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.
Water retention occurs when fluid builds up in the body. In most cases, fluid retention does not cause serious problems. But sometimes, fluid retention causes dangerous effects on the body. Conditions that cause fluid retention include heart failure, cirrhosis of the liver, kidney failure, premenstrual syndrome and preeclampsia. Discuss water retention with a physician if you are concerned about the dangers of this symptom.