What Are Neurotransmitters?
The human body has to communicate with itself. The brain must send messages to all of the other parts of the body to give them instructions on how to function, and the various cells in the body need to send messages to the brain. All of this is required in order to keep the body in a state of homeostasis, a state of equilibrium where the body is functioning as well as it possibly can. The body uses chemicals to communicate. The chemical messengers are known as neurotransmitters. Neurotransmitters and the nerves they work with are a crucial part of how humans’ function.
How Do Neurotransmitters Work?
In order for messages to travel around the body, they must travel between neurons. The neurons are the nerve cells that transmit and receive information between other cells such as other nerve cells, gland cells, tissue cells, muscle cells etc. A neuron is a very specialized cell designed to send messages. Neurotransmitters are the chemical messengers that carry information between neurons. While messages are transmitted around the body in the form of electrical charges, an electrical charge cannot cross a synapse (a synapse is the tiny space between cells). This means that in order for messages to travel from one cell to another, the electrical charge is converted into a chemical messenger that can cross a synapse and then be converted into an electrical charge again.
Neurotransmitters are stored within storage areas in neurons. These storage compartments are called synaptic vesicles. The neurotransmitter chemicals stored within the synaptic vesicles wait for a triggering message from the brain. When the brain sends out that message, in the form of an electrical charge, the neuron gives an order which is called an action potential. The action potential stimulates the neurons, and this releases the neurotransmitters and they cross the space (known as the synapse) between the neuron and the next neuron along. This has a knock-on effect on other neurons. Once the given order has been given and completed and the neurotransmitters are no longer required for the action, they are absorbed by the synaptic vesicles or are broken down and dissipated.
What are Neurons?
Neurons are the nerve cells of the brain. They are so numerous that scientists can never be sure how many there are. There are literally billions of these essential cells within your brain.
A Recent Science
The action and function of neurotransmitters is a relatively recent scientific understanding. Long before we knew anything about chemical messengers, it was understood that the brain communicated using electrical signals. It wasn’t until a scientist by the name of Ramon y Cajal discovered the synaptic gap between neurons. This raised questions over how messages were passed on between neurons, as the theory of electrical charges didn’t go far enough to explain how this gap was crossed. The solution was that the electrical charge must trigger a chemical action. This was only confirmed by a pharmacologist called Otto Loewi in the 1920s. Loewi went on to identify the first neurotransmitter (acetylcholine) and since then many new ones have been discovered and so the study of neurotransmitters is a relatively young science.
What Are Neurotransmitters Made Of?
Are There Different Types of Neurotransmitters?
Scientists have identified around a hundred different neurotransmitters with various functions within the human body but there may be many more. Some of these chemical messengers are more important than others, and they each fall into one of two categories. Firstly, there are excitatory neurotransmitters; these are designed to trigger the cells of the brain to send out messages. Then there are second types, and these are inhibitory neurotransmitters. The purpose of these ones is to stop messages being sent. You can think of these different groups like on switches and off switches, each either triggering a flow of information to begin or triggering it to stop.
None of us could function without neurotransmitters. We need them to control almost everything we do. They trigger our bodies to tell us what we need so that our needs can be met. They help us stay aware of danger and avoid risk. They enable us to sleep, to eat and for all of the bodily functions that we aren’t even aware of to happen naturally.
Why is Studying Them Important?
Being able to understand the action of neurotransmitters in the brain can help the medical world identify problems and source solutions for them. For example, an imbalance of neurotransmitters can result in some very debilitating conditions and symptoms. Cognitive function can suffer, depression, anxiety, appetite issues and sleep problems can occur, and energy levels can be severely affected. There is also a connection between neurotransmitters and addiction. Hormonal problems can also result.
For those suffering from depression, mood disorders or anxiety, doctors often prescribe a type of antidepressant known as an SSRI (selective serotonin reuptake inhibitor). This medication increases the level of serotonin that is available for the brain to use as an essential neurotransmitter. These medications are effective for many people in treating mood problems.
Seven Major Neurotransmitters
Let’s take a look at some of the major neurotransmitters and what they do. These ‘small molecule’ neurotransmitters are responsible for a very wide range of different functions. They are each unique and work in different ways to have different effects.
What is it?
Dopamine is one of the neurotransmitters you are most likely to have heard of. That is because it is often cited as an important brain chemical because of its role in the reward system of the brain.
What does it do?
