Control of Acid-base Balance Flashcards
What are the two ways that acid is produced in the body?
Acid is produced in the body through
- Respiratory acid (CO2)
- Metabolic acid (h+)
What is the difference between respiratory and metabolic acid in the way that they are generated, the amount and how are they excreted?
Respiratory acid is produced through the breakdown of glucose whereas metabolic acid is produced through the breakdown of amino acids
Respiratory acid is produced in large amounts in comparison to metabolic acid
Respiratory acid is excreted via the lungs whilst metabolic acid is excreted through the kidney
What are the two main effects of acid-base disorders on the body?
Acid base disorders alters protein structures such as enzymes, protein channels and pumps
It also affects oxygen binding to haemoglobin (according to the Bohr effect)
What are the three different mechanisms and the speed to which they work that the body employs in maintaining the appropriate pH in the body?
Buffering of the body fluid is immediate in maintaining the pH
Excretion of carbon dioxide and hydrogen ions through the lungs is also quick and only take seconds
Renal excretion of hydrogen ions and bicarbonate (HCO3-) is slow and would take around 2 days
With regards to the body’s system of buffering to maintain pH, what are the four main types of buffers that the body uses?
Haemoglobin in red blood cells
Bicarbonates (ECF) which is the main buffer
Plasma proteins (ICF)
Phosphates (ECF)
Amongst the four main types of buffers that the body employs, which is the most important and for what reason?
What is then the second and least most important buffer systems?
Bicarbonate is the main and most important buffer because carbon dioxide and bicarbonate concentrations in the body are high
CO2+H2OH2CO3H++HCO3-
Haemoglobin is involved in 80% of non-bicarbonate buffering making it the second and phosphate buffering is the least important
What is the Henderson-hasselbach equation used for?
It is used in determining the pH if all the other factors are known. It is also used to determine the primary cause/compensation of the disorder
What is respiratory acidosis, how does it occur and how does the body compensate for it?
Respiratory acidosis occurs when there is inadequate excretion of carbon dioxide leading to hypercapnoea.
The causes are usually non-pulmonary due to factors such as central reps drive, neural linkage to resp muscle, pulmonary diseases or weakness in respiratory muscle
The body attempts to compensate with the kidney increasing bicarbonate concentration. However this does not completely normalise the pH and it results in both increases in bicarbonate and hydrogen ion concentration
What is respiratory alkalosis, how does it occur and how does the body compensate for it?
Respiratory alkalosis is essentially hyperventilation
The causes are due to a fall in carbon dioxide levels, hypoxia resulting TNT increase in firing of aortic and carotid bodies and stretch receptors in lung diseases being impaired
The body attempts to compensate by reducing bicarbonate. The result is reduction in both bicarbonate and carbon dioxide concentration
A patient presents with a blood pH of >7.45 and paCO2 of <35mmHg, indicators of respiratory alkalosis. What is the appropriate treatment that should be prescribed?
Increase oxygen levels because hypoxaemia is the most common cause of respiratory alkalosis
What is the rule of thumb regarding the 4 basic types of acid-base disorders?
Respiratory acidosis/alkalosis is due to changes in plasma CO2
Metabolic acidosis/alkalosis is due to changes in hydrogen (H+) ions and bicarbonate (HCO3-) concentration
