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Tamil Nadu Board of Secondary EducationHSC Science Class 11

What are the heart sounds? When and how are these sounds produced? - Zoology

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Question

What are the heart sounds? When and how are these sounds produced?

Answer in Brief

Solution

  1. Rhythmic contraction and expansion of heart is called heart beat. The contraction of the heart is called systole and the relaxation of the heart is called diastole. The heart normally beats 70-72 times per minute in a human adult. During each cardiac cycle two sounds are produced that can be heard through a stethoscope.

  2. The first heart sound (lub) is associated with the closure of the tricuspid and bicuspid valves whereas Second heart sound (dub) is associated with the closure of the semilunar valves. These sounds are of clinical diagnostic significance. An increased heart rate is called tachycardia and decreased heart rate is called bradycardia.

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Chapter 7: Body Fluids and Circulation - Evaluation [Page 133]

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Samacheer Kalvi Zoology [English] Class 11 TN Board
Chapter 7 Body Fluids and Circulation
Evaluation | Q 22. | Page 133
Samacheer Kalvi Biology (Zoology) [English] Class 11 TN Board
Chapter 7 Body Fluids and Circulation
Evaluation | Q 23. | Page 129

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