Acid-Base Balance Study Notes

Acid-Base Balance Study Notes

Respiratory Regulation

• Mechanism: CO2 removal through ventilation regulates blood pH.
• Hyperventilation: Decreases CO2, increases pH (respiratory alkalosis).
• Hypoventilation: Increases CO2, decreases pH (respiratory acidosis).
• Response time: Rapid response, typically within minutes.

Acidosis

• Definition: A condition where blood pH falls below 7.35.
• Types:
  • Respiratory Acidosis: Due to CO2 retention (e.g., chronic obstructive pulmonary disease, hypoventilation).
  • Metabolic Acidosis: Due to excess acid or loss of bicarbonate (e.g., diabetic ketoacidosis, renal failure).
• Compensatory Mechanisms:
  • Respiratory system increases ventilation to expel CO2.
  • Kidneys increase bicarbonate reabsorption.

Alkalosis

• Definition: A condition where blood pH rises above 7.45.
• Types:
  • Respiratory Alkalosis: Due to excessive CO2 elimination (e.g., anxiety, high altitude).
  • Metabolic Alkalosis: Due to excess bicarbonate or loss of acid (e.g., vomiting, diuretic use).
• Compensatory Mechanisms:
  • Respiratory system decreases ventilation to retain CO2.
  • Kidneys decrease bicarbonate reabsorption.

Renal Regulation

• Role: Kidneys manage acid-base balance by excreting H+ and reabsorbing bicarbonate.
• Response time: Slower, takes hours to days for significant changes.
• Mechanisms:
  • Bicarbonate reabsorption: Primary method to regulate pH.
  • Ammonium excretion: Binds H+ ions, further aiding in acid elimination.
• Acid-base disturbance: Chronic conditions affect kidney function leading to metabolic imbalances.

Buffer Systems

• Definition: Systems that minimize pH changes by neutralizing acids or bases.
• Main Buffer Systems:
  • Bicarbonate Buffer System: HCO3- and H2CO3; regulates pH in extracellular fluid.
  • Protein Buffer System: Proteins can accept or donate H+ ions; significant in intracellular fluid.
  • Phosphate Buffer System: H2PO4- and HPO4^2-; important in renal function and intracellular fluid.
• Immediate response: Buffer systems act quickly to stabilize pH before respiratory and renal adjustments.

Respiratory Regulation

• CO2 removal through ventilation is crucial for maintaining blood pH.
• Hyperventilation leads to decreased CO2 levels, resulting in increased pH, known as respiratory alkalosis.
• Hypoventilation causes CO2 retention and decreased pH, referred to as respiratory acidosis.
• The respiratory system can respond rapidly, typically within minutes, to changes in blood pH.

Acidosis

• Acidosis occurs when blood pH drops below 7.35.
• Types include respiratory acidosis, resulting from CO2 retention, and metabolic acidosis, arising from excess acid or bicarbonate loss such as in diabetic ketoacidosis or renal failure.
• Compensatory responses involve increased ventilation by the respiratory system and enhanced bicarbonate reabsorption by the kidneys.

Alkalosis

• Alkalosis is defined as a blood pH above 7.45.
• Types include respiratory alkalosis due to excessive CO2 elimination (e.g., during anxiety or high-altitude exposure) and metabolic alkalosis from excess bicarbonate or acid loss (e.g., vomiting or diuretic use).
• Compensatory mechanisms include decreased ventilation to retain CO2 and reduced bicarbonate reabsorption by the kidneys.

Renal Regulation

• The kidneys play a critical role in acid-base balance by excreting hydrogen ions (H+) and reabsorbing bicarbonate.
• Renal responses to pH changes are slower, typically taking hours to days for significant adjustments.
• Key mechanisms include bicarbonate reabsorption, which is the primary method for regulating pH, and ammonium excretion, which aids in acid elimination.
• Chronic conditions can impair kidney function, leading to metabolic imbalances.

Buffer Systems

• Buffer systems function to minimize pH fluctuations by neutralizing acids and bases.
• The bicarbonate buffer system, composed of HCO3- and H2CO3, primarily regulates pH in extracellular fluid.
• The protein buffer system involves proteins that can accept or donate H+ ions, playing a significant role within intracellular fluid.
• The phosphate buffer system, consisting of H2PO4- and HPO4^2-, is vital for renal function and intracellular fluid balance.
• Buffer systems provide an immediate response to stabilize pH prior to adjustments by respiratory and renal systems.

Rh Factor

• Rh factor indicates the presence (+) or absence (-) of the RhD antigen on red blood cells.
• Rh-positive (Rh+) individuals possess the antigen, while Rh-negative (Rh-) individuals do not.
• Inheritance is governed by the RHD gene, where Rh+ is the dominant trait.
• Rh incompatibility in pregnancy can result when an Rh- mother has an Rh+ baby, potentially causing hemolytic disease of the newborn (HDN).

Transfusion Compatibility

• ABO blood groups consist of four main types: A, B, AB, and O, each requiring careful compatibility for blood transfusions.
• Type A has anti-B antibodies, allowing transfusions from A or O types.
• Type B has anti-A antibodies and can receive B or O.
• Type AB lacks antibodies and can receive blood from all groups, making it the universal recipient.
• Type O has both anti-A and anti-B antibodies and can only receive O blood, qualifying it as the universal donor.
• It’s essential for Rh- individuals to receive Rh- blood to prevent adverse reactions, whereas Rh+ individuals can receive both Rh+ and Rh-.

Immune Response To Blood Types

• The immune system produces antibodies against foreign antigens, leading to possible complications during transfusions.
• For instance, Type A blood produces anti-B antibodies; introducing Type B blood triggers an immune response.
• A hemolytic reaction occurs when incompatible blood types mix, causing destruction of red blood cells and severe health issues.
• Sensitization can happen when Rh- individuals are exposed to Rh+ blood, prompting antibody production that may complicate future pregnancies or transfusions.

Blood Typing Methods

• Forward typing assesses the presence of antigens on red blood cells using known antibodies to identify blood type.
• Reverse typing checks for antibodies in serum against known blood types to confirm compatibility.
• Gel testing utilizes a gel medium for separating blood cells based on antigen-antibody reactions.
• Molecular typing employs DNA analysis for precise blood type determination, especially valuable for rare types and Rh status.
• Accurate blood typing is critical for ensuring safe blood transfusions, organ transplants, and effective pregnancy management.

This quiz covers the mechanisms of acid-base balance regulation, including respiratory acidosis and alkalosis. It explores conditions affecting blood pH and compensatory mechanisms in response to these acid-base disturbances. Test your understanding of these critical physiological concepts.