Heart Rate Lowering Drug: Ivabradine - Thesis Example

A sophisticated strategy for comprehension of pacemaker initiation and propagation had to bid time for centuries, right up until the revealing of the bundle linking atrium and ventricle by Wilhelm His, the atrioventricular node by Sunao Tawara, and the sinoatrial node by Arthur Keith and Martin Flack in the later part of the nineteenth to the beginning of the twentieth century together with the advancement of electrophysiological strategies. Today it is clearly recognized that the sinoatrial node (SAN) to be the biological pacemaker region of the heart.

In contrast to force providing tissue of the functioning muscle, whose primary task is mechanical, sinoatrial myocytes hold the unique attribute of self-generating repetitive action potentials but show an inadequately established contractile system; their principal purpose is electric, not mechanical. The sinoatrial node (SAN) is an incredibly unique structure found within wall of the right atrium, their impulsive action potentials pass on, via unique conduction systems, initially towards the atria there-after towards the ventricles, thereby creating heart rhythmic contractions and setting the heart rate.

The control of heart rate is without a doubt an activity of significant physiological importance, and it is truly not unexpected that the recognition of the exact electrical functions underpinning the pacemaker action is bound to have drawn the ceaseless attention of cardiac physiologists. Typically the heart cells of the atrial and ventricular lay at a hyperpolarized voltage level throughout the period of diastole which corresponds to the period in which the heart muscle is in a relaxed form.

Automatically beating SAN myocytes, on the other hand, seem to be distinguished by the occurrence of a slow diastolic depolarization phase, which means that their membrane voltage will never keep still at a negative level at the end of the action potential, on the contrary it gradually seeps up with a roughly steady slope, right up until it attains the threshold for a new SAN action potential (DiFrancesco, 1993). The pacemaker function located atrium determines the heart rate (HR). Diastolic depolarization causes instantaneous electrical impulse of SAN cells.

The slow diastolic pacemaker depolarization thus accounts for the creation of repetitive action potential; as a result it has turned into the main objective of rigorous scientific studies geared towards the knowledge of the cellular mechanisms which create it. Despite the fact that the cellular steps contributing towards the pacemaker depolarization are several, and their particular participation remains an issue of exploration (DiFrancesco, 2002). Beta-modulation of pacemaker rate: novel mechanism or novel mechanics of an old one?

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