Question: where are the chemo-receptors that monitor blood levels of o2 co2 & h+ located

title: Peripheral chemoreceptors
text: Transferring the signal to the medulla requires that neurotransmitter be released from the vesicles in the type I cells , and as with many other neural cells , this is triggered by an influx of calcium into the cell after membrane depolarization . The process of identifying signal transduction in interoceptors such as the peripheral chemoreceptors requires moving backward from membrane depolarization to discover the previous steps , often internal to the cell , that transduces blood chemicals to a neural signal . Up to this point , most research agrees that membrane depolarization is caused by inhibition of potassium channels that otherwise maintain the resting potential . As to the step before potassium channel inhibition , many mechanisms are proposed , none of which receive unanimous support from the research community . Multiple types of potassium channels respond to hypoxia , with significant differences between different species , and a number of different types for each species . Expression of potassium channels also changes throughout the lifetime . Some studies propose that heme - oxygenase 2 is the transducer ; however , since its deletion in mice does not affect chemoreceptor oxygen sensitivity , this hypothesis is open to question . Another enzyme , AMP - activated protein kinase ( AMPK ) , provides a mechanism that could apply not only to all types of potassium channels , but also other oxygen - sensing tissues in the body , such as pulmonary vasculature and neonatal chromaffin cells . AMPK is an enzyme activated by an increase in the AMP : ATP ratio resulting from increasing cellular respiration . Once activated , the enzyme promotes production of ATP and suppresses reactions that consume it . AMPK activation is also a more appealing candidate because it can activate both of the two most common types of potassium channels . Another study identified that AMPK opens and closes potassium channels via phosphorylation , further underlining the link between the two . The role of AMPK in oxygen sensing in type - 1 cells has however also recently been called into question .