Acid Base Balance Flashcards
What are the features of a good buffer?
abundant and the pKa of the acid should be close to the pH you’re trying to regulate
What is the normal pH of the body?
7.4
What enzyme is required for bicarbonate to act as a buffer?
carbonic anhydrase
Where is there the most carbonic anhydrase?
red blood cells
What is the pK for the buffer reaction?
6.1
How do you alter blood pH?
by altering the ratio of CO2 and HCO3-
How do you change the concentration of CO2?
change ventilation
How do you change the concentration of HCO3-?
change the amount of bicarbonate that is reabsorbed and secreted in the kidney
What other buffers are present in the body apart from bicarbonate?
plasma proteins, phosphate, haemoglobin
What are the normal causes of acid production in the body?
lactic acid from anaerobic metabolism, keto acids from breakdown of fatty acids, GI secretions
What is the normal anion gap?
12mmol
What is the normal anion gap due to?
plasma proteins
When will you see a high anion gap?
lactic acidosis, diabetic ketoacidosis, renal failure
How does the kidney reabsorb bicarbonate?
in the proximal tubule there is a sodium hydrogen exchanger which will secrete hydrogen into the lumen where it will react with the bicarbonate with carbonic anhydrase to make CO2 which can diffuse across the membrane into the cell where it reacts with the carbonic anhydrase to go back into bicarbonate and hydrogen ions. The hydrogen ions are recycled and the bicarbonate is reabsorbed via a pump.
What will chronic vomiting lead to?
metabolic alkalosis
What will chronic diarrhoea lead to?
metabolic acidosis
What will chronic renal failure lead to?
metabolic acidosis
What will starvation lead to?
metabolic acidosis (due to ketoacidosis)
When do you see a high level of bicarbonate?
in metabolic alkalosis and in respiratory acidosis (as compensation)
When do you see a low level of bicarbonate?
in metabolic acidosis and in respiratory alkalosis (as compensation)
What happens to potassium in metabolic acidosis?
get hyperkalemia because the potassium will be drawn out of cells as H+ goes in to them and because the kidney will excrete H+ ions instead of K+ but the hyperkalemia shows an artificial elevation
