What are beta blockers and how do they work? Beta blockers, also known as beta-adrenergic blocking agents, are a class of drugs that works by blocking the neurotransmitters norepinephrine and epinephrine from binding to receptors. There are three known types of beta receptors, known as beta1 (Î²1), beta2 (Î²2) and beta3 (Î²3).
Although many newer imaging techniques for the evaluation of lung pathology have been developed, auscultation of the chest remains an invaluable clinical tool and is still probably the most common method of evaluating the lung. Evaluation of lung sounds is a routine part of a clinical examination. Breath sounds can be classified into 2 broad categories: normal breath sounds and adventitious (or abnormal) sounds. Adventitious breath sounds include wheezes, coarse crackles, fine crackles, and rhonchi. See the video of breath sound assessment, below.
Adventitious: Coming from an external source or occurring in an unusual place or manner. Not inherent, inherited or innate but rather occurring accidentally or spontaneously. When a doctor or nurse auscults (listens to) the chest or abdomen, adventitious sounds are those that are normally not heard coming from the chest or abdomen. The word adventitious comes from the Latin adventicius meaning foreign, strange, extraneous, coming from abroad or from outside.. This, in turn, comes from the verb advenire meaning to come to or to arrive..