The physiology instructor explains to the nursing students that beta-2 stimulation leads to:

increase in the diameter of the bronchioles leading to increase in the amount of air that can be let in and out during breathing and dilation of the vessels of skeletal muscles to account for the increased blood flow.

Explanation:

Beta receptors are a class of cell receptors present on the cell surface and tissues of effector organs and tissues innervated by the sympathetic nervous system and mediate certain physiological response when bounded by certain adrenergic agents.

Beta 2 receptors are those receptors that bind with epinephrine, a hormone and neurotransmitter (adrenaline) whose signaling mediate physiological response like smooth muscle relaxation and bronchodilation.