When you do something rewarding, such as succeeding at a challenge, winning something, making a connection with a person or even to a lesser extent a simple thing like just eating a satisfying meal, that sense of wellbeing – or reward – is thanks to dopamine. Dopamine enters the synapse between the neurons and gives you that sense of accomplishment. It is a good feeling, and so dopamine has a reputation for being one of the brain’s happy chemicals. So next time you go for a run and beat your personal best (or simply manage to reach the end of it!) and you feel a sense of pride and a buzz of happiness, that is dopamine. If you meet your target at work, while you may be motivated by the thought of reward for your hard work, you will also have a sense of personal success that makes the task feel like it was worth it. That’s dopamine too!
Dopamine plays a role in many functions of the body besides the reward system of the brain. It also helps us to be alert, aids with proper metabolism and insulin release and plays a part in healthy and effective motor skills so we can move with precision and efficiency.
However, there is a darker side to this reward system. Dopamine plays a role in addictive behavior; some people are genetically predisposed to experiencing larger highs of dopamine when they do certain things. It may be using a substance such as alcohol, tobacco, or drugs. It may be gambling, shopping, gaming, or some other compulsive behavior. The rush that a person gets from doing these things comes down to a flood of dopamine, and it can be more than difficult to resist; it can be nearly impossible. Some substances, often found in recreational drugs, overstimulate the production of dopamine. This gives a great ‘high’, or sense of reward and wellbeing for a short time but then results in feelings of depression, anxiety, fatigue, and apathy after the levels of dopamine crash. This is a further reason for people becoming addicted to these types of substances.
What is it?
Acetylcholine is a neurotransmitter associated with the muscle system. This is where the muscles and the nervous system interact, and acetylcholine plays a huge role in making this happen so that we can move.
What does it do?
Without acetylcholine, none of us would be able to move. It is quite different from other neurotransmitters as it is released and absorbed by receptors within the muscle tissue. This tells the muscles to do whatever it is the brain has decided they need to do. This all happens so quickly we aren’t even aware of it. Remember that the muscles in the body are not just those we think of in the arms and legs; the heart is also a muscle and cannot beat without contracting.
Think about when someone throws a ball to you, and you catch it as a reflex action without ever making a conscious choice to do so. That is how fast and effective acetylcholine is at communicating and making the muscles work. This amazing substance is at work in the body all the time, keeping the heart pumping, moving food through the digestive process, ensuring you can talk, eat, blink, and move. Almost every function of the body requires the neurotransmitter acetylcholine to work.
What is it?
We consume glutamate in many foods, and it acts as a neurotransmitter that triggers our neurons. In fact, it is the most important excitatory neurotransmitter and is found in almost all the synapses in the body.
What does it do?
Glutamate is a neurotransmitter that gets the brain cells fired up when it is released. It quickly bridges the synaptic space and sends information whizzing along the nervous system. Many of the brain functions rely on glutamate; it is essential for cognitive function, learning and memory.
When it is finished doing its job, it is swept up by other substances that block it. This is because the brain is so sensitive to glutamate that if it became overwhelmed with it, it becomes over-stimulated. So, while glutamate is essential, so are the glutamate transporters that absorb and move the glutamate when it has finished doing its job. It is important to have neurotransmitters doing their jobs, but it is also important not to let the body become overwhelmed by them.
GABA (y-aminobutyric acid)
What is it?
GABA is the most important of the inhibitory type of neurotransmitters. It essentially stops signals being sent and blocks messages. This might not sound like a very important thing, but it is absolutely essential to our health and wellbeing.
What does it do?
GABA is the great calmer. It brings the heart rate down, slows us down and enables us to ‘switch off’. Can you imagine what life would be like if you were on high alert all the time? If you were in a constant state of stress, excitement, or nervous arousal? If we didn’t have the calming influence of GABA, this is what life would be like, and it would doubtless be impossible for us to function effectively for long. We need to switch off, to come ‘down’ and to rest.
The circadian rhythms are associated with GABA. So, we produce more of it when it is time to rest, when things become quieter and darker. This is partly why we often find it difficult to ‘switch off’ if we have been doing something strenuous, experiencing excitement or anxiety or if we have been exposed to light.
What is it?
Serotonin has a number of functions, and it depends on where the serotonin is. When serotonin acts in the brain, it affects your mood and sleep patterns. When serotonin acts in the gut, it helps with appetite, fullness, and appetite. This makes it a fundamental neurotransmitter for many of the body’s most important systems.
What does it do?
In the brain, serotonin plays a huge role in the natural circadian rhythms that affect when we are awake and when we are asleep. This is a little like a body clock that tells us to sleep when it’s dark and be alert when it’s light. The serotonin in our brains also impacts on our mood. Serotonin releases help us feel happy and content. They boost our sense of wellbeing and help us to be motivated and positive. Low levels of serotonin are associated with depression and anxiety and the associated dullness of mental acuity and sleep disturbances.
