Where does the cardiac impulse originate?

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(a)

The cardiac impulse originates in cardiac muscle fibres and is not brought to the heart by any nerve fibres. The origin of cardiac impulse is said to be myogenic.

Sinoatrial node is called the pacemaker of our heart. Why?

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(a)

Sinoatrial node of heart is responsible for initiating and maintaining the rhythmic activity, therefore it is known as pacemaker of the heart?

List the location of each of the valves of the heart.

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(a)

The tricuspid valves are present between right atrium and ventricle.Bicuspid valves are between the wall of left atrium and left ventricle. The semilunar valves are present in the inner wall of aorta.

Define systole and diastole.

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(a)

Contraction of heart muscles brings right and left atria at systole and relaxation of heart muscles brings them at diastole.

Given below is the diagrammatic representation of a standard ECG. Label its different peaks.

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(a)

The representation of a standard ECG diagram