Acid-base balance- Metabolic Acidosis & Alkalosis

Question 1

describe the mechanism of metabolic acidosis

Answer 1

excess H+ from any source other than CO2

Question 2

describe the [HCO3] seen in metabolic acidosis

Answer 2

decreased, either due to being used as buffer for excess H+ or because low [HCO3] is cause of acidosis

Question 3

describe the respiratory compensation of metabolic acidosis

Answer 3

ventilation is increased to blow off more CO2, therefore [H+] is lowered raising pH to normal, also causes further decrease in [HCO3]

Question 4

describe the renal correction of metabolic acidosis

Answer 4

HCO3 very low so readily reabsorbed, H+ secretion high so excreted(NH4 + titratable acid), this generates more HCO3
only then can ventilation be normalised(ie not compensating for acidosis)

Question 5

describe why respiratory compensation is essential in metabolic acidosis, and why renal correction is insufficient alone

Answer 5

because acid cannot be excreted by kidneys immediately, it takes time, so compensation by respiratory is needed

Question 6

what is more common, metabolic acidosis or alkalosis

Answer 6

acidosis much more common

Question 7

describe the mechanism of metabolic alkalosis

Answer 7

excessive loss of H+ from the body, or addition of base

Question 8

describe the effect on [HCO3] in metabolic alkalosis

Answer 8

loss of H+ or addition of base, results in increased [HCO3]

Question 9

describe the respiratory compensation of metabolic alkalosis

Answer 9

increased pH slows ventilation, CO2 is retained, therefore H+ increases, lowers pH, and [HCO3] also rises

Question 10

describe the renal correction of metabolic alkalosis

Answer 10

filtered [HCO3] so large that isn’t all reabsorbed, HCO3 is excreted, no acid is excreted, so [HCO3] returns to normal