Human heart, cardiac cycle and ECG
Why this is asked: The SA node generates about 70-75 impulses a minute on its own, faster than any other part of the conduction system, which is exactly why it — not the AV node — is the pacemaker that sets heart rate. On an ECG, the P wave is atrial depolarisation and the T wave is ventricular repolarisation, but atrial repolarisation never gets a wave of its own because it is buried inside the much larger QRS complex.
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Cardiac activities of the heart are regulated by:
A. Nodal tissue
B. A special neural centre in the medulla oblongata
C. Adrenal medullary hormones
D. Adrenal cortical hormones
Choose the correct answer from the options given below:
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Following are the stages of the pathway for conduction of an action potential through the heart:
A. AV bundle · B. Purkinje fibres · C. AV node · D. Bundle branches · E. SA node
Choose the correct sequence of the pathway from the options given below:
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Match List I with List II.
List I List II A. P wave I. Heart muscles are electrically silent B. QRS complex II. Depolarisation of ventricles C. T wave III. Depolarisation of atria D. T–P gap IV. Repolarisation of ventricles Choose the correct answer from the options given below:
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