Final answer:
Chemoreceptors are the receptors that adjust the respiratory rate in response to changes in blood levels of carbon dioxide, oxygen, and pH. Central chemoreceptors in the medulla oblongata detect pH changes, while peripheral chemoreceptors in the aortic arch and carotid arteries are sensitive to oxygen and carbon dioxide levels.
Step-by-step explanation:
The receptors that modify respiratory rates by responding to the amount of carbon dioxide, oxygen, or acid levels in the blood are known as chemoreceptors. These are divided into two main types: central chemoreceptors, which are located in the medulla oblongata and respond to changes in the pH of cerebrospinal fluid (CSF), and peripheral chemoreceptors, which are found in the aortic arch and carotid arteries and respond to changes in the oxygen and carbon dioxide levels of the blood.
The central chemoreceptors primarily respond to the pH changes that are indicative of carbon dioxide levels in the blood because CO2 is rapidly converted to carbonic acid in the blood, altering the pH. Meanwhile, the peripheral chemoreceptors are sensitive to the levels of dissolved oxygen in the blood, particularly when it falls below a threshold, which is about 60 mm Hg, as well as to changes in carbon dioxide levels. These receptors provide feedback to the respiratory centers in the brain, such as the medulla oblongata, which trigger an increase in the rate and depth of breathing to adjust the blood gas levels and pH to their normal ranges.