Acid-Base Balance in Blood pH

Blood pH

• Normal blood pH range is 7.35-7.45
• Blood pH is maintained within a narrow range due to cell functions being pH-sensitive
• Enzymes, receptors, ion channels, and transporters are all pH-sensitive
• Acidosis occurs when plasma levels fall below 7.35
• Alkalosis occurs when plasma levels rise above 7.45
• These imbalances affect all body systems, leading to potential complications like coma, cardiac failure, and circulatory collapse
• Acidity measured by H+ concentration
• Normal pH 7.4

Acid-Base Balance

• The normal pH of systemic arterial blood is 7.35-7.45 is maintained through
• Homeostasis maintained by:
  • Buffer systems (proteins, carbonic acid-bicarbonate buffers, phosphates)
  • Respiration (exhalation of CO2)
  • Kidney (excretion of H+ and reabsorption of HCO3-)

Buffers

• Chemical buffers react within fractions of a second
• Examples of chemical buffers include
  • Bicarbonate buffer system
  • Phosphate buffer system
  • Protein buffer system
• Physiological buffers (respiratory and urinary systems) react over hours to days.

The Respiratory System

• Adjusts pH by regulating CO2 levels
  • High pH (alkalosis): faster breathing to remove CO2
  • Low pH (acidosis): slower breathing to retain CO2

The Kidney

• Reacts over hours to days
• Excretes excess H+ or retains bicarbonate depending on pH
• Reabsorption and secretion of bicarbonate
• Secretion of H+ maintaining pH by acidifying urine.

Acid-Base Disorders

• Changes in arterial PCO2, serum HCO3-, and serum pH
• Categories:
  • Respiratory acidosis
  • Respiratory alkalosis
  • Metabolic acidosis
  • Metabolic alkalosis

Specific Acid-Base Disorders

• Respiratory Acidosis: Hypoventilation (slow or shallow breathing)
• Respiratory Alkalosis: Hyperventilation (rapid or deep breathing)
• Metabolic Acidosis: Excess acid or loss of bicarbonate
• Metabolic Alkalosis: Loss of acid or excess of bicarbonate

Effects of Acidosis

• H+ diffuses into cells, displacing K+, leading to hyperkalemia
• Depresses the central nervous system causing confusion, disorientation, and eventually coma

Effects of Alkalosis

• H+ diffuses out of cells, K+ enters cells, leading to hypokalemia
• Nervous system is hyperexcitable leading to muscle spasms, tetany, convulsions, and ultimately, respiratory paralysis

Explore the vital concepts of blood pH and acid-base balance in this quiz. Understand the mechanisms that maintain normal pH levels and the implications of acidosis and alkalosis on body function. Test your knowledge on buffers and homeostasis.