Acid-Base Balance Flashcards
What is the normal physiological range pH in blood?
7.35 - 7.45
Where is CO2 produced?
Where is the acid produced?
What happens to CO2 and oxygen in cells in relation to erythrocytes and plasma?
CO2 production: oxidative metabolism 13,000 - 15,000 mmol CO2 /day
• Acid production: dietary phosphoproteins and sulphur-containing proteins 50 - 100 mmol H+ /day
CD is carbonic anyhydrase - this is the rate limiting step as this is an enzyme
What is the equation for the buffering of bicarbonate, co2 and h+
What buffers are in the kidney and what part of the kidney control bicarbonate reabsorption?
What is the main buffer systems in the plasma, ecf,icf and eryhtrocyte?
pH = HCO3 / PCO2
What happens to HCO3 in acidosis?
What happens to HCO3 in alkalosis?
When is an acidosis fully compensated
Acidosis can arise by: (1) a fall in HCO3 with normal PCO2 (2) a rise in PCO2 with normal HCO3
Alkalosis can arise by: (1) a rise in HCO3 with a normal PCO2 (2) a fall in PCO2 with a normal HCO3
If a disease process altered the concentration of one of the components, the ratio and therefore pH can be returned to normal if the other component concentration is sufficiently altered in the same direction
If the pH is restored to normal, compensation is said to have occurred. Complete if pH is restored to normal and partial if pH is near normal
Metabolic acidosis
How long does compensation take?
How do you compensate?
Compensation takes 12 - 24 hours
Mechanism: respiratory stimulation - decrease PCO2
PCO2 decrease by 0.75-0.80 kPa for every 4 mmol/L decrease in HCO3
Metabolic alkalosis
How long does compensation take and what is the mechanism?
Compensation takes 12-24 hours
Mechanism: respiratory depression -> increase in PCo2
Increase PCO2 by 0.5kPa for every 4mmol/L increase of HCO3
Respiratory Alkalosis
How long does compensation take?
Compensation takes 2 - 4 days
Mechanism: renal compensatio -> decrease HCO3
Decrease in HCO3 by 1.5mmol/L for every 0.4 kPA decrease in PCO2
Respiratory acidosis
How long does compensation take
What is the mechanism
Compensation takes 2 - 4 days
Mechanism: renal compensatio -> increase HCO3
increase in HCO3 by 3 mmol/L for every 1 kPA decrease in PCO2
Practical approach to intepreration of acid/base data
What does this person have?
Is it compensated or not compensated?
what is a potential cause of this?
Uncompensated Respiratory acidosis
Lung disease: Emphysema, Bronchitis, Asthma
- Neuromuscular: Guillain-Barre syndrome
- Central NS: Trauma Infection Tumours
- Drugs: Sedatives Anaesthetics
- Mechanical ventilation
Causes of Metabolic Acidosis
Think of what can increase H+ load, decrease H+ secretion, and increase loss of HCO3
Causes of metabolic alkalosis
What are causes of respiratory acidosis?
Causes of respiratory alkalosis
What does this person have?
Acute Diabetic ketoacidosis
Acute respiratory acidosis
