Sinoatrial node of the next action potential. Pacemaker cells, however, don’t have this resting phase. Instead, immediately after one action potential, the membrane potential of these cells begins to depolarise again automatically, this is known as the pacemaker potential. Once the pacemaker potential reaches a set value, known as the threshold value, it then produces an action potential. Other cells within the heart (including the purkinje fibers and atrioventricular node; AVN) can also initiate action potentials; however, they do so at a slower rate and therefore, if the SA node is working, it usually beats the AVN to it. Outlined below are
Node B frequency transmitter(s) and the receiver(s) used to communicate directly with mobile devices, which move freely around it. In this type of cellular network, the mobile devices cannot communicate directly with each other but have to communicate with the NodeB. Traditionally, the Node Bs have minimum functionality, and are controlled by an RNC (Radio Network Controller). However, this is changing with the emergence of High Speed Downlink Packet Access (HSDPA), where some logic (e.g., retransmission) is handled on the Node B for lower response times. The utilization of WCDMA technology allows cells belonging to the same or different Node Bs and