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Neurons expressing certain types of neurotransmitters sometimes form distinct systems, where activation of the system affects large volumes of the brain, called volume transmission. Major neurotransmitter systems include the noradrenaline (norepinephrine) system, the dopamine system, the serotonin system, and the cholinergic system, among others.
A neurotransmitter receptor is a class of receptors that specifically binds with neurotransmitters as opposed to other molecules. In postsynaptic cells, neurotransmitter receptors receive signals that trigger an electrical signal, by regulating the activity of ion channels. The influx of ions through ion channels opened due to the binding of ...
A neurotransmitter is a type of molecule that carries signals between neurons (nerve cells) at synapses in the nervous system The main article for this category is Neurotransmitters . Wikimedia Commons has media related to Neurotransmitters .
Neuromodulation is the physiological process by which a given neuron uses one or more chemicals to regulate diverse populations of neurons. Neuromodulators typically bind to metabotropic, G-protein coupled receptors (GPCRs) to initiate a second messenger signaling cascade that induces a broad, long-lasting signal.
The structures of receptors are very diverse and include the following major categories, among others: Type 1: Ligand-gated ion channels (ionotropic receptors) – These receptors are typically the targets of fast neurotransmitters such as acetylcholine (nicotinic) and GABA ; activation of these receptors results in changes in ion movement ...
Moreover, some molecules may fit into more than one class, e.g. epinephrine is a neurotransmitter when secreted by the central nervous system and a hormone when secreted by the adrenal medulla. Some receptors such as HER2 are capable of ligand-independent activation when overexpressed or mutated. This leads to constitutive activation of the ...
A neurotransmitter can be thought of as a key, and a receptor as a lock: the same neurotransmitter can activate multiple types of receptors. Receptors can be classified broadly as excitatory (causing an increase in firing rate), inhibitory (causing a decrease in firing rate), or modulatory (causing long-lasting effects not directly related to ...
After release into the synaptic cleft, monoamine neurotransmitter action is ended by reuptake into the presynaptic terminal. There, they can be repackaged into synaptic vesicles or degraded by the enzyme monoamine oxidase (MAO), which is a target of monoamine oxidase inhibitors, a class of antidepressants. [citation needed]