anger
  • Psychological dyspnea: anxiety-induced hyperventilation, experiencing shortness of breath
• Causes:
  • Increased excitability of the CNS
  • Lightheadedness, numbness, tingling, confusion, blurred vision
  • Cardiovascular issues: increased cardiac contractility, hypertension
  • Hypokalemia: increased blood pH causes shift of K out of plasma and interstitial fluids into urine.

Metabolic Alkalosis

• Characterized by an accumulation of bicarbonate in the body.
• Most commonly caused by loss of stomach acid due to excessive vomiting.

Explore the critical role of buffer systems in maintaining pH stability in the human body. This quiz covers chemical and physiological buffer systems, including the bicarbonate buffer system, and the functions of the lungs and kidneys in regulating acid-base balance.