Beta-adrenergic receptors are a type of protein found on the surface of cells that respond to hormones like epinephrine and norepinephrine. They play a crucial role in the body's response to stress, helping to regulate heart rate, blood pressure, and energy metabolism. There are three main subtypes: beta-1, beta-2, and beta-3, each with specific functions in different tissues. When activated, beta-adrenergic receptors trigger a series of cellular responses through a signaling pathway involving cyclic AMP. This can lead to increased heart contraction strength, relaxation of airway muscles, and breakdown of fat for energy. These receptors are important targets for medications used to treat conditions like asthma and heart disease.