Purinergic receptors are a type of cell receptor that respond to purines, which are organic compounds like adenosine and ATP (adenosine triphosphate). These receptors play a crucial role in various physiological processes, including neurotransmission, inflammation, and cellular signaling. They are found in many tissues throughout the body, allowing cells to communicate and respond to changes in their environment. There are two main classes of purinergic receptors: P1 receptors, which primarily respond to adenosine, and P2 receptors, which respond to ATP and other nucleotides. These receptors are involved in numerous functions, such as regulating blood flow, modulating pain, and influencing immune responses, making them important targets for medical research and drug development.