The use of the word rank for Navy enlisted personnel is incorrect. The term is rate.. The rating badge is a combination of rate (pay grade, as indicated by the chevrons) and rating (occupational specialty, as indicated by the symbol just above the chevrons).
Neurons are nerve cells that are constantly sending signals to your brain, muscles and glands. You have over 100 billion neurons in your brain sending signals. The signals help the different parts of your body communicate with each other.
To make a muscle contract, the acetylcholine produced in the presynaptic neuron of the neuromuscular junction must bind to the nicotinic receptors on the postsynaptic side. Each of these receptors consists of 5 subunits that form a pentagonal structure around a central channel.