MUSCLE
CARDIAC MUSCLE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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AV Node
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Bundle of His
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Purkinje fibers
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SA Node
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Detailed explanation-1: -This electrical signal begins in the sinoatrial (SA) node, located at the top of the right atrium. The SA node is sometimes called the heart’s “natural pacemaker.” When an electrical impulse is released from this natural pacemaker, it causes the atria to contract.
Detailed explanation-2: -It is located at the junction of the crista terminalis in the upper wall of the right atrium and the opening of the superior vena cava. These cells have the ability to spontaneous generate an electrical impulse. It is the integrated activity of these so-called pacemaker cells that form the SA node.
Detailed explanation-3: -The SA node is the pacemaker of the heart and has an intrinsic rate of 60 – 100 bpm. If the SA node does not fire, the next pacemaker in hierarchical order is the AV node. This intrinsic rate of the AV node is 40 – 60 bpm.
Detailed explanation-4: -The SA (sinoatrial) node generates an electrical signal that causes the upper heart chambers (atria) to contract. The signal then passes through the AV (atrioventricular) node to the lower heart chambers (ventricles), causing them to contract, or pump. The SA node is considered the pacemaker of the heart.