Question

what are neurotransmitters?
hormones that regulate the bodys metabolism.
proteins that transport oxygen in the blood
ions that regulate the ph in the body
chemical messengers that bind to receptors on the next neuron, transmitting the signal across the synapse.
antibodies that fight off infections

Explanation:

Neurotransmitters are chemicals released by neurons at synapses. They bind to receptors on the next - neuron to transmit signals. Hormones regulate metabolism, proteins like hemoglobin transport oxygen, ions regulate pH, and antibodies fight infections.

Answer:

Chemical messengers that bind to receptors on the next neuron, transmitting the signal across the synapse.