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Axon terminals (also called terminal boutons, synaptic boutons, end-feet, or presynaptic terminals) are distal terminations of the branches of an axon. An axon, also called a nerve fiber, is a long, slender projection of a nerve cell that conducts electrical impulses called action potentials away from the neuron's cell body to transmit those ...
When an action potential fires at the dendritic spine where the action potential is initiated from the presynaptic terminal to the post synaptic terminal. This action potential is then carried down the length of the dendrite and then is propagated down the length of the axon in order to get the presynaptic terminal to then perpetuate the ...
Postsynaptic potentials occur when the presynaptic neuron releases neurotransmitters into the synaptic cleft. These neurotransmitters bind to receptors on the postsynaptic terminal, which may be a neuron , or a muscle cell in the case of a neuromuscular junction . [ 1 ]
This prevents interaction between the acetylcholine released by the presynaptic terminal and the receptors on the postsynaptic cell. In effect, the opening of sodium channels associated with these acetylcholine receptors is prohibited, resulting in a neuromuscular blockade, similar to the effects seen due to presynaptic neurotoxins.
This depolarizing current reaches the presynaptic terminal, and the membrane depolarization that it causes there initiates the opening of voltage-gated calcium channels present on the presynaptic membrane. There is high concentration of calcium in the synaptic cleft between the two participating neurons (presynaptic and postsynaptic). This ...
The presynaptic axon terminal, or synaptic bouton, is a specialized area within the axon of the presynaptic cell that contains neurotransmitters enclosed in small membrane-bound spheres called synaptic vesicles (as well as a number of other supporting structures and organelles, such as mitochondria and endoplasmic reticulum).
One model of the tripartite synapse shows the presynaptic and postsynaptic terminals lying adjacent to each other, which the astrocyte is wrapped around the postsynaptic terminal. [1] However, localization and spatial distribution of the three elements of the tripartite synapse vary in different regions of the brain.
The repeated additions to the axon terminal membrane would eventually result in the uncontrolled growth of the axon terminal, which could lead to disastrous breakdown of the synaptic complex. The axon terminal compensates for this problem by reuptaking the vesicle by endocytosis and reusing its components to form new synaptic vesicles. [1]