Final answer:
A neurotransmitter is the chemical used to communicate between nerve cells, functioning as a messenger that transmits signals across synapses to stimulate or inhibit other neurons or muscle cells. Option B is correct.
Step-by-step explanation:
The chemical used to communicate between nerve cells is a neurotransmitter. Neurotransmitters are endogenous chemicals that facilitate neurotransmission. They serve as chemical messengers, transmitting signals across a chemical synapse from one neuron to another neuron, muscle cell, or gland cell.
When a nerve impulse arrives at the axon terminal of a presynaptic neuron, neurotransmitters are released into the synaptic cleft. These molecules then travel across the cleft and bind to specific receptors on the postsynaptic cell, leading to either excitation or inhibition of the postsynaptic neuron.
For example, acetylcholine is a neurotransmitter that's released at neuromuscular junctions and is essential for muscle activation. It is also involved in signaling within the autonomic nervous system. Substances that interfere with the action of acetylcholine are known as anticholinergics.