The first identified neurotransmitter was

When neurons fire and transmit messages, they

A molecule of neurotransmitter is to a(n) _____ as a key is to a keyhole.

Endorphins help the body to

An _____ is a chemical substance that mimics or enhances the effects of a neurotransmitter.

To help control Chloe's nausea, Chloe's doctor gives her Zofran, which blocks the action of serotonin, a chemical involved in the body's nausea response. In Chloe's case, the medication prescribed by her doctor acts as an

_____ is the release of a neural impulse, consisting of a reversal of the electrical charge within the axon.

The first identified neurotransmitter was