Renal Physiology Lecture 3: Acid-Base Disturbances

Question 1

directions for acid-base disturbances

Answer 1

• above 7.7 → alkalosis
• below 7 → acidosis

Question 2

Causes for acid-base disturbances

Answer 2

• Metabolic
  
  • Acids or bases not derived from carbon dioxide
• Respiratory
  
  • Due to hypo or hyperventilation

Question 3

Buffer system when plasma pH is altered

Answer 3

If plasma pH is altered, buffer system has already failed

Question 4

What compensates of pH disturbances if cause is metabolic vs. respiratory?

Answer 4

• respiratory → only kidneys can compensate
• metabolic → respiratory and renal can contribute

Question 5

Respiratory acidosis

Answer 5

Renal compensation: hydrogen is excreted, bicarbonate reabsorbed.

• Hypoventilation increases carbon dioxide accumulation
• Drug or alcohol effects
• Increased airway resistance
• Impaired alveolar gas exchange → pneumonia
• Muscular dystrophy
• COPD → most common

Question 6

Metabolic acidosis

Answer 6

Respiratory compensation eliminates excess carbon dioxide (hyperventilation). Renal compensation: hydrogen excretion and bicarbonate reabsorption.

• Dietary & metabolic input of hydrogen ion exceeds excretion
• Lactic acidosis → anaerobic metabolism
• Ketoacidosis
• Ethylene glycol ingestion → antifreeze
• Loss of bicarbonate

Question 7

Respiratory Alkalosis

Answer 7

Renal compensation: excretion of bicarbonate to further reduce buffer load and increase hydrogen ion concentration to restore pH

• Hyperventilation
  
  • i.e. excessive mechanical ventilator
  • anxiety
• Carbon dioxide falls

Question 8

Respiratory acidosis

Answer 8

Respiratory compensation: hypoventilation restores carbon dioxide. Renal compensation: bicarbonate excretion and hydrogen reabsorption.

• Excessive vomiting of acidic stomach contents
• Excessive ingestion of antacids (contain HCO3-)
• Low hydrogen ion concentration