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.
Over-hydration and water intoxication happens when you drink more water than your kidneys can get rid of via urine. But the amount of water isn't the only factor. How long you take to drink the water also counts. You have a greater risk of developing water intoxication if you drink a lot of water in a short period of time. The risk is less if you drink the same amount over a much longer period of time. Symptoms of hyponatremia can occur from as little as 0.8-1 gallons (3-4 liters) of water in a short amount of time .