Bohr effect and chloride shift

What happens when cells respire?

CO₂ is released, which raises pCO₂ and increases rate of oxygen dissociation from oxyhemoglobin

What happens to most of the CO2 produced?

Diffuses into RBC and is converted into carbonic acid by carbonic anhydrase

What happens to the rest of the CO2?

Binds to haemoglobin (carbominohaemoglobin) and is carried to the lungs

What does carbonic acid dissociate into?

H+ ions and HCO₃^- (hydrogencarbonate) ions

What does the increase in H+ ions do?

Causes oxyhemoglobin to unload the O₂ so that haemoglobin can take up the H+ ions, which forms haemoglobin acid preventing H+ ions from lowering RBC pH

What happens to hydrogen carbonate ions?

Diffuse out of RBCs and into blood plasma where they are transported back to the lungs

What happens in the lungs?

Low pO₂ in the lungs, so the H+ and hydrogencarbonate ions recombine to form CO₂

What are hydrogencarbonate ions very soluble in?

Blood plasma (unlike CO₂), so they return to blood plasma by moving out the RBC

What do the hydrogencarbonate ions move across?

A special ion-exchange membrane protein, then a chloride ion is brought into the cell

Why does the chloride shift take place?

To maintain neutrality so there is little change in pH