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The pacemaker current (I f, or I Kf, also called funny current) is an electric current in the heart that flows through the HCN channel or pacemaker channel. Such channels are important parts of the electrical conduction system of the heart and form a component of the natural pacemaker .
A slow heart rate of 60 or less beats per minute is defined as bradycardia. A fast heart rate of more than 100 beats per minute is defined as tachycardia. An arrhythmia is defined as one that is not physiological such as the lowered heart rate that a trained athlete may naturally have developed; the resting heart rates may be less than 60 bpm.
In the pacemaking cells of the heart (e.g., the sinoatrial node), the pacemaker potential (also called the pacemaker current) is the slow, positive increase in voltage across the cell's membrane (the membrane potential) that occurs between the end of one action potential and the beginning of the next action potential.
HCN4 is the main isoform expressed in the sinoatrial node, but low levels of HCN1 and HCN2 have also been reported.The current through HCN channels, called the pacemaker current (I f), plays a key role in the generation and modulation of cardiac rhythmicity, [13] as they are responsible for the spontaneous depolarization in pacemaker action potentials in the heart.
This outward flow of potassium ions at the more positive membrane potentials means that the K ir can also aid the final stages of repolarisation. [36] [37] The voltage-gated potassium channels (K v) are activated by depolarization. The currents produced by these channels include the transient out potassium current I to1. This current has two ...
However, in pacemaker cells, this potassium permeability (efflux) decreases as time goes on, causing a slow depolarization. In addition, there is a slow, continuous inward flow of sodium, called the "funny" or pacemaker current. These two relative ion concentration changes slowly depolarize (make more positive) the inside membrane potential ...
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.
The cardiac transient outward potassium current (referred to as I to1 or I to [1]) is one of the ion currents across the cell membrane of heart muscle cells. It is the main contributing current during the repolarizing phase 1 of the cardiac action potential .
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related to: heart current flow- 262 Neil Avenue # 430, Columbus, Ohio · Directions · (614) 221-7464
