Acid base regulation Flashcards
effect, and body’s response to hyperventilation
CO2 lost - increase in pH - resp alkalosis - compensatory change in renal func (H+ increase, HCO3- loss) - pH reduced ie restored
effect, and body’s response to hypoventilation
CO2 retention - increase pH - resp acidosis - comp change in renal function - HCO3- gain, H+ loss - increae in pH - pH restored
effect, and body’s response to change in renal func = HCO3- loss and H+ gain
decrease pH - metabolic acidosis - comp change in lung func - increase ventilation - CO2 blown off - increase pH
effect, and body’s response to change in renal func = HCO3- gain and H+ loss
pH increase - met alkalosis - change in lung func - hypovent - co2 retention - increase pH
what type of compensation - met/resp - is faster
resp
what is the normal pH
7.35-7.45
where does the acid come from in the body
13000mmols/d volatile acid excreted by lungs = 99%
100mmols/d excreted by the kidney = 1%
normal physiological H+ conc
40nmol/L
normal urine pH
there is no normal urine pH
it is the regulator to ensure the plasma pH stays constant
normal arterial bicarbonate
22-26mEq/l
describe bicarbonate
it is a high capacity chemical buffer
responds quickly to changes in metabolic acid
and can be produced from volatile resp acid
bicarbonate reabsorption
reabsorbed at different points along the nephron - 80% in PCT 10% ascending limb 6% DCT 4% collecting duct
why is all of the bicarbonate reabsorbed
it is a useful buffering system in the intracellular and extracellular environment
what is the Henderson-hasselbach eqn
pH = pKa + log10 [HCO3-]/[CO2]
constant value for pKa
6.1
normal value of HCO3- used in Henderson-hasselbach eqn
24mmol/L
normal [CO2}
1.2mmol/L
effect of changing [co2]
inverse effect on pH
effect of changing [HCO3-]
direct effect on pH
what is the davenport diagram
a graphical representation of the association between pH, bicarbonate and CO2 in blood
describe the axis of the davenport diagram
Y - plasma bicarb conc mmol/L
bottom X - pH
top X - {H+] nmol/L
pCO2 (Kpa) is inside the graph and not a linear scale
describe what is seen on the davenport diagram
normal pH is a vertivcal line
normal bicarb - horizontal line
normal zone - circle where these lines cross
met alkalosis - pH and bicarb increase (drive the alkalosis) - follow the CO2 line
met acidosis - H+ increase- pH decrease - follow the CO2 lines
acute resp alk - pH up, bicarb down, CO2 down
chronic resp alkalosis - same as acute but closer to the normal line - more time for compensation
acute resp acidosis - pH decrease, CO2 and bicarb increase
chronic resp acidosis - same but closer to normal
why are resp disorders split into acute and chronic
rapid changes that quickly change the acid-base homeostasis/long slow
what happens of the result is at the extremes of bircarb but normal pH in the davenport diagram
there is full compensation - pH is fine buyt there is a disturbance
