How do neurotransmitter muscle contractions take place

Neurotransmitters

A neurotransmitter is a messenger substance in the human body. Here we explain what neurotransmitters are, how they work and what types there are.

  • What are neurotransmitters?
    in the text
  • Neurotransmitter mode of action
    in the text
  • Neurotransmitter receptors
    in the text
  • Neurotransmitter classification
    in the text
  • Neurotransmitter Examples
    in the text
  • Neurotransmitter sympathetic
    in the text

What are neurotransmitters?

The word Neurotransmitters is made up of the words neuron (= Nerve cell) and transmittere (= transferred) together.

So you are designating a kind of transmitter. More precisely, a chemical molecule that transmits signals between nerve cells. The signal transmission from one nerve cell to the next takes place at special contact points - the synapses.

This causes the neurons to stand in contact and can communicate with each other. This is how the nerve cells in your body transmit electrical signals (excitation transmission).

Neurotransmitter definition

Neurotransmitters or transmitters for short are chemical molecules that transmit signals at chemical synapses from one nerve cell to the other (synaptic transmission).

Neurotransmitter mode of action

A neurotransmitter transmits a signal from the nerve cell in front of the synapse (presynaptic) to the nerve cell behind the synapse (postsynaptic).

This is accompanied by an incoming electrical signal in a chemical signal converted, which in turn triggers another electrical signal.

It works like this, step by step:

  1. An electrical signal (action potential) reaches the presynaptic nerve cell. There the neurotransmitters are stored in membrane-covered vesicles.
  2. The vesicles fuse with the presynaptic membrane (fusion). As a result, the cell releases the messenger substances into the synaptic gap (= exocytosis).
  3. The neurotransmitters diffuse through the gap to the postsynaptic membrane. There are special docking points (receptors) for the molecules. Only one specific molecule can bind to each receptor.
  4. So for every neurotransmitter there is specific receptors. The molecule binds to this and thus leads to the opening of ion channels.
  5. Ions (charged particles) can now flow in or out through the ion channel. This creates an electrical signal again in the postsynaptic nerve cell. This can either have an activating (EPSP) or an inhibiting (IPSP) effect on the cell.
  6. The neurotransmitters in the synaptic gap are broken down by special enzymes. Then the presynapse can pick up the transmitters again and use them again.

Neurotransmitter receptors

So there are specific ones for each neurotransmitter postsynaptic receptors. They determine whether a neurotransmitter has an activating or inhibiting effect. Consequently, the type of transmitter has no influence on whether you find an excitatory synapse (exciting) or an inhibitory synapse (inhibitory). It only depends on the receptor, so the same molecule can have two opposing effects.

You can differentiate between two different types of receptors according to how they work:

  • ionotropic receptors (= ligand-controlled ion channels): They are both a receptor and an ion channel.
  • metabotropic receptors (= G-protein coupled receptors): They indirectly control the opening of ion channels. The opening is triggered by a downstream signal cascade, i.e. a chain of several steps.

Neurotransmitter classification

You can use the transmitter molecules themselves divide into different classes. To do this, you look at the chemical properties and then arrange them Substance class to. First there is a division into neuropeptides and low molecular weight transmitters. You can then break them down further into amino acids and amines. An overview of the three types of neurotransmitters can be found in this table:

Substance classExamples
amino acidsGlutamic acid (glutamate), glycine, γ-aminobutyric acid (GABA)
AminesAcetylcholine, serotonin, catecholamines (adrenaline, noradrenaline, dopamine)
NeuropeptidesEndorphins, oxytocin

Neurotransmitter Examples

There are many different neuronal messengers that transmit signals in your body. An overview of important neurotransmitters - namely Acetylcholine, Glutamate, GABA, Serotonin and Dopamine - we give you here.

Acetylcholine neurotransmitter

The neurotransmitter Acetylcholine plays an important role in both the peripheral and the central nervous system. In the peripheral nervous system, it mediates the signals between nerve and muscle cells at the so-called motor end plate. In addition, acetylcholines are one of the messenger substances that occur most frequently in the brain (central nervous system, CNS).

In the autonomic nervous system, acetylcholine serves as a transmitter substance in neurons of the sympathetic and parasympathetic nervous systems.

There are two different acetylcholine receptors (cholinergic receptors) that influence the action of acetylcholine: the nicotinic acetylcholine receptor and the muscarinic acetylcholine receptor. Nicotinic receptors are ionotropic receptors, so they form ion channels themselves. The muscarinic receptor, on the other hand, is a metabotropic receptor that indirectly opens ion channels.

Glutamate neurotransmitters and GABA neurotransmitters

The neurotransmitter Glutamate (Salt of glutamic acid) is an amino acid. Glutamate has one in the brain (CNS) exciting Effect and is the most common excitatory transmitter there.

It is also the precursor of the transmitter γ-aminobutyric acid (GABA). The GABA synthesis takes place through the decarboxylation (removal of the carboxyl group) of the glutamic acid.

Again, GABA is the most common inhibiting Messenger substance in the central nervous system. This means that the glutamate effect and the GABA effect are opposite.

The GABA system also works via ionotropic (GABAA.Receptor) and metabotropic (GABAB.Receptor) receptors.

Serotonin neurotransmitter

The neurotransmitter Serotonin is important for signal transmission in the central nervous system. There serotonin has an effect on sleep, pain perception, eating and sexual behavior and emotions. It creates a good mood and serenity.

In depression, therefore, there is often a reduced serotonin concentration. That is why dopamine and serotonin are also called "Happiness hormones" designated.

Dopamine neurotransmitter

The neurotransmitter Dopamine belongs to the so-called catecholamines along with adrenaline and noradrenaline.

Dopamine synthesis takes place primarily in the adrenal medulla and in the hypothalamus in the brain. It is an intermediate in the production of norepinephrine and epinephrine from the amino acid tyrosine.

The dopamine effect is in various control processes, like the Motion control and the reward system, recognizable. The death of dopaminergic neurons in Parkinson's disease therefore leads to a sedentary lifestyle and even immobility. Hence, dopamine drugs are used to treat Parkinson's disease. However, dopamine cannot cross the blood-brain barrier. Therefore precursors to dopamine must be used.

Neurotransmitter sympathetic

Dopamine can also increase the effectiveness of the sympathetic system. The Sympathetic is part of the autonomic nervous system that controls the activity of many organs. Its neurons are regulated by the neurotransmitters acetylcholine and norepinephrine. So you see what an important role the neurotransmitters play throughout the body.