Lecture Notes on pH and Acid-Base Regulation

Introduction to pH

• pH indicates acidity.
• Blood pH is strictly regulated between 7.35 and 7.45.
• Minor changes in pH can impact protein stability and biochemical processes.

Carbon Dioxide and Blood Acidity

• Normal cellular metabolism produces carbon dioxide, leading to the formation of carbonic acid.
• Carbonic acid dissociates into hydrogen ions and bicarbonate.

Chemical Equilibrium

• The equilibrium between carbon dioxide, hydrogen ions, and bicarbonate is dynamic.
• Shifts in concentration affect the balance and pH of blood.

Mechanisms of pH Regulation

1. Pulmonary Regulation

• Exhalation of carbon dioxide helps regulate blood acidity.
• Decreased pH is detected by chemoreceptors, increasing breathing rate.
• Rapid response, effective within minutes to hours.

2. Renal Regulation

• Excretion of hydrogen ions and reabsorption of bicarbonate by kidneys.
• Slower response, taking days.
• Proximal tubule reabsorbs bicarbonate; collecting duct generates new bicarbonate.

Ammonia Buffering System

• Important for excreting acids in urine.
• Ammonia production regulated by acidity levels, unlike phosphate.

Factors Influencing Acid Excretion

• Blood pH, potassium, chloride concentrations, and hormones.

Acid-Base Disturbances

Acidosis

• Respiratory Acidosis: Lungs inadequately function, leading to CO2 accumulation.
• Metabolic Acidosis: Excessive metabolic acid production, decreased renal excretion.

Alkalosis

• Respiratory Alkalosis: Increased ventilation causes excessive CO2 exhalation.
• Metabolic Alkalosis: Acid loss or bicarbonate retention.

Terms to Know

• Acidemia: Blood too acidic.
• Alkalemia: Blood too basic.

Conclusion

• Blood pH regulation is crucial, influenced by multiple physiological processes.
• Suggestions for future topics are encouraged.