Cardiac pacemaker ventricles, within the atrial septum. If the AV node also fails, Purkinje fibers are occasionally capable of acting as the default or "escape" pacemaker. The reason Purkinje cells do not normally control the heart rate is that they generate action potentials at a lower frequency than the AV or SA nodes. Cardiac pacemaker The contraction of cardiac muscle (heart muscle) in all animals is initiated by electrical impulses known as action potentials. The rate at which these impulses fire controls the rate of cardiac contraction, that is, the heart rate. The cells that create these rhythmic impulses, setting the pace
Cardiac neural crest cells of heart attacks include cardiac arrhythmias and heart failure. Although CNCCs are important in embryos, some CNCCs are retained in a dormant state to adulthood where they are called "neural crest stem cells". In 2005, Tomita transplanted neural crest stem cells from mammal hearts to the neural crest of chick embryos. These CNCCs were shown to migrate into the developing heart of the chick using the same dorsolateral pathway as the CNCCs, and differentiate into neural and glial cells. Tamura's study of 2011 examined the fate of CNCCs after a heart attack (myocardial infarction) in young mice. The CNCCs in