السؤال

Acid base balance

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ريما حسن آل ناصر
دكتور صيدلي

الأجوبة

Acid-base balance refers to the regulation of the pH levels in the body to maintain homeostasis, ensuring that bodily fluids are neither too acidic nor too alkaline. The body maintains a normal blood pH between 7.35 and 7.45, which is slightly alkaline. This balance is crucial for proper cellular function and metabolism.

 

 Key Components of Acid-Base Balance:
1. Buffer Systems:
   - Bicarbonate buffer system: The most important system, where carbonic acid (H₂CO₃) and bicarbonate (HCO₃⁻) help maintain the pH of the blood.
   - Protein buffer system: Proteins, particularly hemoglobin in red blood cells, can absorb or release hydrogen ions (H⁺).
   - Hemoglobin buffer system: In red blood cells, hemoglobin helps buffer hydrogen ions produced by carbon dioxide.

2. Respiratory Regulation: The lungs regulate the levels of carbon dioxide (CO₂) in the blood. CO₂ combines with water to form carbonic acid, which dissociates into bicarbonate and hydrogen ions, influencing pH. By increasing or decreasing the rate of breathing, the body can expel CO₂ and affect blood pH.

3. Renal Regulation: The kidneys help maintain acid-base balance by excreting hydrogen ions (H⁺) and reabsorbing bicarbonate (HCO₃⁻). This process is slower than respiratory regulation but is long-term and more powerful in maintaining balance.

 

Acid-Base Disturbances:
- Acidosis: When the blood pH falls below 7.35, leading to a more acidic environment.
  - Respiratory acidosis: Caused by CO₂ retention (e.g., due to chronic obstructive pulmonary disease, or COPD).
  - Metabolic acidosis: Caused by an accumulation of acids or loss of bicarbonate (e.g., diabetic ketoacidosis, renal failure).
  
- Alkalosis: When the blood pH rises above 7.45, resulting in a more alkaline environment.
  - Respiratory alkalosis: Caused by excessive CO₂ loss (e.g., hyperventilation).
  - Metabolic alkalosis: Caused by an excess of bicarbonate or loss of acid (e.g., vomiting, excessive antacid use).

 

Compensation:
The body compensates for changes in pH through respiratory and renal mechanisms:
- Respiratory compensation: If metabolic acidosis occurs, the lungs will increase breathing rate to expel CO₂, raising pH.
- Renal compensation: If respiratory acidosis occurs, the kidneys will increase the excretion of hydrogen ions and reabsorb bicarbonate to reduce acidity.

Maintaining acid-base balance is vital for cellular activities, enzyme function, and overall health.

عبدالله سعيد ال غواء
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