Chemoreceptors act most importantly to detect variation of the oxygen in the arterial blood, in addition to detecting arterial carbon dioxide and pH.
These nodes, called the aortic body and carotid body, are located on the arch of the aorta and on the common carotid artery, respectively and send information to the control centre in the medulla of the brain.
Chemoreceptors detect the levels of carbon dioxide in the blood. To do this, they monitor the concentration of hydrogen ions in the blood, which decreases the pH of the blood. This is a direct consequence of an increase in carbon dioxide concentration, because carbon dioxide becomes carbonic acid in an aqueous environment.
The response to increased CO2 is that the respiratory centre (in the medulla), sends nervous impulses to the external intercostal muscles and the diaphragm, via the intercostal nerve and the phrenic nerve, respectively, to increase breathing rate and the volume of the lungs during inhalation.Respiratory rate is influenced by almost everything, anatomically and environmentally. Anatomical causes of respiratory rate changes are ailments such as copd (chronic obstructive pulmonary disease) asthma, airway obstructions, diabetic coma or shock, congestive heart failure (back up of fluids through the venus supply), croup, anaphylaxsis, etc.
Environmental causes include airway anomallies, drug overdoses, inhaled poisons,smoking etc.