Regulation of respiration

[Nicholas Cheong]

I was confused when I read regulation of respiration by the brain.

Are there any free H+ sensors in the brain? I understand that
H+ ions cannot readily cross the BBB and only CO2 can do so.
CO2 subsequently reacts with water, forming carbonic acid which later
dissociates into H+ and bicarbonate.

My confusion arose when i read some
other texts which stated that H+ ions have direct effect on the
respiratory centers. Understanding the regulation of respiration
is of great importance to me.

Thank you,

N Mak

Edited by
Nicholas Cheong
MBBS Batch 14

[Nicholas Cheong]

Dear N Mak,

There are sensors that readily detect changes in H+ concentration in
the brain ECF. These are called central chemoreceptors and are
situated in the brainstem. It is not known in which part of the
brainstem these receptors reside. Nevertheless, they are widely
dispersed in the brainstem. I believe you are right in saying that
only CO2 can cross the blood brain barrier.

In a way, one can say that H+ exerts a direct effect on the central
chemoreceptors because ventilatory changes to elevated PaCO2 is
mediated by a drop in pH of brain ECF (higher H+ concentration).
Although, H+ does not cross BBB, CO2 traverses BBB and becomes
hydrated. H+ is ultimately formed (as you mentioned).

Hope this helps.

Best,

Nicholas Cheong
MBBS Batch 14

On Sep 29, 1:53 pm, Nicholas Cheong <nicholascheon...@gmail.com>
wrote: