The basic building block of neuroscience, and dare I say psychology
Conclusion
The neuron and nervous system are essential to understand brain and body function. Psychology studies the larger-scale effects of brain activity, but close study of the biological and anatomical building blocks provide a smaller-scale viewpoint as well. Just as when repairing a computer, it’s important to understand the functions as well as the parts that make it up.
The greater nervous system
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central nervous system (CNS) and peripheral nervous system
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diff: cns is brain/spinal cord, peripheral is everything else
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periphery
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nerve fibers surrounded by connective tissue called endoneurium
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these fibers grouped into fascicles
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fascicles surrounded by perineurium
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peri: made up on connective tissue arranged in “lamellar manner” (clarify)
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Neuron differentiation & functions
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receive & transmit info
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one or many dendrites, differing per function
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functions
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afferent signaling
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protein synthesis involvement
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independent signaling functions w/other neurons
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first, second, and third-order neurons
Neuron communication
Neurons meet at synapses, junctions at which neurons connect with each other or the cells they take effect on. There are other types of junctions as well—for instance, neuroeffector junctions connect neurons to effector organs such as muscles that the signals from the nerves can activate (Ludwig et al., 2023).
As previously mentioned, neurons may use both electrical and chemical components to transmit a signal, though not all neurons use both. Some neurons use purely electrical signals, meeting at electrical synapses, and others have been found to use entirely mechanical methods of communication.
The myelin sheath–covered segments, called internodes, are coated in myelin for the purpose of speeding up the rate of transmission (of the electrical signal). The myelin acts as an electrical insulator, alike to an insulator jacket on the cables of electrical appliances (Grider et al., 2019).
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The structure of the neuron in detail (Urry et al., 2020)
Grider, M. H., Belcea, C. Q., Covington, B. P., & Sandeep Sharma. (2019, June 28). Neuroanatomy, Nodes of Ranvier. Nih.gov; StatPearls Publishing.
https://www.ncbi.nlm.nih.gov/books/NBK537273/
Ludwig, P. E., Reddy, V., & Varacallo, M. (2023, July 24). Neuroanatomy, Neurons. PubMed; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK441977/
Rolak, L. A. (2010). Neurology secrets. Mosby/Elsevier.
Thau, L., Singh, P., & Reddy, V. (2022, October 10). Anatomy, Central Nervous System. PubMed; StatPearls Publishing.
https://www.ncbi.nlm.nih.gov/books/NBK542179/
Urry, L., Cain, M., Wasserman, S., Minorsky, P., & Orr, R. (2020). Campbell Biology. Pearson.
Introduction
The neuron is the smallest functional unit of the nervous system, transporting signals throughout organisms with chemical and electrical methods. From their discovery and development throughout the 19th and 20th centuries to the close studies of the 21st century, they’ve remained essential topics of study in order to understand the full functioning of the brain and nervous system overall.
Anatomy of a neuron
A neuron is made up of a soma (cell body), axon, and dendrites. The soma holds the nucleus and organelles, as the cell bodies of other cell types do. The axon transmits electron signals and ends in an axon terminal, which converts the electric signal (action potential) into a chemical signal (neurotransmitters, neuromodulators, or neurohormones) and releases that chemical signal. In the next neuron, dendrites receive that signal and continue to transmit it onward. In addition, dendrites receive information not just from other neurons but from the surroundings as well (Ludwig et al., 2023).
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The mechanism of the nervous system (Urry et al., 2020)
Axons may be coated by myelin sheaths, an extension of the plasma membrane rich in lipids that surrounds the length of the axon with regularly spaced gaps in the material called nodes of Ranvier. These nodes tend to be approximately one nanometer in length (Grider et al., 2019). The nodes allow for saltatory conduction, in which an electrical signal “jumps” from node to node, increasing velocity of transfer (Rolak, 2010).
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