lub

(noun)

The first heart tone, or S1,  caused by the closure of the atrioventricular valves (mitral and tricuspid) at the beginning of ventricular contraction or systole.

Related Terms

  • Heart murmurs
  • dub

Examples of lub in the following topics:

  • Heart Sounds

    • The two major heart sounds are "lub" (from the closure of AV valves) and "dub: (from the closure of aortic and pulmonary valves).
    • This sound may be described as either a "lub" or a "dub" sound.
    • The first heart sound, called S1, makes a "lub" sound caused by the closure of the mitral and tricuspid valves as ventricular systole begins.
    • S3 makes a "ta" sound after the "lub-dub" while S4 makes a "ta" sound before the "lub-dub".
    • The closing of the heart valves generates the "lub, dub" sounds that can be heard though a stethoscope.
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