Carotid bodies are small clusters of chemoreceptor cells located near the bifurcation of the common carotid arteries in the neck. They play a crucial role in monitoring the levels of oxygen and carbon dioxide in the blood, helping to regulate breathing and maintain proper blood gas levels. When oxygen levels drop or carbon dioxide levels rise, the carotid bodies send signals to the brain to adjust respiratory rates. This response helps ensure that the body receives enough oxygen and removes excess carbon dioxide, which is vital for maintaining overall health and proper organ function.