In this way, the original impulse is conducted through the sending neuron-and through the rest of the neurons in a nerve pathway. Eventually, the impulse reaches its final destination, such as a muscle, gland, or organ. The result is a change in the way we think, feel, or behave. Binding passes on the message. The chemical reactions inside the receiving neuron are called second messengers.
Second messengers pass along the original message from the neurotransmitter.
In fact, neurotransmitters are sometimes called first messengers.