Final answer:
Peripheral chemoreceptors in the aortic arch and carotid arteries trigger increased respiratory activity when they detect abnormally low blood oxygen levels, thereby ensuring the body maintains sufficient oxygen delivery to tissues.
Step-by-step explanation:
If peripheral chemoreceptors detect abnormally low levels of dissolved oxygen (PO₂) in the blood, roughly at or below 60 mm Hg, they trigger a response to increase respiratory activity. This occurs because the peripheral chemoreceptors, located in the aortic arch and carotid arteries, can only sense the levels of oxygen that are not bound to hemoglobin. Therefore, the detection of low oxygen levels stimulates the chemoreceptors to activate the respiratory control centers, which results in an increase in the rate and depth of breathing to enhance oxygen intake and improve oxygenation of the blood.
The body has two sets of chemoreceptors that play roles in regulating the respiratory and cardiovascular systems based on the levels of carbon dioxide, hydrogen ions, and oxygen. These systems work together to ensure adequate oxygen supply to tissues and the removal of carbon dioxide and other waste products. When peripheral chemoreceptors signal a decrease in oxygen levels, it prompts a cascade of events to boost breathing and maintain the body's homeostasis.