Serotonin gets to work in the gut, balancing your appetite and giving you a sense of satisfaction after a meal. It also ensures that we get rid of foods that disagree with us (through prevention by making us feel nauseated when we come into contact with spoiled food, or through elimination by vomiting or diarrhea). Many people know that serotonin plays a role in the brain, but fewer people realize that serotonin helps you to avoid rotten food and creates an aversion to eating things that might cause the body harm. Think about if you see a truly disgusting food or smell something truly foul. The urge to gag or vomit can be very strong. This is to prevent us from eating dangerous things, even if we are very hungry. This is a survival method, and it’s all thanks to serotonin.
Again, some recreational drugs affect serotonin levels and create a huge ‘high’ that later crashes to leave potentially dangerous low levels that can cause memory loss, dramatically affect your ability to make good decisions and judge situations rationally, and also create feelings of paranoia and extreme anxiety.
What is it?
One of the most well-known of the neurotransmitters – and indeed of all the chemicals in the human body – is epinephrine, which is more commonly known as adrenaline. Even if you aren’t quite sure what it does, you will probably have heard of an adrenaline rush – the high that people feel when something exciting is happening.
What does it do?
Perhaps you have heard of people doing incredible things because they were high on adrenaline and so they were stronger or faster than usual. When something happens to stimulate adrenaline production, the body’s ‘fight or flight’ system kicks into action. The stimulation might be caused by a genuine emergency, or it may be a perceived threat. It might be something bad like a big dog jumping out and giving you a fright, or it might be something good like the prospect of a holiday. That ‘butterflies in the tummy’ feeling that we get when anxious or excited can be attributed to our friend adrenaline.
Adrenaline rushes through the body very quickly because it has to so we can react quickly. It speeds up the heart rate and delivers blood flow to where you need it – your limbs – so you can run away or fight if you have to. It also makes you mentally sharper, so you are alert to any threats and ready for action. It can feel very thrilling or very stressful. Remember a lot of the threats that faced us throughout the evolution of human life were very real physical things that require physical responses. This is why a looming deadline, an argument with a friend or not being able to find your car keys can cause actual physical sensations that are really our bodies ramping up to face something scary. We don’t often have to fight wild animals or run for our lives these days, so all that excess energy and blood flow can cause a lot of anxiety.
What is it?
Oxytocin is known as the love hormone because it is closely associated with feelings of love between romantic partners and bonding between parents and children. It is an incredibly important neurotransmitter and scientists are discovering more about it as they research this fascinating substance. It also has lots of other functions, most notable in giving birth and breastfeeding.
What does it do?
Oxytocin is all about bonding. It connects a mother to her baby with powerful feelings of love and protection (and also plays a role in some of the anxieties and fears that come with having a child too!). It is released during breastfeeding and when holding a baby close, to help parent and child bond so that the connection is strong, and the baby is cared for. This same chemical is what triggers the woman to go into labor in the first place; it is oxytocin we have to thank for those powerful contractions in the walls of the uterus that occur when it is time to deliver the baby.
However, the role of oxytocin extends far beyond the mother and child bond and the birthing process. It is also crucial for men. In the male body, oxytocin plays a role in the protective feeling that a man feels about his family and helps forge connections and boost loyalty and trust. This is important for creating social bonds and forming family units that make up societies.
Neurotransmitters are incredibly complex chemicals, and yet they are some of the most fundamental building blocks of our nervous system. We owe everything our bodies can do to the action of these chemicals. No part of the body operates without neurotransmitters, and they are at their most powerful within the brain; the command center of the body that must communicate with the rest of the body in order for us to function. Incredible!
It is known to many that the functioning of the human brain is based on the transmission of bioelectric signals. This transmission implies the presence of a series of elements that transmit information from one neuron to another, these elements being...
Everything that happens within the human body is linked to chemical reactions. Everything we feel, what we do, the functions of our organs, and many other things. The regulation of all our physiology is from neurotransmitters and hormones. There is a crucial molecule...
The nervous system is a complex set of cells in charge of controlling, supervising, and directing all the activities and functions of our organs and organism in general. It captures stimuli from the environment (external stimuli) or signals from the same organism...
Neurotransmitters are substances that are synthesized within the body and that act as chemical messengers and transmit the signal from a neuron to the target cell through the synapse. There are two general types of these substances; the Excitatory and Inhibitory...