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Lecture 9

BIOL 3070 Lecture Notes - Lecture 9: Haldane Effect, Ion Exchange, Bicarbonate

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BIOL 3070

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Lecture 9, jan 25 continuation of pdf8
o Carbon dioxide transport:
1) Easily transported in the blood in its dissolved form, 5-7% dissolved in the
2) Bound to Hb (mammalian) not with the association with the heme group 20-
23% of all CO2
Absent in fish
3) Bicarbonate (HCO3-) ions as 70% in mammals
More solube in the blood than CO2
CO2 + H2O  H2CO3 H+ + HCO3-
Carbonic anhydrase responsible for facilitating the rxn of CO2 and H2O
o I fish they do’t have o 2, thus they trasport the CO2 through iarbonate 93%
o CO2 transport during internal respiration:
It will have a gradient that will allow it move from the cells to the capillaries
The capillaries are usually high with O2 and low with CO2
This means that the cells have a high concentration of CO2 and the blood at the
capillaries have low CO2
o The blood leaving the capillaries from the systemic tissue will have a PO2 equal to that
of the tissue so it wont diffuse
Venous capillaries leaving the capillaries:
o PCO2 will have around 46 mmHg at rest and higher during exercise
Gas exchange at tissues internal respiration:
o CO2 is dissolved in plasma
o CO2 binds to hemoglobin (20-25%) in mammals
o Converted in the RBC from CO2 to HCO3
HCO3 would be transported out using an anion exchanger chloride shift
The anion exchanger is used to removed the excess of bicarbonate to further
allow the RBC to change the CO2 to HCO3
o The H+ would then associate with the Hb (it can be any protein) but here with Hb
eause it’s the ost audat.
o This way the PCO2 in the blood is lowered and thus the gradient of CO2 is lowered that
facilitates further removel of CO2 from the systemic cells.
Haldane effect:
o Works with Bohr effect that helps unloads O2 from hemoglobin
o Haldane Effect is when CO2 is picked up by Hb
External Respiration:
o The concentration gradient in the alveoli is the opposite to that found in the systemic
system tissue
o The O2 will diffuse from higher gradient (alveoli) to lower gradient (pulmonary blood)
o CO2 will diffuse from the higher gradient (pulmonary blood) to lower gradient (alveoli)
Hemoglobin will also mop up the free dissolved oxygen which would lower the oxygen gradient
that would drive more oxygen into the blood
Diffusion of O2 at alveolus pulmonary capillary boundary:
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o When the pulmonary blood reaches about 1/3 of the alveolar space, it will be fully
oxygenated (40 mmHg to 104 mmHg) which is when both (pulmonary and alveolar
space) gradients would be in equilibrium 104 mmHg
Diffusion of CO2 at alveolus pulmonary capillary boundary:
o About third of the way, the CO2 would be in equilibrium at from 45 mmHg to 40 mmHg
Gas exchange at lungs:
o CO2:
The dissolved CO2 in the blood is lost first to the alveolar space which would
allow more CO2 to be unloaded from Hb
o O2:
Now the Hb can bind to O2 and also they release H+
o The protons would be bound to HCO- H2CO3
The HCO3- would move from the plasma to the RBC ( reverse chloride shift) the
RBC release Chloride for each bicarbonate.
Lecture 9 pdf:
Slide 1:
o Fresh water teleos they have to release a diluted urine in order to preserve the ions
The major ions are Na+ and Cl-
o The fish is living in a hypotonic environment
They need to take ions from the environment
o The excess water taken up by the fish would be dumped in order to preserve the ions
Slide 3:
o The RBC-gill epithelium gas exchange:
Inability of Hb to bind to CO2 in fish
Bicarbonate is more imp in fish than in mammals
Same as mammals, first, the dissolved CO2 which leads to further removal
of CO2 from the blood
Bicarbonate would be moving into the RBC with Cl moving out
And then the bicarbonate would move out as CO2
Hb would pick up O2 and releases the H+
In gill epithelium:
o Some CO2 would change back to bicarbonate
o H+ would be pumped out through
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