Monday, 14 February 2011
Electrical Activity of the Human Heart
The heart is said to be myogenic, in that it is self stimulating. This is due to the cells of the sinoatrial node being designed to release electrical impulses at set intervals. These impulses spread rapidly through the heart muscle cells of the atria using gap junctions, until they reach the non-conducting connective tissues, where a 0.1 second delay occurs. During which, the atria contract, forcing blood into the ventricles and the impulses gather around the atrioventricular node. From here, impulses travel through the bundle of His to the Apex of the heart and then, move upwards and outwards through purkyne tissues, causing the ventricles to contract with force.
The non-conducting connective tissue is vital for causing the delay because it allows the atria to contract before the ventricles, ensuring the one-way flow of blood through the heart.