As you may have already been aware, the various adrengergic drugs at the anesthesiologist's disposal have different selectivity to the types of receptors they bind and stimulate.  We have obtained that knowledge, over time, to determine which agonist is best for the desired effect we wish to achieve. That being said the following diagram below illustrates the various agonists and the receptors they are known to bind to and stimulate. These are noteworthy to memorize. Have I missed any you would include?

As you may recall, the parasympathetic nervous system has a cranial-sacral distribution where as the sympathetic nervous system has a thoraco-lumbar distribution. The sympathetic nervous system secretes the neurotransmitter norepinephrine in the post ganglionic sympathetic nerve fibers. Norepinephrine binds to end-organ adrenergic receptors to exert various effects on the various adrenergic receptors as seen below. It is worth while to remember these actions.  Note: the neurotransmitter of the sympathetic preganglionic nerve fibers is acetylcholine.

Mechanism of action: