Mo' Beta

I occasionally hear references to 'beta blockers' as a class of drugs, but I don't really understand what they are. This morning, I was reading an article on the subject and thought 'dammit, what are these things?'

From the magic of Google and Medterms.Com --

A class of drugs that block beta-adrenergic substances such as adrenaline (epinephrine) in the "sympathetic" portion of the autonomic (involuntary) nervous system. By blocking the action of the sympathetic nervous system on the heart, beta blockers relieve stress on the heart; they slow the heart beat, lessen the force with which the heart muscle contracts, and reduce blood vessel contraction in the heart, brain, and throughout the body. Beta blockers may be used to treat abnormal heart rhythms (cardiac arrhythmias) and prevent abnormally fast heart rates (tachycardias) or irregular heart rhythms such as premature ventricular beats.

I think it is so neat that there are drugs whose benefit is that they prevent normal functioning....