Why is pacemaker current called Funny current?
It is called “funny” because it has effects opposite to those of most other heart currents. If is a mixed Na+–K+ inward current activated by hyperpolarization and modulated by the autonomic nervous system. It is one of the most important ionic currents for regulating pacemaker activity in the sinoatrial (SA) node.
How is action potential produced in the heart?
The cardiac action potential is a brief change in voltage (membrane potential) across the cell membrane of heart cells. This is caused by the movement of charged atoms (called ions) between the inside and outside of the cell, through proteins called ion channels.
Are Funny channels ligand gated?
For example, when an action potential is elicited in a cardiomyocyte, sodium channels transiently open and potassium channels close, which leads to depolarization….Ion Channels.
| CHANNEL | CHARACTERISTICS |
|---|---|
| Slow Na+ | “Funny” pacemaker current (If) in cardiac nodal tissue |
| Potassium Channels |
What happens in a neuron when it becomes hyperpolarized?
Hyperpolarization is a change in a cell’s membrane potential that makes it more negative. It is the opposite of a depolarization. While hyperpolarized, the neuron is in a refractory period that lasts roughly 2 milliseconds, during which the neuron is unable to generate subsequent action potentials.
What is funny current in cardiac pacemaker?
First described in the late 1970s in Purkinje fibers and sinoatrial myocytes, the cardiac pacemaker “funny” (I f) current has been extensively characterized and its role in cardiac pacemaking has been investigated.
What is the action potential of pacemaker cell?
Action potential of the pacemaker cell is different from that of ventricular myocardial cell. It is characterized by lower slope of phase 0 (lower Vmax) and the presence of diastolic depolarization mediated by the funny current (I f ), also known as pacemaker current.
What is the difference between cardiac action potential and electrocardiogram?
It may be noted that the cardiac action potential is different from the surface electrocardiogram which represent the sum total of all electrical activity of the heart as recorded from the body surface. Myocardial action potential is recorded with intracellular electrode under experimental conditions.
What are the phases of myocardial action potential?
Myocardial action potential is recorded with intracellular electrode under experimental conditions. The action potential has a total of 5 phases. Phase 0 (Rapid depolarization): Phase 0 is the initial phase of rapid depolarization in which the intracellular voltage rises from about -90mV to about +20 mV. The peak rate of rise is called V max.