Smooth muscle along the trachea and the first few branches of bronchi have beta 2 adrenergic receptors.

气管和初级支气管分支的平滑肌上，都有β2受体。

Going back to that turkey, when you're running, the sympathetic nerves stimulate those beta 2 adrenergic receptors and increase the diameter of the airways.

再来看逃离大鹅的例子：当我们在奔跑时，交感神经系统激动β2受体，使气道扩张，以吸入更多氧气。

Class 2 beta blockers These drugs bind to beta-1 adrenergic receptors and block the sympathetic influences that act through these receptors.

第二类是β受体阻滞剂。这类药物与β-1肾上腺素能受体结合，阻断交感神经作用于这些受体产生的影响。