The carotid body is a small cluster of chemoreceptors located near the bifurcation of the common carotid artery in the neck. It plays 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 the carotid body detects low oxygen levels, it sends signals to the brain to increase respiratory rate and depth. This response helps ensure that the body receives adequate oxygen, especially during physical activity or in high-altitude environments where oxygen levels may be lower.