A baroreceptor is a type of sensory nerve ending that detects changes in blood pressure. These receptors are primarily located in the walls of large blood vessels, such as the carotid arteries and the aorta. When blood pressure rises or falls, baroreceptors send signals to the brain to help regulate heart rate and blood vessel diameter, maintaining stable blood pressure levels. Baroreceptors play a crucial role in the body's autonomic nervous system, which controls involuntary functions. They help initiate reflexes that adjust heart rate and blood vessel constriction, ensuring that organs receive adequate blood flow. This feedback mechanism is essential for overall cardiovascular health.