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Cardiac excitation-contraction coupling (Cardiac EC coupling) describes the series of events, from the production of an electrical impulse (action potential) to the contraction of muscles in the heart. [1] This process is of vital importance as it allows for the heart to beat in a controlled manner, without the need for conscious input.
Within the muscle tissue of animals and humans, contraction and relaxation of the muscle cells is a highly regulated and rhythmic process.In cardiomyocytes, or cardiac muscle cells, muscular contraction takes place due to movement at a structure referred to as the diad, sometimes spelled "dyad."
Myocardial contractility represents the innate ability of the heart muscle (cardiac muscle or myocardium) to contract.It is the maximum attainable value for the force of contraction of a given heart.
An induction shock produces a contraction or fails to do so according to its strength; if it does so at all, it produces the greatest contraction that can be produced by any strength of stimulus in the condition of the muscle at the time. This principle was later found to be present in skeletal muscle by Keith Lucas in 1909. [1]
Cardiac muscle tissue has autorhythmicity, the unique ability to initiate a cardiac action potential at a fixed rate – spreading the impulse rapidly from cell to cell to trigger the contraction of the entire heart. This autorhythmicity is still modulated by the endocrine and nervous systems. [1]
Cardiac diastole is the period of the cardiac cycle when, after contraction, the heart relaxes and expands while refilling with blood returning from the circulatory system. [ 1 ] [ 2 ] Both atrioventricular (AV) valves open to facilitate the 'unpressurized' flow of blood directly through the atria into both ventricles, where it is collected for ...
Contraction that squeezes blood towards the exit is more efficient than a simple squeeze from all directions. Although the ventricular stimulus originates from the AV node in the wall separating the atria and ventricles, the Bundle of His conducts the signal to the apex. Depolarization propagates through cardiac muscle very rapidly.
First, atrial contraction feeds blood into the ventricles, then ventricular contraction pumps blood out of the heart to the body systems, including the lungs for resupply of oxygen. Cardiac systole is the contraction of the cardiac muscle in response to an electrochemical stimulus to the heart's cells (cardiomyocytes).