Answer:
Receptor
Explanation:
Neurotransmitters are defined as chemical messengers that carry, stimulate and balance signals between neurons, or nerve cells and other cells in the body.
After release, the neurotransmitter crosses the synaptic gap and binds to the receptor site on the other neuron, stimulating or inhibiting the receptor neuron depending on what the neurotransmitter is. Neurotransmitters act as a key and the receptor site acts as a block. It takes the right key to open specific locks. If the neurotransmitter is able to function at the receptor site, it will cause changes in the recipient cell.
The "first-class" neurotransmitter receptors are ligand-activated ion channels, also known as ionotropic receptors. They undergo a change in shape when the neurotransmitter turns on, causing the channel to open. This can be an excitatory or inhibitory effect, depending on the ions that can pass through the channels and their concentrations inside and outside the cell. Ligand-activated ion channels are large protein complexes. They have certain regions that are binding sites for neurotransmitters, as well as membrane segments to make up the channel.
