Does the acidity of blood control the breathing rate?
This is fairly true.
In our bodies we have receptors constantly monitoring the level of
the CO2 in our blood. When the level of CO2 rises, these receptors
(called chemo-receptors) will register this, and signal the
breathing center to increase rate of breathing.
What does this have to do with acidity you ask?
In our blood we have buffer systems, which are designed to minimize
the change in pH done our blood by different waste products of
metabolism. The main buffersystem is called the bicarbonate
CO2 + H2O <----> H2CO3 (carbonic acid) <---> H+ + CO3-
The reaction is catalyzed by the enzyme carbonic anhydrase.
From the above equation you can deduct two things:
a) If you ADD CO2 to the equation, more H+ will eventually be
produced and this will diminish the pH of the blood (pH =
b) If you REMOVE CO2 from the equation, the reverse happens and
less H+ is produced. This will raise the pH of the blood.
This is why the chemoreceptors register blood CO2 levels. Actually,
what they are measuring is the pH of the blood. If they register
too low a pH, they can signal the ventilation center in the brain
to increase breathing, and thereby remove more CO2 from the body,
and raise the pH.
The body uses this to combat conditions in which the pH of the body
is too low. An example of this could be the state of diabetic
ketoacidosis. This condition, not uncommon amongst diabetics, is
characterized by increased acid production and thereby a lower
The body responds to this threat by increasing ventilation
(increased breathing) thereby removing CO2 from the blood and
raising the pH. By these means the condition is compensated.
Normal blood pH ranges are: 7,35 - 7,45.