Purinergic receptors are a type of cell surface 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 classified into two main types: P1 receptors, which primarily respond to adenosine, and P2 receptors, which respond to ATP and other nucleotides. These receptors are found in many tissues throughout the body, including the brain, heart, and immune system. When activated, purinergic receptors can influence a range of functions, such as regulating blood flow, modulating pain, and controlling immune responses. Their diverse roles make them important targets for research in areas like pharmacology and disease treatment.