Images and Descriptions of Neurotransmitters


An Image of Acetylcholine Acetylcholine was the first neurotransmitter be be identified.. Image courtesy Wikimedia Commons

A neurotransmitter is a chemical messenger that carries, boosts and modulates signals between neurons and other cells in the body.

When signals cross from one neuron to another, neurotransmitters are used to get the message across the synapse connecting the two cells. A synapse is the junction point between two neurons. The terminal button of a neuron contains vesicles filled with neurotransmitters. The chemical messengers are secreted into the synaptic gap, which they then cross and are reabsorbed by the receptors on the post-synaptic neuron.

However, neurotransmitters can also carry messages from neurons to other types of cells. Sensory cells transmit information to neurons and neurons send information to muscles, organs and glands in the body.

While over 100 different neurotransmitters have been identified, researchers are still unsure of exactly how many different chemical messengers exist. Neurotransmitters are categorized as one of six different types: acetylcholine, amino acids, neuropeptides, monoamines, purines and lipids/gases.

In this gallery, we will look at three of the body's major neurotransmitters: acetylcholine, serotonin and dopamine. Some of the other major neurotransmitters in the body include GABA (gamma-aminobutyric acid), glutamate and norepinephrine.

Check out images of some of the major neurotransmitters in this gallery.

You can also learn more about some of the different ways that neurotransmitters act in the body in the following resources:


Thompson, R.F. (2000). The Brain: A Neuroscience Primer. New York: Worth Publishers.

Acetylcholine (often abbreviated ACh) was not only the very first neurotransmitter to be discovered, it is the most common neurotransmitter. This chemical messenger is located in both the central nervous system and the peripheral nervous system.

Remember, neurotransmitters are chemical messengers that not only carry signals from neurons to other cells in the body, they can also be used to boost and modulate these signals. Acetylcholine performs several functions including carrying signals to muscle groups, acting on neurons in the sympathetic and parasympathetic systems and acting in areas of the brain associated with motivation, attention and arousal.

Learn more about acetylcholine.


An Image of Serotonin In the central nervous system, serotonin helps regulate mood, sleep, appetite, learning and memory.. Image courtesy Wikimedia Commons

Serotonin is a type of neurotransmitter that is found mainly in the central nervous system and the gastrointestinal (GI) tract.

In the central nervous system, serotonin is associated with the regulation of memory, sleep, learning, appetite and mood. While the majority of the body's serotonin is found in the digestive tract, most neurons in the brain are either directly or indirectly influenced by this neurotransmitter.

Learn more about serotonin.


An Image of Dopamine In the brain, dopamine plays an important role in functions including sleep, motivation, attention and mood.. Image courtesy Wikimedia Commons

Dopamine is both a neurotransmitter and a neurohormone that is produced in several different areas of the brain.

Dopamine is thought to play a role in a variety of brain functions including voluntary movement, sleep, memory, attention, cognition and motivation. Certain disorders including Parkinson's disease are associated with disruptions in dopamine production.

Learn more about dopamine.

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