Electrical Initiation
The heartbeat begins in the sinoatrial node (SA node), the heart's natural pacemaker located in the right atrium. This specialized tissue generates electrical impulses that trigger each heartbeat. The electrical signal spreads through the atria, causing them to contract and push blood into the ventricles. The signal then travels through the atrioventricular node (AV node), which briefly delays the impulse to allow proper chamber filling.
Muscle Contraction
After passing through the AV node, the electrical signal travels along specialized pathways called bundle branches and Purkinje fibers, spreading throughout the ventricle walls. This coordinated electrical activity causes the ventricles to contract powerfully, pushing blood out to the lungs and body. The left ventricle generates higher pressure to pump blood throughout the entire body, while the right ventricle sends blood to the lungs for oxygenation.
Rhythm Regulation
The heart's rhythm adjusts constantly to meet the body's changing needs. The autonomic nervous system influences heart rate, with sympathetic stimulation increasing rate during exercise or stress, and parasympathetic activity slowing it during rest. Hormones, blood chemistry, and blood pressure also affect heart rhythm. This complex regulation ensures adequate blood flow under varying conditions.Shutdown123