Physiology 8 Flashcards
What is correction?
restoration of pH and bicarb and CO2 to normal
What is compensation?
restoration of pH irrespective of bicarb and CO2
What type of Hb has a higher affinity for hydrogen?
deoxygenated Hb
What is the Henderson Hasselbach equation?
pH= pKa + [A-]/[HA]
What is pKa?
the negative log of Ka
What is Ka?
The dissocation constant of an acid- a measure of how well the acid dissociates- also equal to H+*A-/HA
What causes a respiratory acidosis?
retention of CO2 by the body
What is generated when there is increased CO2?
increased H+ and HCO3-
What drives H+ secretion by the kidney?
PCO2
What happens in renal compensation for respiratory acidosis?
CO2 drives H+ secretion; all filtered HCO3- is reabsorbed and H+ continues to be secreted and generates TA and NH4+
What happens to HCO3- in renal compensation for respiratory acidosis?
furhter rises due to renal compensation
What does correction of respiratory acidosis require?
lowering of PCO2 by restoration of normal ventilation
What causes respiratory alkalsosis?
excessive removal of CO2 by the body
What happens when there is reduced CO2?
H+ and HCO3- decrease
What drives HCO3- reabsorption?
H+- HCO3- needs to bind with H+ to form carbonic acid and then CO2 and H2O to diffuse into the peritubular cells and then be reabsorbed
What happens with renal compensation for respiratory alkalosis to bicarbonate?
further lowers HCO3-
What is a metabolic acidosis?
excess H+ from any source other than CO2
What happens to bicarbonate with a metabolic acidosis?
buffers excess H+ so decreases
What does the decrease in plasma pH stimulate?
peripheral chemoreceptors which increase ventilation
What happens to the acid load in metabolic acidosis?
excreted
Why is respiratory compensation essential with metabolic acidosis?
acid load cannot be excreted immediately
What causes a metabolic alkalosis?
excessive loss of H+ from the body
What happens to bicarbonate with metabolic alkalosis?
rises
What effect does increased pH have on ventilation?
slows it down
What happens to bicarb during respiratory compensation for metabolic alkalosis?
rises furhter as CO2 is converted over
What is the correction for metabolic alkalosis?
bicarbonate is excreted as the filtered load is so large so not all is reabsorbed
