Does the medulla monitor blood pH or is it only the receptors in the heart (aorta / carotid bodies)?
Is this a homework question?
no its a me being confused question
you see I have read several different books / sources and they each imply different things
some books imply it only monitors tissue fluid pH (Cerebospinal fluid) some imply it just acts as a co-ordinator and some imply it monitors blood pH
which one is correct ?
It does so indirectly by monitoring CO2 levels. CO2 crosses the BBB freely, which is converted by carbonic anhydrase to H+. in the CSF.
So if there is a rise in CO2 (think ultimately acid here), this will cause the central chemoreceptors to stimulate respiration: leading to you blowing off the acid and decreasing pH.
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