Nervous system 5, Neuromuscular junction

There is a wide range of chemical transmitter molecules used in the nervous system. Two common transmitters are acetylcholine and noradrenalin (also called norepinephrine). Acetylcholine is also the neuromuscular transmitter molecule used at the neuromuscular junctions. Once any chemical transmitter has activated the post synaptic membrane it must be removed from the synaptic gap. If this is not done there will be continued stimulation of the receptor sites. Some of the transmitter simply diffuses away into the tissue fluid. However, some is actively reabsorbed by the pre-synaptic neurone for recycling. In addition, in the case of acetylcholine, the molecule is broken down and inactivated by a tissue enzyme called acetylcholinesterase.