C - Acid Base Handling (E) Flashcards
normal pH
7.35 to 7.46
what is a buffer
weak acid and its base
list 3 main biological buffers
bicarbonate
haemoglobin
phosphate
(also protein and bone)
how can acid base balance be maintained in short and long term
short = bicarb
long = excretion of H+ in kidneys
how can bicarb be regenerated
by carbonic acid (water and CO2)
how are H+ excreted out of kidney cells
transport system with sodium
how is co2 produced in body
aerobic metabolism of proteins / carbs / fats
how is co2 balanced in body
increased resp rate to blow it off
what is the main buffer in red blood cells
haemoglobin
how is Hb a buffer for CO2
co2 binds to water producing bicarb and H+, the H+ then binds to Hb to make HHb
causes of metabolic acidosis
increased H+ production - DKA
decreased H+ excretion - renal tubular acidosis / renal failure
bicarb loss - intestinal fistula
primary abnormalities in metabolic acidosis
increased H+
decreased pH
how can metabolic acidosis be compensated
fall in CO2 due to increased RR - reduces rise in H+
give H+ conc and arterial PCO2 of
metabolic acidosis
low pH, low CO2
give H+ conc and arterial PCO2 of resp alkalosis
high pH, low CO2
give H+ conc and arterial PCO2 of resp acidosis
low pH, high CO2
give H+ conc and arterial PCO2 of metabolic alkalosis
high pH, high CO2
how are pH and H+ linked
inversed log - as H+ increases, pH decreases
what is the primary abnormality in resp acidosis
increased CO2
–> increased H+ and slight increase in bicarb
causes of resp acidosis
decreased ventilation
poor lung perfusion
impaired gas exchange
how does the body compensate for resp acidosis
increased renal excretion of H+, plus increased generation of bicarb
how does the lung vs kidney compensation speed compare
lungs are much quicker
what are the H+ / CO2 / bicarb levels like in chronic resp acidosis
H+ near normal, but CO2 and bicarb elevated
primary abnormality in metabolic alkalosis
decreased H+ / increased pH
increased bicarb
causes of metabolic alkalosis
H+ loss eg pyloric stenosis
hypokalaemia
ingestion of xs bicarb
how is metabolic alkalosis compensated for
increased CO2
- inhibiting respiratory centre (limited as you would die from not breathing)
what is the primary abnormality in resp alkalosis
low Co2
then low H+ and bicarb
causes of resp alkalosis
hyperventilation
- voluntary eg anxiety
- artificial ventilation
- stimulation of resp centre by drugs
how does chronic resp alkalosis affect kidneys
reduced renal excretion of H+
reduced bicarb generation
still low co2 and bicarb even if pH normalises
