The figure below shows the two main families of acetylcholine receptors: muscarinic and nicotinic. In structural terms, muscarinic receptors are G-coupled protein receptors, while nicotinic receptors are ligand-gated ion channels. They can be found on both sides of the synaptic cleft (presynaptic and postsynaptic).
After the pressure drops below 40 psi, the electrical switch turns on the pump and the pressure in the tank increases. Any failure in any component or loss of electricity can cause a well to suddenly stop producing water when a faucet is turned on.
The well pump, in turn, could have been damaged or hastened to the end of its life by a bad water pressure tank which has caused well pump short-cycling. Short cycling of the pump motor can burn up the pump relay control. Readers should also see WATER PIPE CLOG DIAGNOSIS. and WATER PIPE CLOG REPAIR.