What Is an Axon?

Axon, a protrusion from a neuron. The length of axons can be very different in different types of neurons, the elderly can reach more than one meter, and the short ones are only around the cell body. The cytoplasm inside the axon is called axoplasm, which is similar to the soma except it does not contain Nissl. Even if the axon is very long, its thickness is uniform except near the tip. The axons flank at right angles. The axon branches repeatedly at the near end, and the end can form a terminal buckle or terminal foot in the center, forming a synapse with the surface of another neuron; in the surroundings, various types of nerve ending organs can finally be formed. Axons transmit impulses from neurons.

Axon, a protrusion from a neuron. The length of axons can be very different in different types of neurons, the elderly can reach more than one meter, and the short ones are only around the cell body. The cytoplasm inside the axon is called axoplasm, which is similar to the soma except it does not contain Nissl. Even if the axon is very long, its thickness is uniform except near the tip. The axons flank at right angles. The axon branches repeatedly at the near end, and the end can form a terminal buckle or terminal foot in the center, forming a synapse with the surface of another neuron; in the surroundings, various types of nerve ending organs can finally be formed. Axons transmit impulses from neurons.

Chinese name

Axon

Foreign name

Axon, neurite

Nature

science

Category

biological

Content

Neuron output channel

nickname

Axon

Axon Overview

Axons are also known as "axons". One of two types of neurons. Each neuron has only one axon, which is usually emitted by the cell body. Usually thinner than dendrites, uniform in diameter, smooth surface, fewer branches, often protruding side branches, at right angles to the axons. The axon end branches more, forming the axon terminal. The surface of the axon is surrounded by a thin film called the axon membrane. The membrane contains axons, which contain mitochondria, microfilaments, and microtubule bundles. Nerve secretions can be transported to the axon ends by axoplasmic flow.

The slender protrusion of nerve cell cytoplasm is called axon. The diameter of the axon is generally consistent throughout the entire length, and there are fewer branches. Some of the axons are sent at right angles to connect with other neurons, which can expand the range of outgoing excitement. The end of the axon branches repeatedly, called the terminal branch. The number, form and distribution of each final tree technique branch are different, and they are finally attached to the dendrites of other cell bodies. There is a thin film on the surface of the axon, called the axonal membrane, which is closely related to the ion permeability during nerve excitation conduction, and has important significance in electrophysiology. Except that there is no Nissl body inside the axon, other components are roughly the same as those in the cytoplasm. The main role of axons is to transmit excitatory impulses generated by the soma, and to transmit impulses to other neurons or to effectors of muscle and gland cells.

Anatomy of axon and its role

Axons: All neurons have only one axon. After they are emitted from the cell body, the starting part is conical, called the axon, and the remaining length is relatively constant. Slender, smooth surface, few branches, usually only a few side branches, at right angles to the axon. There are many terminal branches, which are called terminal branches. The axon ends form synapses with the dendrites or cell bodies of other neurons or reach the effector directly. The length of the axon is related to the type of neuron. The length of the axon is only a few microns, and the length can reach more than 1 meter. The main differences between axons and dendrites, except for the morphology and the direction of conducting impulses, are observed under light microscope. Axons do not contain Nissl bodies. The axon's cell membrane is called the axon membrane, and there are generally no receptors for transmitters except for individual parts. There are many neurotransmitter-containing vesicles at the end of the axon terminal branch, which are called synaptic vesicles. The cytoplasm inside the axon is called axoplasm, where there are no ribosomes and therefore cannot make proteins. The nerve filaments and microtubules in the axon are constantly updated. These new structures continue to form inside the axon and enter the axon. The old structures continue to break down at the axon's end. Nerve filaments and microtubules form a network frame in the axon, and they move from the axon to the end of the axon, which is called axonal (axoplasm) flow, and participates in the axonal material transport.

The main role of axons is to transmit the excitatory impulses generated by the neuron soma to other neurons or effectors.

Axon and axon-related diseases

1. Nerve axon rupture: Nerve axon rupture The nerve appearance is still continuous and normal, but some or most of the axon ruptures, the intima is intact, and the nerve conduction function may be damaged. Often caused by injury or stretch injury. The clinical manifestations are the atrophy of the innervated muscles and the disappearance of the corresponding tendon reflexes. The various sensations in the assigned area are completely lost, which can be accompanied by irritation symptoms such as hyperalgesia or severe burning pain. Autonomic dysfunction, such as hyperhidrosis, also occurs in the corresponding areas. Treatment: Mainly take physiotherapy, electrical stimulation, acupuncture, functional exercise and neuromuscular nutrition drugs, such as B vitamins, dibazole, adenosine triphosphate and so on. The prognosis is relatively good.

2. Diffuse axonal injury: There are small oval-shaped localized abnormalities in the white matter nerve bundles, which are more common. Because the damaged shear stress acts on the axon, it is stretched and loses its function, and the function of transmitting impulse is blocked. It is generally not accompanied by fractures, brain contusions or increased intracranial pressure, but can cause coma and even death.