Which of the following describes the action of Epinephrine on beta-2 receptors?

Epinephrine primarily acts on beta-2 adrenergic receptors, which are predominantly found in the smooth muscles of the airways. When epinephrine binds to these receptors, it induces relaxation of the bronchial smooth muscle, leading to bronchodilation. This action is particularly important in the treatment of conditions such as asthma or anaphylactic shock, where airway constriction can impede breathing.

The other choices do not align with the known pharmacological effects of epinephrine. Increased gastrointestinal motility, inhibition of lipolysis, and decreased heart rate are not associated with beta-2 receptor activation. In fact, epinephrine is known to decrease gastrointestinal motility and increase lipolysis through different mechanisms, while its action on heart rate typically involves beta-1 receptors, leading to increased heart rate, not a decrease. Therefore, bronchodilation is the direct and correct action of epinephrine on beta-2 receptors.