Question

Which of the following leads to negligible or no stimulation of receptors located in the aortic arch and carotid artery?

• A. High oxygen concentration
• B. Low carbon dioxide concentration
• C. Low pH
• D. None of the above

Answer 1

The correct option is A High oxygen concentration

Receptors (chemoreceptors) associated with the aortic arch and carotid artery are called the aortic body and carotid body respectively. The carotid bodies are located on the bifurcation of one of the main arteries of the neck called the carotid artery. Whereas, the aortic body is located on the aortic arch, which is the portion of the main artery (aorta) that bends between the ascending and descending part of the aorta. The aortic body and the carotid body can recognise changes in carbon dioxide and hydrogen ion concentration in the blood and send necessary signals to the respiratory rhythm centre for remedial actions. If the carbon dioxide concentration is high or pH is low, these chemoreceptors detect it. These signals are transmitted to the medullary respiratory centre (present in hindbrain). The respiratory centre then directs the respiratory muscles like external intercostal muscles and diaphragm to help increase the breathing rate. Oxygen concentrations are not generally detected by these chemoreceptors.