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In the nervous system, a synapse [1] is a structure that allows a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or a target effector cell. Synapses can be classified as either chemical or electrical, depending on the mechanism of signal transmission between neurons.
Once at the synapse, synaptic vesicles are loaded with a neurotransmitter. Loading of transmitter is an active process requiring a neurotransmitter transporter and a proton pump ATPase that provides an electrochemical gradient. These transporters are selective for different classes of transmitters.
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 ...
Synapses are the key functional elements of the brain. [11] The essential function of the brain is cell-to-cell communication, and synapses are the points at which communication occurs. The human brain has been estimated to contain approximately 100 trillion synapses; [12] even the brain of a fruit fly contains several million. [13]
Axon terminals are specialized to release neurotransmitters very rapidly by exocytosis. [1] Neurotransmitter molecules are packaged into synaptic vesicles that cluster beneath the axon terminal membrane on the presynaptic side (A) of a synapse.
Most famous parts of the brain highlighted in different colours The human brain anatomical regions are ordered following standard neuroanatomy hierarchies. Functional , connective , and developmental regions are listed in parentheses where appropriate.
A diagram of the proteins found in the active zone. The active zone is present in all chemical synapses examined so far and is present in all animal species. The active zones examined so far have at least two features in common, they all have protein dense material that project from the membrane and tethers synaptic vesicles close to the membrane and they have long filamentous projections ...
A dendritic spine (or spine) is a small membrane protrusion from a neuron's dendrite that typically receives input from a single axon at the synapse.Dendritic spines serve as a storage site for synaptic strength and help transmit electrical signals to the neuron's cell body.