Final answer:
An agonist mimics a neurotransmitter to enhance its effect, while an antagonist blocks or impedes a neurotransmitter's action. Both types of chemicals are vital in cell-to-cell communication and pharmacology.
Step-by-step explanation:
You should be able to differentiate between an agonistic and antagonistic chemical message. An agonist is a chemical that mimics a neurotransmitter at the receptor site, enhancing or facilitating the effects of the neurotransmitter. For example, in the treatment of Parkinson's disease, dopamine agonists are used to mimic the effect of dopamine due to the low levels of this neurotransmitter that are characteristic of the disease.
An antagonist, however, blocks or impedes the normal activity of a neurotransmitter at the receptor, potentially leading to a decrease in the action of the neurotransmitter.
Chemical signals, including agonists and antagonists, are important for cell-to-cell communication, which can occur directly or at a distance via chemical signaling. These signals play critical roles in various physiological processes and can also be the basis of pharmacological treatments.