Cells, Tissues and Organs
David Sturgeon in Introduction to Anatomy and Physiology for Healthcare Students, 2018
The final type of tissue is nervous tissue (not in the ‘worried’ sense). Nervous tissue comprises nerve cells (neurons) that generate, transmit and receive electrical impulses (action potentials), and supporting cells (glial cells) that nourish and protect the nerve cells. The two functions are often expressed as excitable and non-excitable. Nerve cells are highly specialised in their function and vary greatly in length. However, they still exhibit many of the same characteristics as other cells (e.g. nucleus, mitochondria, cytoplasm, etc.) and require oxygen and glucose to produce cellular energy (ATP). In this sense, they are susceptible to the same challenges as other, less-specialised cells and a few more besides. One interesting feature of ‘excitable’ neurons is that, for the most part, they are unable to undergo mitosis following maturation. Supporting cells, on the other hand, are capable of dividing mitotically and are essential for the maintenance of their more excitable neighbours. There are a number of different types of glial cells including astrocytes (cellular repair and clearance of neurotransmitters), microglia (clearance of cellular debris), oligodendrocytes and schwann cells (both produce an insulating material called myelin). However, we will look in much more detail at how neurons and glial cells work in Chapter 12.
Biological Basis of Behavior
Mohamed Ahmed Abd El-Hay in Understanding Psychology for Medicine and Nursing, 2019
Nervous tissue is composed of two types of cells: neurons and glial cells. Neurons are the primary type of cells whose function is to receive and transmit information. They are responsible for the computation and communication that the nervous system provides. Glial cells or glia play a supporting role for nervous tissue. Neurons are composed of: (1) a cell body that contains the nucleus and most of the cell’s biosynthetic machinery and keeps the cell alive; (2) branching tree-like fibers called dendrites, which extend from the cell body, collect information from other cells and send the information to the cell body; (3) an axon, which transmits information away from the cell body to other neurons or to the muscles and glands; and (4) specialized regions, at the end of axons, called synaptic buttons or synaptic endings, where communication with other nerve cells or special effector tissues (such as gland or muscle cells) is carried out (Figure 5.2).
The cell and tissues
Peate Ian, Dutton Helen in Acute Nursing Care, 2020
Nervous tissue is composed of two main types of cell (see Figure 3.14). Neurons are the cells that conduct signals very rapidly to and from the central nervous system. They are primarily composed of a cell body and long extensions called axons. Either at one end of the axon or on the cell body are a number of other projections, called dendrites. Neurons conduct impulses in one direction only. The impulses arrive at the dendrites and are then passed along the axon, never the other way round. Unlike many other tissues, the neurons do not touch each other: there is always a small gap known as a synapse between them. The electrical impulse that passes along the axon stimulates the release of chemicals that pass across the synapse to stimulate an electrical impulse in the next neuron. This works as a safety and control mechanism. If the neurons were actually in contact with each other, the whole nervous system could be affected every time one neuron were stimulated.
Mechanical characteristics of BMSCs-intervened sciatic nerve in chronic alcohol-intoxicated animal model
Published in International Journal of Neuroscience, 2021
Peng Li, Yudong Chen, Kun Yang, Dachuan Chen, Daliang Kong
Peripheral neuropathy is a common neurological damage caused by chronic alcoholism. Studies have shown that neurotoxins first attack the axonal transport system, which transports the essential proteins and other cellular components synthesized by the cell body to the peripheral axon terminals; because the regeneration of structural and functional proteins in the axons depends on cell synthesis and axonal transport, axons’ not being able to synthesize such proteins may thereby induce peripheral neuropathy [18]. Morphological observation of sciatic nerve tissue of each group showed that the sciatic nerve fibers in group CA were arranged in disorder, axons swelled and thickened, together with axonal atrophy and even disappeared, segmental myelin loss, cell edema, loose intercellular structure, and disorderly arranged dorsal root ganglion neurons, indicating that the morphological changes of the sciatic nerve happened. In group CA-BMSCs, most of the sciatic nerve fibers were arranged in order, and the tissue morphology was restored. In group CA-bFGF, the tissue morphology of sciatic nerve was also restored, indicating that the intervention of BMSCs and bFGF have certain effects on the recovery of the sciatic nerve morphology, and the effects of BMSCs are better.
Development of polypyrrole/collagen/nano-strontium substituted bioactive glass composite for boost sciatic nerve rejuvenation in vivo
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Bo Lin, Guoqing Dun, Dongzhu Jin, Yaowu Du
Nerve tissue engineering is a promising methodology that can possibly address this need with engineered nerve channels. There has been a huge exertion devoted to creating manufactured nerve courses that have brought about empowering recovery and some level of utilitarian recuperation of fringe nerve defects [1–5]. Though, more materials should be done to improve their adequacy contrasted with standard nerve grafts. A significant part of engineered nerve unites is their capacity to direct power. Electrical incitement can essentially advance the recovery of fringe nerve wounds in the wake of looking at an extensive number of creature tests [6]. In this manner, there has been an extensive spotlight on the utilization of conductive substances in neural tissue designing. Scientists want to build up a novel substance that can fulfil both the conductivity needs of nerve tissue and the necessities of tissue designing all in all. Preferably, this course ought to be degradable, cyto-compatible and give a fitting electrical condition.
Ultrastructural evidence for presenсe of gap junctions in rare case of pleomorphic xanthoastrocytoma
Published in Ultrastructural Pathology, 2020
Evgeniya Yu. Kirichenko, Sehweil Salah M. M., Zoya A. Goncharova, Aleksei G. Nikitin, Svetlana Yu. Filippova, Sergey S. Todorov, Marina A. Akimenko, Alexander K. Logvinov
Despite the rarity of PXA, a large amount of data concerning the features of the cellular structure of this type of tumor has been accumulated. Nevertheless, the characteristics of intercellular communication in PXA are poorly studied. To date, only a few descriptions of desmosome-like contacts have been obtained.11,12 At the same time, the existence of gap junctions and half-channels, as well as the expression of their constituent proteins in astrocytic tumors, is an urgent topic in modern neurooncology.13–15 Gap junctions (GJ) are hexametric membrane pores, formed by connexins that directly connect cytoplasms of two cells. In nervous tissue, they can be formed either between neuronal cells16, or between astroglial and oligodendroglial cells.17 According to the modern data, GJs occupy a special place among the various types of intercellular contacts and serve as the key structural and functional component of metabolic homeostasis maintenance in the brain.18 The controversial role of GJ in astrocytic tumor pathogenesis has been investigated in a number of studies. On the one hand, GJ possesses such pro-oncogenic properties as tumor cells migration promotion19 and transmission of transforming signals from tumor to nonmalignant tissue.20 On the other hand, connexins proteins have been known for the antiproliferative activity.14