Neurotransmitters are chemical messengers in the body. They transmit signals from nerve cells to target cells. These target cells may be in muscles, glands or other nerves. These messages help you move your limbs, feel sensations, keep your heart beating and respond to all information your body receives from other internal parts of your body and your environment. Here are the short list of functions that your nervous system controls using neurotransmitters

  • Heartbeat and blood pressure
  • Breathing
  • Muscle movement
  • Memory, learning and feeling
  • Sleep, healing and aging
  • Stress management
  • Digestion and sense of hunger and thirst

Before we go into details, please check out this fascinating picture below, we will explore each part further in the next sections. neurotransmitters

How do neurotransmitters work?

Now, lets describe the picture mention above more in detail. You have billions of nerve cells in your body. Nerve cells are generally made up of three parts:

  • A Cell Body: The cell body is vital to producing neurotransmitters and maintaining the function of nerve cell.
  • An Axon: The axon carries the electrical signals along the nerve cell to the axon terminal.
  • An Axon Terminal: This is where the electrical message is changed to a chemical signal (Really wonder how??) using neurotransmetters to communicate with the next group of nerve cells, muscle cells or organs.

Neurotransmitters are located in axon terminal, and are stored within thin-walled sacs called synaptic vesicles. Each vesicle can contain thousands of neurotransmitters. As the signal travels along a nerve cell, the electrical charge of the signal causes the vesicles to fuse with the nerve cell membrane at the very edge of the cell. The neurotransmitters are then released from the axon terminal into a fluid-filled space that’s between one nerve cell and the next target cell. In this space, which is called synaptic junction, each type of neurotransmitter lands on and binds to a specific receptor on the target cell. After they bind, in other words, deliver their message, the molecules must be cleared from the synaptic cleft/junction. They do this in one of the three ways.

  • Fade away, called as diffusion (b in the first picture)
  • Are reabsorbed and reused by the nerve cell that released it. This is called a reuptake process (a in the first picture)
  • Are broken down by enzymes wihtin the synapse so it can not be recognized or bind to receptor cell again. This process is called degradation (c in the first picture)

Even though the first pictures gives a lot of details, please check out the picture below which gives another perspective, as well. neurotransmitters

Classification of Neurotransmitters

Neurotransmitters can be classified under three categories based on the actions in their messages.

  • Excitatory: These neurotransmitters “excite” the neuron and cause it to “fire off the message”, meaning, message continues to passed along to the next cell. In addition, excitatory neurotransmitters encourage a target cell to take an action. Examples of these neurotransmitters are glutamate, epinephrine (a.k.a adrenaline), norepinephrine.
  • Inhibitory: Inhibitory neurotransmitters block or prevent the chemical message from being bassed along any farther. They decrease the likelihood that the neuron will fire and action potential. Some of the inhibitory transmitters are gamma-aminobutyric acid (GABA), seretonin and glycine.
  • Modulatory: Modulatory neurotransmitters, also referred as neuromodulators, influence the effects of other chemical messengers. Neuromodulators are capable of affecting a large number of neurons at the same time.They “tweak” or adjust how cells communicate at the synapse.

NOTE: Some neurotransmitters, such as acetylcholine and dopamine, can create both excitatory and inhibitory effects depending upon the type of receptors that are present.

Types of Neurotransmitters

It is know that, there are at least 100 neurotransmitters and maybe more than that waiting to be discovered. They can be grouped into types based on their chemical nature. Some of the best known categories and neurotransmitter examples and their functions include the following:

Amino acids neurotransmitters

These neurotransmitters are involved in most functions of your nervous system.

  • Glutamate: This is most common excitatory neurotransmitter. It is most generous neurotransmitter in your brain. It plays a key role in congitive functions like thinking, learning and memory. Imbalances in glutamate levels associated with Alzheimer’s disease, dementia, Parkinson’s disease.

  • Gamma-aminobutryic acid (GABA): GABA is the most common inhibitory transmitter. It regulates brain activity to prevent problems in the areas of anxiety, concentration, sleep, seizures and depression.

  • Glycine: Glycine is most common inhibitory neurotransmitter in your spinal cord. It is mainly involved in controlling hearing processing and pain transmission.

Monoamines neurotransmitters

Monoamines regulates consciousness, cognition, attention, and emotion. Many disorders of your nervous system involve abnormalities of monomine neurotransmitters, and many drugs that people commonly take affect these neurotransmitters.

  • Serotonin: Serotonin is an inhibitory neurotransmitter. Serotonin plays an important role in regulating and modulating mood, sleep, anxiety, sexuality and appetite. Selective serotonin reuptake inhibitors (SSRIs) are a type of antidepressant medication commonly used to help depression, anxiety, panic disorder. SSRIs work to balance serotonin levels by blocking the reuptae of serotonin in the brain, which can help improve mood and reduce anxiety.

  • Histamine: Histamine regulates body functions including wakefulness, feeding behaviour, and plays a key role in asthma, bronchospasm. It also plays a role in allergic rections and is produced as part of the immune system’s response to pathogens.

  • Dopamine: Commonly known as the feel-good neurotransmitter. Dopamine is involved in reward, motivation, and addictions. Several highly addictive drugs act directly on the dopamine system. In other words, they increase dopamine levels in the brain. This chemical messenger also plays an important role in the coordination of body movements. Parkinson’s disease which is a degenerative disease that results in motor movement impairments, is caused by the loss of dopamine-generating neurons in the brain.

  • Epinephrine: Epinephrine (also called adrenaline) and norepinephrine are responsible for your body’s so-called “fight-or-flight response” to fear and stress. Epinehprine is considered both a hormone and a neurotransmitter. It stimulate your body’s response by increasing your heart rate, breathing, blood pressure.

  • Norepinephrine: Also called noradrenaline, increases blood pressure and heart rate. Its role is to help mobilize the body and brain to take action in times of danger and stress. Typically, its level is lowest during sleep and highest during stress.

Peptide neurotransmitters

Peptides are polymers or chains of amino acids.

  • Oxytocin: This powerful hormone acts as a neurotransmitter in the brain. It is produced by the hypothalamus and plays a role in social recognition, bonding and sexual reproduction. Synthetic oxytocin such as Pitocin is often used as an aid in labor and delivery. Both oxytocin and Pitocin cause the uterus to contract during labor.

  • Endorphins: Endorphins are your body’s natural pain reliever. They play a role in our perception of pain. Release of endorphins reduces pain. Endorphins can also be triggered by other activities such as aerobic exercise.

Why would a neurotransmitter not work as it should?

Several things can go wrong and affect the regular work of neurotransmitter. Here are some of these problems:

  • Too much or not enough of one or more neurotransmitter are produced.
  • The receptor on the receiver cell is not working properly
  • The cell receptors are not taking up enough neurotransmitters due to inflammation and damage of the synaptic cleft.
  • Neurotransmitters are reabsorbed too quickly.

Conclusion

Neurotransmitters are super important since they manage almost all of our mood during our life. Knowing their properties and details would make us more aware of our lives and feelings. There are a lot of prescribed medicine to solve the problems caused by neurotransmitters, and understanding their affect would make us be more responsible taking them.

Resources

  • https://www.medicalnewstoday.com/articles/326649#endorphins
  • https://qbi.uq.edu.au/brain/brain-functions/what-are-neurotransmitters
  • https://www.verywellmind.com/what-is-a-neurotransmitter-2795394
  • https://my.clevelandclinic.org/health/articles/22513-neurotransmitters