Axon

An Axon is a nerve component that is a long, slender projection of a vertebrate neuron that conducts electrical impulses known as action potentials away from the nerve cell body.

• AKA: Nerve Fiber.
• Context:
  • It is essential for transmitting electrical signals and enabling communication between different parts of the nervous system, allowing mammals to perceive and respond to the environment.
  • …
• Example(s):
  • Peripheral Nervous System: axons of motor neurons transmit signals from the spinal cord to muscles, causing them to contract and produce movement.
  • Sensory System: axons of sensory neurons transmit information about touch, temperature, pain, and other sensations from the skin, muscles, and internal organs to the brain for processing.
  • Central Nervous System: axons of neurons in the visual cortex of the brain transmit signals to other regions of the brain involved in processing visual information, enabling us to see and interpret the world around us.
  • …
• Counter-Example(s):
  • Cilia,
  • Dendrites.
• See: Human Brain, Neuron, Neural Network, Action Potential, Soma (Biology), Sensory Neuron, Pseudounipolar Neuron, Afferent Nerve Fiber, Peripheral Nervous System, Neurological Disorder, Central Nervous System.

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References

2023

• (ChatGPT-OpenAi, 2023) ⇒ https://chat.openai.com Retrieved:2023-4-23.
  • Q: What is an Axon?
  • A:An axon is a long, slender, thread-like projection of a nerve cell (neuron) that conducts electrical impulses away from the neuron's cell body, towards other neurons or effector cells (such as muscles or glands). The axon is typically covered by a myelin sheath, which helps to insulate the axon and increase the speed of electrical signal transmission.

     Axons can vary greatly in length, from just a few micrometers to more than a meter in some cases (such as the axons that run from the base of the spinal cord to the toes). Axons can also branch into smaller projections called axon terminals, which connect with other neurons or effector cells to form synapses, the junctions where neurotransmitters are released and electrical signals are transmitted from one cell to another.

    Overall, the axon is a crucial component of the nervous system, allowing for the rapid and precise communication between neurons and other cells that underlies much of our behavior and physiology.

2023b

• (Wikipedia, 2023) ⇒ https://en.wikipedia.org/wiki/axon Retrieved:2023-4-17.
  • An axon (from Greek ἄξων áxōn, axis), or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action potentials away from the nerve cell body. The function of the axon is to transmit information to different neurons, muscles, and glands. In certain sensory neurons (pseudounipolar neurons), such as those for touch and warmth, the axons are called afferent nerve fibers and the electrical impulse travels along these from the periphery to the cell body and from the cell body to the spinal cord along another branch of the same axon. Axon dysfunction can be the cause of many inherited and acquired neurological disorders that affect both the peripheral and central neurons. Nerve fibers are classed into three typesgroup A nerve fibers, group B nerve fibers, and group C nerve fibers. Groups A and B are myelinated, and group C are unmyelinated. These groups include both sensory fibers and motor fibers. Another classification groups only the sensory fibers as Type I, Type II, Type III, and Type IV.

    An axon is one of two types of cytoplasmic protrusions from the cell body of a neuron; the other type is a dendrite. Axons are distinguished from dendrites by several features, including shape (dendrites often taper while axons usually maintain a constant radius), length (dendrites are restricted to a small region around the cell body while axons can be much longer), and function (dendrites receive signals whereas axons transmit them). Some types of neurons have no axon and transmit signals from their dendrites. In some species, axons can emanate from dendrites known as axon-carrying dendrites. No neuron ever has more than one axon; however in invertebrates such as insects or leeches the axon sometimes consists of several regions that function more or less independently of each other.

    Axons are covered by a membrane known as an axolemma; the cytoplasm of an axon is called axoplasm. Most axons branch, in some cases very profusely. The end branches of an axon are called telodendria. The swollen end of a telodendron is known as the axon terminal which joins the dendron or cell body of another neuron forming a synaptic connection. Axons make contact with other cellsusually other neurons but sometimes muscle or gland cellsat junctions called synapses. In some circumstances, the axon of one neuron may form a synapse with the dendrites of the same neuron, resulting in an autapse. At a synapse, the membrane of the axon closely adjoins the membrane of the target cell, and special molecular structures serve to transmit electrical or electrochemical signals across the gap. Some synaptic junctions appear along the length of an axon as it extends; these are called en passant ("in passing") synapses and can be in the hundreds or even the thousands along one axon. Other synapses appear as terminals at the ends of axonal branches.

    A single axon, with all its branches taken together, can innervate multiple parts of the brain and generate thousands of synaptic terminals. A bundle of axons make a nerve tract in the central nervous system, and a fascicle in the peripheral nervous system. In placental mammals the largest white matter tract in the brain is the corpus callosum, formed of some 200 million axons in the human brain.

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