• When CO2 is high or low in the blood the stimulus triggers the chemoreceptor. 

• In response talk to the brain stem medulla the respiratory center. 

• In response sympathetic or parasympathetic activation

• The trigger change muscle of breathing or airway of breathing to bring back to homeostasis.

• Hyperventilation releases too much CO2. 

• Low CO2 in blood corresponds to PH value. 

• CO2 converts to bicarbonate and hydrogen ion.

• CO2 level high in blood they quickly convert to more bicarbonate turn out high level of hydrogen ion.CO2 level high low level of PH in blood caused more acidic in blood.