Axon, a projection from a neuron.The length of axons can vary greatly among different types of neurons, with the length of longer axons reaching more than one meter, and the length of shorter axons only around the cell body.The cytoplasm in the axon is called axoplasm, which is similar to the cell body except for Nissl.Even if the axon is very long, its thickness is uniform except near the end.Axons send out lateral branches at right angles.Axons repeatedly branch near the end, and the end can form a terminal buckle or foot in the center, forming a synapse with the surface of another neuron;In the periphery, various types of nerve endings can be found.Axons transmit impulses from neurons.
Axons are also called axons.Either of two processes of a neuron.Each neuron has only one axon, usually composed ofCell bodyissue.It is usually thinner than the dendrites, with uniform diameter, smooth surface, few branches, and often extends out of the lateral branches at right angles to the axons.There are many branches at the end of axon, forming axon terminals.The axon surface is surrounded by a film, which is called "axon membrane".There is axial slurry in the membrane, containingmitochondrion, microfilaments and microtubules.Nerve secretion can be transported to the end of axon through axoplasmic flow.
nerve cellThe elongated processes that protrude from the cytoplasm are called axons.The diameter of axons is generally the same in the whole length, with few branches. Some send out collateral branches at right angles to connect with other neurons, which can expand the range of efferent excitation.The end of axon repeatedly branches, called terminal branch.The number, form and distribution of the branches of the terminal tree technology are different, and finally attach to the dendrites of other cell bodies.There is a film on the surface of the axon, called the axon membrane, which is closely related to the ion permeability of nerve excitation conduction and is of great significance in electrophysiology.Except that there is no Nissl body in the axon, other components are roughly the same as those in the cytoplasm.The main function of axons is to transmit excitatory impulses generated by cell bodies, and transmit the impulses to other neurons or effectors of muscle and gland cells.
Anatomical structure and function of axon
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Axon: All neurons have only one axon. When it is emitted from the cell body, its starting part is conical, called the axon. The rest of the length is relatively constant in thickness.Slender, smooth surface, few branches, generally only a few collateral branches, and axons at right angles.There are many terminal branches, which are called terminal branches.The axon ends form synapses with dendrites or cell bodies of other neurons or directly reach effectors.The length of axon is related to the type of neuron. The short one is only a few microns, and the long one can reach more than 1 meter.The main differences between the axon and the dendrite, except for the difference in shape and direction of impulse conduction, were observed under the light microscope, and there was no Nissl body in the axon.The cell membrane of the axon is called the axon membrane, and there is generally no transmitter receptor on it except for individual parts.At the end of the terminal branch of the axon, there are many vesicles containing neurotransmitters, which are called synaptic vesicles.The cytoplasm in the axon is called axoplasm, and there is no ribosome in it, so it cannot produce proteins.The nerve filaments and microtubules in the axons are constantly updated. These new structures are constantly formed in the cell body and then enter the axons. The old structures are constantly decomposed at the axon terminals.Nerve filaments and microtubules form a network in the axon, and move from the axon to the end of the axon, which is called axonal (axoplasma) flow, and participate in the material transport in the axon.
The main function of axon is to transmit the excitatory impulse generated by neuron cell body to other neurons or effectors.
Axon related diseases
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1. Nerve axon break: The appearance of nerve axon break is still continuous and normal, but part or most of the nerve axon break, and its inner membrane is complete, which may also be damaged, and the nerve conduction function is lost.It is often caused by injury or strain.The clinical manifestations are atrophy of muscles innervated by injured nerves, disappearance of corresponding tendon reflexes, complete loss of various senses in the assigned area, and concurrent irritation symptoms, such as hyperalgesia or severe burning pain.There are also autonomic dysfunction in the corresponding areas, such as hyperhidrosis.Treatment: physiotherapy, electric stimulation, acupuncture, functional sports and neuromuscular nutrition drugs, such as B vitamins, dibazol, adenosine triphosphate, etc.The prognosis is relatively good.
2. Diffuse axonal injury: there are small oval limited abnormalities in the white matter nerve bundle of the brain, which are more common.As the damaged shear stress acts on the axon, the function of axon is lost due to traction, and the function of impulse transmission is blocked.Generally, there is no fracture, brain contusion or increased intracranial pressure, but it can cause coma or even death.
