Search results
Results From The WOW.Com Content Network
The slope of phase 0 on the action potential waveform (see figure 2) represents the maximum rate of voltage change of the cardiac action potential and is known as dV/dt max. In pacemaker cells (e.g. sinoatrial node cells), however, the increase in membrane voltage is mainly due to activation of L-type calcium channels.
This is the ejection stage of the cardiac cycle; it is depicted (see circular diagram) as the ventricular systole–first phase followed by the ventricular systole–second phase. [2] After ventricular pressures fall below their peak(s) and below those in the trunks of the aorta and pulmonary arteries, the aortic and pulmonary valves close ...
An action potential (also known as a nerve impulse or "spike" when in a neuron) is a series of quick changes in voltage across a cell membrane. An action potential occurs when the membrane potential of a specific cell rapidly rises and falls. [1] This depolarization then causes adjacent locations to similarly depolarize.
Cardiac physiology or heart function is the study of healthy, unimpaired function of the heart: involving blood flow; myocardium structure; the electrical conduction system of the heart; the cardiac cycle and cardiac output and how these interact and depend on one another.
After initiation of an action potential, the refractory period is defined two ways: The absolute refractory period coincides with nearly the entire duration of the action potential. In neurons, it is caused by the inactivation of the voltage-gated sodium channels that originally opened to depolarize the membrane. These channels remain ...
A Wiggers diagram, named after its developer, Carl Wiggers, is a unique diagram that has been used in teaching cardiac physiology for more than a century. [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 ...
Image of a myocardial action potential. Effective refractory period in green. In electrocardiography, during a cardiac cycle, once an action potential is initiated, there is a period of time that a new action potential cannot be initiated.
With its inactivation gate closed, the channel is said to be inactivated. With the Na + channel no longer contributing to the membrane potential, the potential decreases back to its resting potential as the neuron repolarizes and subsequently hyperpolarizes itself, and this constitutes the falling phase of an action potential. The refractory ...