Neurotransmitters

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Neurotransmitters are chemical messengers that play a crucial role in the communication between neurons and other cells in the body during synaptic transmission. These chemicals are typically produced in nerve endings and are released from the axon terminals of a neuron into the synaptic cleft, where they bind to receptors on the surface of a neighboring neuron or target cell. Depending on the type of neurotransmitter and receptor involved, this interaction can either excite, inhibit, or alter the function of the target cell.

There are generally considered to be two types of neurotransmitter receptors: ionotropic and metabotropic. Ionotropic receptors are typically ligand-gated ion channels, through which ions pass in response to the binding of a chemical messenger, such as a neurotransmitter. Ionotropic receptors are fast-acting, leading to fast synaptic transmission and mediating fast, transient responses. Metabotropic receptors do not form an ion channel pore, instead they require G proteins and secondary messengers to indirectly modulate ionic activity in neurons. G protein-coupled receptors (GPCRs) represent the largest family of metabotropic receptors. Since opening channels by metabotropic receptors involves activating a number of molecules in the intracellular mechanism, these receptors are slower-acting and have more prolonged effects on cellular function than ionotropic receptors.

Neurotransmitters can be grouped according to their chemical structure. In this system of classification, the primary categories include monoamines, amino acids, neuropeptides and an additional 'others' group for neurotransmitters that don't fit neatly into these three main categories. Neurotransmitters can also be classified according to their function into either excitatory or inhibitory neurotransmitters. Excitatory neurotransmitters function to activate receptors on the postsynaptic membrane and enhance the effects of the action potential. Inhibitory neurotransmitters on the other hand function to prevent an action potential. It should be noted that some neurotransmitters can be classified as either excitatory or inhibitory based on the receptors they bind to.

Overall, there are more than 40 neurotransmitters in the human nervous system and each has a specific function. For example, dopamine is involved in reward and pleasure, serotonin regulates mood and sleep, while acetylcholine plays a role in muscle control. Neurotransmitters are not only crucial for motor control and sensory perception, but also for processes like learning, memory and mood regulation. Disruptions in neurotransmitter systems are linked to various neurological and psychiatric conditions, such as depression, Parkinson's disease and schizophrenia. Understanding how neurotransmitters work is fundamental to the study of neuroscience and is key to developing treatments for these conditions.

The following video will help you learn more about the major classes and most common types of neurotransmitters.

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Neurotransmitter receptor types

Neurotransmitter receptors are typically classified into two main types: ionotropic and metabotropic. Take a look at the mechanism of action for each below.

Excitatory vs. inhibitory neurotransmitter mechanisms

Excitatory and inhibitory neurotransmitters affect the postsynaptic neuron in distinct ways. Discover how each mechanism works below.

Common neurotransmitters

There are over 40 neurotransmitters at work in the human body. Learn more about the most common types below.

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