Alpha-2 adrenergic receptors are a type of protein found on the surface of certain cells in the body. They play a crucial role in the nervous system by regulating the release of neurotransmitters, which are chemicals that transmit signals between nerve cells. When activated, these receptors can inhibit the release of norepinephrine, leading to a calming effect on the body. These receptors are involved in various physiological processes, including blood pressure regulation and sedation. They are also targets for certain medications, such as clonidine, which is used to treat high blood pressure and attention deficit hyperactivity disorder (ADHD).