Final answer:
Neurotransmitters are chemical messengers in the nervous system that can be composed of various substances. Their effects depend on the type of receptor they bind to, and they are eliminated in different ways.
Step-by-step explanation:
Neurotransmitters are chemical messengers that transmit signals between neurons in the nervous system. They can be composed of various substances, not just amino acids. Examples of neurotransmitters include acetylcholine, dopamine, serotonin, and glutamate.
Cholinergic neurotransmitters, such as acetylcholine, can have both excitatory and inhibitory effects, depending on the specific receptor they bind to. For example, acetylcholine can have excitatory effects in skeletal muscles, but inhibitory effects in the heart.
The postsynaptic effects of neurotransmitters depend on the type of receptor present on the receiving neuron. Different neurotransmitters can bind to different types of receptors, which can lead to either excitatory or inhibitory effects.
Neurotransmitters are eliminated in different ways. Some neurotransmitters are broken down by enzymes, while others are reabsorbed back into the presynaptic neuron through a process called reuptake.
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