Where does respiratory rhythm originate?
For most normal individuals the hypothalmus is is the origin of
central chemoreceptors. These chemoreceptors are very sinsitive to
elevation or drops in pH (or amount of free Hydrogen Ion in the
blood). The equation: H + HCO2 = H2O + CO2
Shows how CO2 in the bloodstreem effects the amount of free H
ion in the blood; in other word the more CO2 in the blood the more
acidic it is and has a lower pH. The lower the pH of the blood is
the more stimulation is given to the central chemoreceptors in the
hypothalmus thus stimulating the phrenic nerve among others to
raise the respiratory rate and blow off the excess CO2.
This process is very different for individuals who are suffering
from chronic CO2 retention (Like in COPD). These indeviduals can
not use the central chemoreceptors due to the excessive CO2 in the
blood is a norm for them! These individuals must now depend on
their peripheral chemoreceptor located through out their body.
These peripheral chemoreceptors are sensitive to O2 levels in the
blood, and are sitmulated by a drop in O2 concentration. This is
why it could be dangerous to give excessive supplimental oxygen to
a person with COPD. If there is no drop in O2 levels (because your
giving them O2) in their blood what stimulates them to breath?
Nothing !!!!! Scary huh? Dont smoke!!!