action /ac·tion/ (ak´shun) the accomplishment of an effect, whether mechanical or chemical, or the effect so produced.
ball-valve action,
ball-valve action the intermittent obstruction caused by a free or partially attached foreign body in a tubular or cavitary structure, as by a foreign body in a bronchus, a stone in a bile duct, or a tumor in the cardiac atrium. 
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Ball-valve action. Calculi obstructing the cystic duct (A), common hepatic duct (B), and common bile duct (C) .
cumulative action action of increased intensity, as the sudden and markedly increased action of a drug after administration of several doses, due to the accumulation of the drug in the body.
reflex action a response, often involuntary, resulting from passage of excitation potential from a receptor to a muscle or gland over a reflex arc.
ball-valve action,
the intermittent opening and closing of an orifice by a buoyant, ball-shaped mass, which acts as a valve. Some kinds of objects that may act in this manner are kidney stones, gallstones, and blood clots.
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