Cardiac pacemaker heart. There are 3 main stages in the generation of an action potential in a pacemaker cell. Since the stages are analogous to contraction of cardiac muscle cells, they have the same naming system. This can lead to some confusion. There is no phase 1 or 2, just phases 0, 3, and 4. The key to the rhythmic firing of pacemaker cells is that, unlike other neurons in the body, these cells will slowly depolarize by themselves and do not need any outside innervation from the autonomic nervous system to fire action potentials. As in all other cells, the resting
Heart rate monitor sensors and these are still the default used for medical devices. The newer technology is based on optical sensors. ECG (Electrocardiography) sensors measure the bio-potential generated by electrical signals that control the expansion and contraction of heart chambers. PPG (Photoplethysmography) sensors use a light-based technology to sense the rate of blood flow as controlled by the heart's pumping action. The electrical monitors consist of two elements: a monitor/transmitter, which is worn on a chest strap, and a receiver. When a heartbeat is detected a radio signal is transmitted, which the receiver uses to display/determine the current heart rate. This signal