Neurotransmitters are chemical molecules released by the neurons to bridge the gap between and to be able to communicate. This is a process in which one side of the communication is the source of the neurotransmitters and the other is the receptor which is often used as a lock-key example. Since the neurotransmitter is the component which bridges the gap and in a sense unlocks the door, it is the key. The receptor is the part affected by the neurotransmitter which means that is the lock part of this example.
No it’s not alive it just has adhesion as a property. It doesn’t have cells that make it living, and it doesn’t make or eat food to survive. And the force from the waves make it roll up on the beach, not because it’s alive.
