Sinoatrial node rate, and increasing heart rate. An increase in heart rate is known as positive chronotropy. The parasympathetic nerves supplying the SA node (in particular the Vagus nerves) originate in the brain. These nerves release a neurotransmitter called acetylcholine (ACh). ACh binds to a receptor called an M2 muscarinic receptor, located on the SA node membrane. Activation of this M2 receptor, then activates a protein called a G-protein (in particular G protein, i for inhibitory). Activation of this G-protein, blocks the cAMP pathway, reducing its effects, therefore inhibiting sympathetic activity and slowing action potential production. As well as this, the G-protein
Node B Node B Node B is the telecommunications node in particular mobile communication networks, namely those that adhere to the UMTS standard. The Node B provides the connection between mobile phones (UEs) and the wider telephone network. UMTS is the dominating 3G standard. Node B corresponds to BTS (base transceiver station) in GSM. This is the hardware that is connected to the mobile phone network that communicates directly with mobile handsets. In contrast with GSM base stations, Node B uses WCDMA/TD-SCDMA as the air interface technology. As in all cellular systems, such as UMTS and GSM, the Node B contains radio