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Medical Dictionary

pacemaker

Pronunciation (pās′māk-ĕr)
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  1. Biologically, any rhythmic center that establishes a pace of activity.
  2. An artificial regulator of rate activity.
  3. In chemistry, the substance of which the rate of reaction sets the pace for a series of chain reactions; the rate-limiting reaction itself, e.g., in a metabolic pathway, the enzyme catalyzing the slowest or rate-limiting reaction in that pathway.

[L. passus, step, pace]

WebMD Medical Reference from "Stedman's Medical Dictionary"

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