Neural oscillation sinoatrial node normally initiates it, simply because it generates impulses slightly faster than the other areas. Hence, these cells generate the normal sinus rhythm and are called pacemaker cells as they directly control the heart rate. In the absence of extrinsic neural and hormonal control, cells in the SA node will rhythmically discharge. The sinoatrial node is richly innervated by the autonomic nervous system, which up or down regulates the spontaneous firing frequency of the pacemaker cells. Synchronized firing of neurons also forms the basis of periodic motor commands for rhythmic movements. These rhythmic outputs are produced by a group
Sinoatrial node the 3 phases of a sinoatrial node action potential. In the ventricular action potential, there are 5 phases (labelled 0-4), however pacemaker action potentials don’t have an obvious phase 1 or 2. Phase 4 This phase is also known as the pacemaker potential. Immediately following an action potential, when the membrane potential is very negative (it is hyperpolarised) the voltage slowly begins to increase. This is initially due to the closing of potassium channels, which reduces the flow of potassium ions (I) out of the cell (see phase 3, below). Alongside the deactivation of the potassium channels, channels known as