AIIMS 2011
- Exam
- AIIMS
- Year
- 2011
- Subject
- Zoology
- Chapter
- Body Fluids and Circulation
AIIMS 2011 · Zoology · Body Fluids and Circulation
Assertion: S.A. node induces excitatory impulses in heart. Reason :...
Assertion: S.A. node induces excitatory impulses in heart.
Reason : S.A. node is self excitatory.
Options
- AIf both assertion and reason are true and reason is the correct explanation of assertion
- BIf both assertion and reason are true but reason is not the correct explanation of assertion
- CIf assertion is true but reason is false
- DIf both assertion and reason are false.
Correct answer
B. If both assertion and reason are true but reason is not the correct explanation of assertion
Step-by-step solution
\sin u-auricular node or S-A node is located in the wall of the right auricle below the opening of the superior vena cava. The S-A node has unique property of self excitation, which enables it to act the "pacemaker" of the heart. It spontaneously initiates a wave of contraction which spreads over both the auricles more or less simultaneously along the muscle fibres that fan out from the pacemaker.