Session 4- Carbon Dioxide in the Blood Flashcards
buffer equation
CO2 + H2O H2CO3 H+ +HCO3-
what is the Henderson-Hassalbach equation for the bodys CO2-bicarbonate buffer system
pH = 6.1 + log10 ([HCO3-)/ 0.23 XPco2)
what is the normal pH range
7.35 -7.45
what is the acidic part of normal range
7.35.7.4
what is teh alkalotic part of normal range
7.4-7.45
in plasma what is the ratio of [HCO3-] to dissolved CO2
21:1
25mmol/L: 1.2mmol/L
why is the reaction with carbin dioxide and water more rapid in rbc
carbonic anhydrase is present
in what direction is the reaction drawn towards in a rbc
towards production of HC03- which depends primarily upon the buffering effects of Hb
what happens to the large amounts of HCO3- produced in arbc
exchanged with Cl-
what is the pH of the body fluids determined by
the amount of Co2 dissolved in plasma
the amount of HCO3- formed from CO2 in the rbc by a reaction involving hb
what controls HCO3- conc
kidney
what is the critical feature that is needed to maintain pH at 7.4
there is approximately 20 times as much Hc03- as dissolved CO2
what is the Haldene effect
low o2 conc increases co2 carrying capacity of hb because release of o2 from hb promotes binding of co2
what is the pCO2 in aterial blood
5.3kPa
what is the pCO2 in venous blood
6kPa
how is CO2 transported in the blood
10% as dissolved CO2
60% as bicarbonate
30% as carbamino compounds
what happens to the mixed venous blood when it reaches the lungs
teh oxygenation of Hb makes it a less good buffer and less good at holding CO2
the H+ ions are driven off Hb react with the bicarbonate to form CO2 which is breathed out
what does he law of mass action state
the rate of a chemical reaction is proportinal to the concentrations of the reacting substance
what compensates for the acid-base disorders
respiratory and renal systems by altering levels of bicarbonate and pCO2
lungs are fast responders able to chnage pCO2 in seconds/minutes
kidneys start changing bicarbonate concentration within hours
how does respiratory system compensation for metabolic acidosis occur
decreasing pCO2 through hyperventilation
there isnt enough bicarbonate to increase its levels to compensate for the increasing levels of CO2 so instead we lower CO2 through hyperventilation
in metabolic alkalosis how does the resp system compensate
hypoventiation to increase pCo2
issues with hypoventilation
our blood oxygen levels will drop
