The term "β2" often refers to the beta-2 adrenergic receptor, a protein found on the surface of certain cells in the body. This receptor plays a crucial role in the sympathetic nervous system, responding to hormones like epinephrine and norepinephrine. When activated, β2 receptors help regulate various physiological processes, including airway dilation in the lungs and the relaxation of smooth muscles. In medicine, β2 agonists are commonly used as bronchodilators to treat conditions such as asthma and chronic obstructive pulmonary disease (COPD). These medications work by stimulating the β2 receptors, leading to the relaxation of airway muscles and improved airflow.