Beta-2 refers to a type of adrenergic receptor found in various tissues throughout the body. These receptors play a crucial role in the sympathetic nervous system, which is responsible for the body's "fight or flight" response. When activated, beta-2 receptors help to relax smooth muscles, particularly in the airways, making them important for respiratory function. In medicine, beta-2 agonists are commonly used as bronchodilators to treat conditions like asthma and chronic obstructive pulmonary disease (COPD). By stimulating beta-2 receptors, these medications help to open up the airways, improving airflow and making it easier for patients to breathe.