Search results
Results from the WOW.Com Content Network
In a healthy heart all activities and rests during each individual cardiac cycle, or heartbeat, are initiated and orchestrated by signals of the heart's electrical conduction system, which is the "wiring" of the heart that carries electrical impulses throughout the body of cardiomyocytes, the specialized muscle cells of the heart.
Electrical waves track a systole (a contraction) of the heart. The end-point of the P wave depolarization is the start-point of the atrial stage of systole. The ventricular stage of systole begins at the R peak of the QRS wave complex; the T wave indicates the end of ventricular contraction, after which ventricular relaxation (ventricular diastole) begins.
[1] [2] In the Wiggers diagram, the X-axis is used to plot time subdivided into the cardiac phases, while the Y-axis typically contains the following on a single grid: Blood pressure. Aortic pressure; Ventricular pressure; Atrial pressure; Ventricular volume; Electrocardiogram; Arterial flow (optional) Heart sounds (optional)
The isovolumetric contraction phase lasts about 0.05 seconds, [1] but this short period of time is enough to build up a sufficiently high pressure that eventually overcomes that of the aorta and the pulmonary artery upon opening of the semilunar valves. This process, therefore, helps maintain the correct unidirectional flow of blood through the ...
Consequently, this initial phase of ventricular systole is known as isovolumic contraction, also called isovolumetric contraction. [1] In the second phase of ventricular systole, the ventricular ejection phase, the contraction of the ventricular muscle has raised the pressure within the ventricle to the point that it is greater than the ...
These signals are generated rhythmically, which results in the coordinated rhythmic contraction and relaxation of the heart. On the microscopic level, the wave of depolarization propagates to adjacent cells via gap junctions located on the intercalated disc. The heart is a functional syncytium as opposed to a skeletal muscle syncytium. In a ...
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
In a normal heart, the heart rate is the rate at which the sinoatrial node depolarizes since it is the source of depolarization of the heart. Heart rate, like other vital signs such as blood pressure and respiratory rate, change with age. In adults, a normal heart rate is between 60 and 100 bpm (normocardic), whereas it is higher in children. [56]