Neurotransmitters

A neurotransmitter is a chemical transmitter or messenger that passes signals across a chemical synapse, between two neurons, or from one neuron to a gland or cell of muscle.

Neurotransmitter Definition

The neurotransmitter is known as the chemical transmitter of a body. Neurons release various chemical agents that can stimulate another neuron, muscle, or gland cell. These chemical compounds transmit impulses through cells of the nervous system.

This signal transmission occurs in the neuron junction or synaptic. The passing electrical signals of neurons are transferred into chemical signals while transmitting through neurotransmitters.

Types of Neurotransmitters

In the nervous system, various types of neurotransmitters are present. They are-

  • Excitatory Neurotransmitters

By activating receptors, this type of neurotransmitter increases the effects of an action potential. Norepinephrine and Epinephrine are two examples of excitatory neurotransmitters.

  • Inhibitory Neurotransmitters

These neurotransmitters decrease or prevent an action potential of the target cell. Moreover, a relaxation-like effect can be triggered through these neurotransmitters. 

Example: Gamma amino-butyric acid or GABA, Serotonin.

  • Modulatory Neurotransmitters

They can transmit messages to several cells simultaneously and also help to communicate with chemical transmitters. 

These are the main types of neurotransmitters and their functions. However, other than the above-mentioned categories, there are other types of neurotransmitters found in cells. Here is a list of neurotransmitters-

  • Amino acids: GABA, Glutamate.

  • Peptides: Endorphins, Oxytocin.

  • Monoamines: Dopamine, Epinephrine, Serotonin, Histamine, Norepinephrine.

  • Purines: Adenosine triphosphate, Adenosine.

  • Gasotransmitters: Carbon monoxide, Nitric oxide.

  • Acetylcholine: Acetylcholine.

Exercise:

1. Define Neurotransmitter.

Ans. Neurotransmitters are chemical transmitters that send impulses from one neuron to another neuron, muscle, or gland cell across a chemical synapse. 

2. Which of the Following is a Neurotransmitter?

a) Adrenaline b) Cortisol c) Acetylcholine d) Insulin

Ans. Acetylcholine is a neurotransmitter. 

Neurotransmitter Diagram

Identification of a Neurotransmitter

The body creates different chemical molecules to run various functions. However, not all of them are neurotransmitters. Thus, to identify a neurotransmitter, here are some guidelines-

  • The chemical compounds called neurotransmitters are only created inside neuron cells.

  • Precursors of enzymes are usually present in the neurons.

  • Neurons always contain a chemical compound to stop a neurotransmitter's action.

  • Presynaptic neurons release these chemicals, and the receptor cells presented on postsynaptic neurons receive and bind it.

Ways to Stop the Activities of Neurotransmitters

Neurotransmitter’s activity can be restricted with the help of these following ways-

  • Chemicals which are produced to restrict the activities of neurotransmitters are called precursor enzymes. These enzymes can deactivate neurotransmitters.

  • A neuron can take back the chemical transmitters even after releasing it.

  • By moving away from the receptor cells, it can be deactivated.

Neurotransmitter Diseases

The following neurotransmitter diseases affect the functions of these chemicals, such as their transportation, synthesising, and breaking down.

Some Common Diseases are-

  • Alzheimer’s Disease

This is a neurodegenerative disorder that can be characterised by memory and learning impairments. Lack of acetylcholine is the reason for this disease.

  • Parkinson’s Disease

Because of the dopamine depletion, the nervous system loses control over muscles. Uncontrollable muscle tremors are known as Parkinson’s disease.

  • Depression

Depletion of neurotransmitters – dopamine, norepinephrine, and serotonin is the reason for depression. The patients are treated by increasing these chemicals in their nervous system. 

  •  Schizophrenia

The presence of excessive dopamine inside the frontal lobes causes schizophrenia. Patients of this severe mental disease experience psychotic episodes and they are treated by using drugs that can block dopamine.

  • Epilepsy

Patients suffer from epilepsy either because of the lacking of inhibitory neurotransmitters like GABA, or due to the presence of excessive excitatory neurotransmitters like glutamate. Patients suffering from epilepsy are treated by judging the exact reason among these.

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FAQ (Frequently Asked Questions)

1. What is the List of Neurotransmitters and What are Their Functions?

Ans. The list of neurotransmitters consists – excitatory, inhibitory, and modulatory neurotransmitters. Excitatory neurotransmitters increase the potential action of a target cell. Inhibitory neurotransmitters decrease the potential action of a receptor cell by encouraging relaxation of a cell. Modulatory neurotransmitters help the neurons to communicate with each other by sending signals.

2. What are the Examples of Neurotransmitters?

Ans. Seven major examples of neurotransmitters are – Dopamine, Histamine, Acetylcholine, Glutamate, GABA, Serotonin, and Norepinephrine.

3. What is the Role of a Neurotransmitter?

Ans. Neurotransmitters are the chemical molecules used by neurons to transmit signals throughout the nervous system. Thus, neurotransmitters play the role of a chemical messenger of the body.