Nerve
Manoj Ramachandran, Tom Nunn in Basic Orthopaedic Sciences, 2018
Neurons specialize in sending and receiving chemically-mediated electrical signals. The functional unit of a nerve is the neuron; it has a cell body (perikaryon) and an axon. The axolemma (cell membrane) encloses the axoplasm (cytoplasm). The cell body contains all the subcellular organelles found in a typical cell but is specialized to provide high levels of protein synthesis, by having densely packed ribosomes on the rough endoplasmic reticulum. Dendrites are extensions of the cell body and receive signals from other neurons. Each neuron generally has a single axon arising from the cell body that typically conducts impulses away from the cell body. This may be encapsulated in a myelin sheath (Figure 11.1).
Clinical and electrodiagnostic evaluations of the peripheral nervous system
James W. Albers, Stanley Berent in Neurobehavioral Toxicology: Neurological and Neuropsychological Perspectives, 2005
What comprises the peripheral nervous system? Basically, the peripheral nervous system is made up of motor, autonomic, and sensory neurons whose axons extend or originate outside of the central nervous system. Muscle fibers innervated by motor axons are also considered part of the peripheral nervous system. The neuron is the fundamental unit of the nervous system, central or peripheral. It consists of a cell body, axon, and dendrites. The axon is a cytoplasmic extension of the cell body. The axon’s fundamental role involves transmission of information from the cell body to other neurons, muscle fibers, or glands. Dendrites are protoplasmic processes of the nerve cell that transmit information from other axons to the neuron cell body. In the peripheral nervous system, Schwann cells encircle unmyelinated axons and form the myelin sheath surrounding myelinated fibers. The nervous system transmits information from one place to another using electrochemical signals. Included among the electrochemical signals are nerve or muscle action potentials, depending on the tissue of origin. Action potentials can be activated volitionally, as part of a reflex response, or by external application of electrical stimulation. The clinical electrodiagnostic examination records this electrical activity, and the results are used to make decisions about whether the physiological activity is normal or abnormal.
Neural Networks for Medical Image Computing
K. Gayathri Devi, Kishore Balasubramanian, Le Anh Ngoc in Machine Learning and Deep Learning Techniques for Medical Science, 2022
The neural network functions similarly to the network model of the human brain. The comparison of Biological Neural Network and Artificial Neural Network is shown in Table 4.1. In the biological cell, the neuron performs the function of processing information. It has wires like structures through which the neurons transmit and receive information. There are huge numbers of neurons with numerous interconnections. The biological neurons are comprised of soma, dendrites, synapses, and axon. The dendrites are those wire-like structures that receive information from various neurons that are present in a network. The soma receives the information from dendrites and passes it to the axon. The nerve fiber through which electrical signals travel from one neuron to another is called as axon. Synapses are small gaps that transmit signal between the neurons. It connects the axons to the dendrites. The neuron processes the information based on the architecture of the network.
Rab11-mediated recycling endosome role in nervous system development and neurodegenerative diseases
Published in International Journal of Neuroscience, 2021
Jiajia Zhang, Gang Su, Qionghui Wu, Jifei Liu, Ye Tian, Xiaoyan Liu, Juanping Zhou, Juan Gao, Wei Chen, Deyi Chen, Zhenchang Zhang
Dendrites are the main structure of receiving information in neurons. The complexity of dendrites affects the connectivity of neurons, which is essential for the maintenance of normal brain function [38]. Rab11 plays an important role in promoting dendritic arborization through endosome recycling [18, 19]. As we all known, BDNF and its TrkB receptor are extracellular signaling molecules that can induce dendritic branches [20, 21]. BDNF enhanced the activity of Rab11 and induced the aggregation of vesicles carrying Rab11 and TrkB receptors in dendrites, which increased the sensitivity of BDNF and promoted dendritic branches [21–23]. In addition, it has been reported that the stage of TrkB receptors localized to Rab11-positive endosomes is regulated by Rab11-interacting protein (FIP3) [24]. Intriguingly, Slit- and NTRK-like family5(Slitrks5) acting as a TrkB co-receptor facilitates Rab11-FIP3 recruitment of TrkB receptors to Rab11 compartments [39].
Tailoring synthetic polymeric biomaterials towards nerve tissue engineering: a review
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Hamed Amani, Hanif Kazerooni, Hossein Hassanpoor, Abolfazl Akbarzadeh, Hamidreza Pazoki-Toroudi
Owing to intricate tasks and even supporting the most daily living functions, the CNS possesses a high degree of anatomical complexity [26]. The PNS is formed from peripheral, cranial (arising from the brain) and spinal nerves as well as their motor and sensory endings. A multilayered building containing bone, meninges, connective tissue and skin support the nervous system. In fact, the spinal cord acts as a bridge for connecting the brain to the rest of the body and facilitates receiving and sending sensory and motor information via electrochemical impulses to and from the PNS [27]. There are two types of cells within the nerve system including neurons and neuroglia. Neurons are known as the basic structural and functional components of the nervous system and are comprised of soma, axons, and dendrites. Dendrites provide the possibility for transmission of electrical signals to soma and axons steer impulses away. Glial cells, or neuroglia act as supporting cells for neuronal function and are classified into three type cells including astrocytes, oligodendrocytes (present in the CNS) and Schwann cells (present in the PNS). The amount of glial cells is more than neurons in the nervous system. Although neurons are not capable to perform mitosis, glial cells have the ability in cell division. It is also worth to note that neurons can rehabilitate or trigger sprouting in certain conditions. The spinal cord is comprised of dendrites, axons, and cell bodies.
Dynamic alteration of dendrites and dendritic spines in the hippocampus and microglia in mouse brain tissues after kainate-induced status epilepticus
Published in International Journal of Neuroscience, 2021
Lingling Xie, Tianyi Li, Xiaojie Song, Hong Sun, Jie Liu, Jing Yang, Wenjie Zhao, Li Cheng, Hengsheng Chen, Benke Liu, Wei Han, Chen Yang, Li Jiang
As major sites of excitatory synaptic input into the CNS, dendritic spines are strongly implicated in the mechanisms of plasticity and learning [6]. Furthermore, both clinical and experimental studies have indicated that epilepsy-related loss and structural injury of dendritic spines may be associated with cognitive deficits [7–9]. Recent evidence has confirmed the existence of communication between the microglia and neurons in epilepsy [10]. Activated microglia may exert different effects on brain function depending on the phase of epileptogenesis [11], and correct timing of the modulation of microglial phenotypes can improve the outcomes in epilepsy [12]; however, this requires further exploration. In addition, reports of the dynamic alteration in microglial types, their markers and changes in dendritic spines in the hippocampus of epileptic models at different time-points after acute status epilepticus (SE) are rare.
Related Knowledge Centers
- Action Potential
- Axon
- Axon Terminal
- Dendritic Spine
- Neurotransmission
- Pyramidal Cell
- Synapse
- Soma
- Neuron
- Excitatory Synapse