Biological junctions through which neurons' signals can be sent
This article is about chemical synapses of the nervous system. For general information, see synapse. For other uses, see synapse (disambiguation).
Artistic interpretation of the major elements in chemical synaptic transmission. An electrochemical wave called an action potential travels along the axon of a neuron. When the action potential reaches the presynaptic terminal, it provokes the release of a synaptic vesicle, secreting its quanta of neurotransmitter molecules. The neurotransmitter binds to chemical receptor molecules located in the membrane of another neuron, the postsynaptic neuron, on the opposite side of the synaptic cleft.
Chemical synapses are biological junctions through which neurons' signals can be sent to each other and to non-neuronal cells such as those in muscles or glands. Chemical synapses allow neurons to form circuits within the central nervous system. They are crucial to the biological computations that underlie perception and thought. They allow the nervous system to connect to and control other systems of the body.
At a chemical synapse, one neuron releases neurotransmitter molecules into a small space (the synaptic cleft) that is adjacent to another neuron. The neurotransmitters are contained within small sacs called synaptic vesicles, and are released into the synaptic cleft by exocytosis. These molecules then bind to neurotransmitter receptors on the postsynaptic cell. Finally, the neurotransmitters are cleared from the synapse through one of several potential mechanisms including enzymatic degradation or re-uptake by specific transporters either on the presynaptic cell or on some other neuroglia to terminate the action of the neurotransmitter.
The adult human brain is estimated to contain from 1014 to 5 × 1014 (100–500 trillion) synapses.[1] Every cubic millimeter of cerebral cortex contains roughly a billion (short scale, i.e. 109) of them.[2] The number of synapses in the human cerebral cortex has separately been estimated at 0.15 quadrillion (150 trillion)[3]
The word "synapse" was introduced by Sir Charles Scott Sherrington in 1897.[4] Chemical synapses are not the only type of biological synapse: electrical and immunological synapses also exist. Without a qualifier, however, "synapse" commonly refers to chemical synapses.
^Drachman D (2005). "Do we have brain to spare?". Neurology. 64 (12): 2004–5. doi:10.1212/01.WNL.0000166914.38327.BB. PMID 15985565. S2CID 38482114.
Chemicalsynapses are biological junctions through which neurons' signals can be sent to each other and to non-neuronal cells such as those in muscles...
In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to...
at a chemicalsynapse. In many[specify] animals, electrical synapse-based systems co-exist with chemicalsynapses. Compared to chemicalsynapses, electrical...
from the presynaptic axon terminal into the synaptic cleft, as in a chemicalsynapse. The excitatory neurotransmitters, the most common of which is glutamate...
neighboring cells through electrical synapses or cause chemicals called neurotransmitters to be released at chemicalsynapses. A cell that receives a synaptic...
The squid giant synapse is a chemicalsynapse found in squid. It is the largest known chemical junction in nature. The squid giant synapse (Fig 1) was first...
signal is the postsynaptic neuron or cell. Synapses can be either electrical or chemical. Electrical synapses are characterized by the formation of gap...
synaptic components to the production of activity at the chemicalsynapse. Tripartite synapses occur at a number of locations in the central nervous system...
rapid non-chemical-mediated transmission. Rectifying channels ensure that action potentials move only in one direction through an electrical synapse.[citation...
A neuromuscular junction (or myoneural junction) is a chemicalsynapse between a motor neuron and a muscle fiber. It allows the motor neuron to transmit...
Dendrodendritic synapses are connections between the dendrites of two different neurons. This is in contrast to the more common axodendritic synapse (chemical synapse)...
postsynaptic dendrite or cell body, and travels "backwards" across a chemicalsynapse to bind to the axon terminal of a presynaptic neuron. Retrograde signals...
muscles or glands. Chemical synapse Gap junction Synaptic plasticity Long-term potentiation Neurotransmitter – endogenous chemical that relays, amplifies,...
is defined as monosynaptic, referring to the presence of a single chemicalsynapse. In the case of peripheral muscle reflexes (patellar reflex, achilles...
distinct from direct communication systems like electrical synapses and chemicalsynapses. The phrase may refer to the coupling of adjacent (touching)...
communicate with other cells via synapses, which are specialized connections that commonly use minute amounts of chemical neurotransmitters to pass the electric...
nerve synapse) needs to form between two cells before they can grow to form a unidirectional chemical nerve synapse. The chemical nerve synapse is the...
changes in the membrane potential of the postsynaptic terminal of a chemicalsynapse. Postsynaptic potentials are graded potentials, and should not be confused...
range of tissues such as the adherens junction of epithelia or the chemicalsynapse of the neuronal tissue. So far four nectins have been identified in...
of chemicalsynapse that differs both in structure and function from the chemicalsynapses that connect neurons to each other. Both types of synapses rely...
special case of paracrine signaling (for chemicalsynapses) or juxtacrine signaling (for electrical synapses) between neurons and target cells. Many cell...
directly to the effector organ skipping both an integration center and a chemicalsynapse present in the spinal cord reflex. The impulse is limited to a single...
signaling molecule secreted by a neuron to affect another cell across a synapse. The cell receiving the signal, or target cell, may be another neuron,...
he determined that the complex enzyme cycle was easily disrupted. Chemicalsynapse Quantal neurotransmitter release End-plate potential List of refugees...
acid which is able to transmit a nerve message across a synapse. Neurotransmitters (chemicals) are packaged into vesicles that cluster beneath the axon...
signaling is a form of cell signaling in which a cell secretes a hormone or chemical messenger (called the autocrine agent) that binds to autocrine receptors...
Fromherz, Peter (29 August 2003). "Neuron-Semiconductor Chip with ChemicalSynapse between Identified Neurons". Physical Review Letters. 92 (3): 038102...
or gland cells – at junctions called synapses. In some circumstances, the axon of one neuron may form a synapse with the dendrites of the same neuron...
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