The Normal Heart
How Does the Normal Heart Beat?
The heart is a muscular pump that beats 60 to 100 times every minute to transmit blood throughout the body. Each heartbeat is triggered by an electrical impulse, which travels through a network of electrical wires, the heart's conduction system.
The impulse starts in the sino-atrial node (SA Node), the natural pacemaker of the heart.
It travels through the right and left atria (upper chambers) to the atrioventricular node (AV node). Contraction of the atria results in forward flow of blood to the ventricles (lower chambers).
The AV Node functions as the electrical "junction box" of the heart. After a slight delay in the AV node, the impulse goes through the bundle of His, the right and left bundle branches, and the Purkinje fibers, to the muscles of the right and left ventricles (lower chambers). Simultaneous and coordinated contraction of the ventricles pumps blood to the rest of the body.
The SA Node, AV Node, bundle of His, bundle branches, and the Purkinje fibers together constitute the heart's conduction system.
Normal functioning of the heart is dependent on the appropriate:
Any abnormality can result in fast, slow, or disorganized contraction of the heart and decreased blood supply to vital organs of the body. These conditions are collectively referred to as "arrhythmias".
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