axon

(redirected from axon terminals)
Also found in: Dictionary, Thesaurus, Medical.

axon:

see nervous systemnervous system,
network of specialized tissue that controls actions and reactions of the body and its adjustment to the environment. Virtually all members of the animal kingdom have at least a rudimentary nervous system.
..... Click the link for more information.
; synapsesynapse
, junction between various signal-transmitter cells, either between two neurons or between a neuron and a muscle or gland. A nerve impulse reaches the synapse through the axon, or transmitting end, of a nerve cell, or neuron.
..... Click the link for more information.
.

Axon

 

a neurite, or axis cylinder; the process of a nerve cell along which neural impulses proceed from the cell body to innervated organs and other nerve cells.

Only one axon branches off each neuron, or nerve cell. The nutrition and growth of the axon depends on the neuron body; upon transection of the axon, its peripheral portion dies, but the central portion preserves its viability. Large animals possess axons—for example, those proceeding from the spinal cord to the extremities—that may reach a length of one meter or more when their diameter is several millimicrons (mμ). In some animals—for example, squid and fish—huge axons are found which measure hundreds of mμ in thickness. In axoplasm—that is, the protoplasm of axons—there are extremely thin fibrils, known as neurofibrils, as well as mitochondria and the endoplasmic network. Depending on whether axons are covered with a myelic (fatty) membrane or not, they are known as medullated or nonmedullated nerve fibers. The structure of the membranes and the diameters of the axons that constitute the nerve fiber are the factors that determine the rate of stimulus transmission along the nerve. The terminal sections of the axon, or terminals, branch off and make contact with other nerve, muscle, and gland cells. Stimuli are transmitted through these contact points, which are known as synapses. A nerve is a collection of axons.

axon

[′ak‚sän]
(neuroscience)
The process or nerve fiber of a neuron that carries the unidirectional nerve impulse away from the cell body. Also known as neuraxon; neurite.
References in periodicals archive ?
Graphic results of discriminant analysis showing the separation of axon terminals from secondary somatosensory area (S2), parietal rhinal area (PR), parietal ventral area (PV) and contralateral primary somatosensory area (S1c) into two distinct groups: Group I axons (black dots) and Group II Axons (red dots).
Hierarchical cluster analysis (HCA) dendrogram showing that feedforward axon terminals from S1 can be separated into two groups (I and II) in secondary somatosensory area (S2) (A, B), parietal ventral area (PV) (C, D), parietal rhinal area (PR) (E, F) and contralateral primary somatosensory area (S1c) (G, H).
Representative examples of digitally reconstructed axon terminals in secondary somatosensory area (S2), parietal rhinal area (PR), parietal ventral area (PV) and contralateral primary somatosensory area (S1c).
Number of primary somatosensory area (S1) feedforward fragments axon terminals to secondary somatosensory area (S2), parietal ventral area (PV), parietal rhinal area (PR) and contralateral primary somatosensory area (S1c) reconstructed from each case of neuronal tract tracing S1 microinjections in a total of n=8 animals.
Individual axons were followed up to their entry into the grey matter, and individual terminal branches arborizing into target cortical areas were finally selected for computer-assisted 3D reconstruction on the basis of the following criteria: absence of branching points previous to entry in the target cortex (with the exception of the cut end of the thicker parental branch) and the entire arbor of the axon terminal should appear to be contained within a single thick section.
This drug acts on alpha-2 adrenergic receptors and serotonin receptors on the presynaptic membrane (the axon terminal).
These opioid peptide-containing vesicles often are found in the same axon terminals with the smaller diameter, small molecule-containing vesicles, and thus many neurons have the capacity to release both small molecule and opioid peptide neurotransmitters (Kandel et al.
The endocannabinoids often are produced by postsynaptic neuronal elements and act on their cognate receptors, cannabinoid 1 (CBI) receptors, which are found almost exclusively on presynaptic axon terminals in the brain.
A specialized structure at the tip of the axon of the presynaptic neuron, termed the axon terminal, contains small packets known as vesicles, which are filled with neurotransmitter molecules.
Thus, at synapses using ligand-gated channels, the time between action potential depolarization (1) of the axon terminal and the beginning of the current flowing through the postsynaptic LGIC is a matter of 1 to 2 milliseconds.
Most of the neurotransmitter molecules discussed above are synthesized within the axon terminal itself and are then delivered into the vesicles waiting near the presynaptic release sites.