Transmitter

An overview of neurotransmitters in the human body

Introduction

A neurotransmitter is a chemical substance that transmits signals across a synapse from one neuron to another 'target' neuron, muscle cell, or gland cell. Neurotransmitters are essential for the proper functioning of the nervous system, facilitating communication between neurons and other cells.

Types of Neurotransmitters

Neurotransmitters can be broadly classified into several categories based on their chemical structure and function:

Amino Acids

Amino acid neurotransmitters are the most prevalent in the central nervous system. They include:

• Glutamate: The primary excitatory neurotransmitter in the brain, involved in cognitive functions such as learning and memory.
• GABA: The main inhibitory neurotransmitter, which helps to reduce neuronal excitability throughout the nervous system.

Monoamines

Monoamines are neurotransmitters derived from aromatic amino acids. They include:

• Dopamine: Involved in reward, motivation, and motor control.
• Serotonin: Plays a role in mood regulation, appetite, and sleep.
• Norepinephrine: Important for attention, emotions, sleeping, dreaming, and learning.

Peptides

Peptide neurotransmitters are composed of short chains of amino acids. Examples include:

• Substance P: Involved in the transmission of pain information.
• Endorphins: Act as natural painkillers and are involved in the "feel-good" response.

Others

Other neurotransmitters include:

• Acetylcholine: Involved in muscle activation and memory.
• Nitric oxide: A gaseous neurotransmitter involved in vasodilation and neurotransmission.

Mechanism of Action

Neurotransmitters are released from the synaptic vesicles in the presynaptic neuron into the synaptic cleft. They then bind to specific receptors on the postsynaptic cell, leading to either excitation or inhibition of the postsynaptic neuron. This process is crucial for the propagation of nerve impulses.

File:Synapse Diagram.svg

Diagram of a synapse showing neurotransmitter release.

Role in Disease

Imbalances in neurotransmitter levels are associated with various neurological and psychiatric disorders. For example:

• Parkinson's disease: Characterized by low levels of dopamine.
• Depression: Often linked to imbalances in serotonin and norepinephrine.
• Schizophrenia: Associated with dysregulation of dopamine pathways.

Conclusion

Neurotransmitters are vital for the communication between neurons and play a critical role in maintaining the body's homeostasis. Understanding their function and regulation is essential for developing treatments for various neurological disorders.

Related pages

• Nervous system
• Synapse
• Neuron
• Receptor (biochemistry)