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Neuromuscular Physiology
Published in Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan, Strength and Conditioning in Sports, 2023
Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan
The muscle fiber is surrounded by the sarcolemma (see below) and contains the sarcoplasm (cytoplasm) of muscle cells, a semifluid made up of water, minerals, proteins, and several other substances. Suspended in the sarcoplasm are various organelles, which are subcellular structures that can have one or multiple specific functions. Organelles include nuclei, mitochondria, cytoskeletal and cytotubular network systems, Golgi bodies, glycogen granules, lipid vacuoles, etc. Generally, muscle cell proteins can be grouped into four categories: (i) granules plus an organelle, (ii) stroma and sarcolemmal, (iii) myofibrillar, and (iv) sarcoplasmic (80, 125, 127). The spaces between myofibrils contain the sarcoplasmic proteins and include myoglobin and glycolytic enzymes.
Muscle and Nerve Histology
Published in Maher Kurdi, Neuromuscular Pathology Made Easy, 2021
The sarcoplasm contains multiple organelles including mitochondria, sarcoplasmic reticulum, Golgi apparatus, microtubules, glycogens, ribosomes, lipid droplets, and myofibrils. The mitochondria are located at the level of the I-band. They present in type I fibers more than type II fibers, but this is not considered a consistent distinguishing feature.
Mechanotransduction Mechanisms of Hypertrophy and Performance with Resistance Exercise
Published in Peter M. Tiidus, Rebecca E. K. MacPherson, Paul J. LeBlanc, Andrea R. Josse, The Routledge Handbook on Biochemistry of Exercise, 2020
Andrew C. Fry, Justin X. Nicoll, Luke A. Olsen
The integration of the nervous system on the mechanosensory properties of skeletal muscle is less frequently investigated. Motor unit firing during excitation–contraction coupling results in the release of intracellular calcium into the sarcoplasm, which causes actin–myosin cross-bridging to occur and the resulting shortening of the sarcomere and the production of force. The release of calcium into the sarcoplasm increases the phosphorylation of numerous intracellular signalling pathways, including calmodulin and MAPK cascades.
Solanaceae glycoalkaloids: α-solanine and α-chaconine modify the cardioinhibitory activity of verapamil
Published in Pharmaceutical Biology, 2022
Szymon Chowański, Magdalena Winkiel, Monika Szymczak-Cendlak, Paweł Marciniak, Dominika Mańczak, Karolina Walkowiak-Nowicka, Marta Spochacz, Sabino A. Bufo, Laura Scrano, Zbigniew Adamski
Calcium ions are crucial for the contraction of all types of muscles. After influx into the cytoplasm, they interact with myofilaments and ultimately allow for interaction between myosin and actin filaments, and thus for muscle contraction. Since they are a trigger and an executor of muscle contractions, their concentration in the sarcoplasm must be strictly regulated. In striated muscles, cell membrane depolarization is a signal that initiates the cascade responsible for muscle contraction. Changes in the cell membrane potential activate and open the L-type calcium channels. Then, the local increase in Ca2+ concentration activates the ryanodine receptor, a sarcoplasmic calcium channel, which releases the next portion of calcium ions into the cytoplasm, which interacts with myofilaments.
Vitamin D3 intake as modulator for the early biomarkers of myocardial tissue injury in diabetic hyperlipidaemic rats
Published in Archives of Physiology and Biochemistry, 2022
Mohamed M. Elseweidy, Sousou I. Ali, Noura I. Shershir, Abd Elmonem A. Ali, Sally K. Hammad
Haematoxylin and eosin staining of the myocardium of the normal group demonstrated normal characteristic features of myocardial muscle fibres and normal vasculature (Figure A(1)). The myocardium from diabetic hyperlipidaemic group demonstrated intense vacuolation (microsteatosis) and necrosis of cardiac myocytes. The later was represented by single or numerous empty clear vacuoles of variable sizes and sharp borders in the sarcoplasm with pyknotic dislocated nuclei besides oedema (Figure A(2)) and (Table 3). Occasionally complete replacement of the sarcoplasm with large vacuoles was encountered in addition to clusters of fat cells interposed between myocardial fibres. Congestion of blood vessels and hyalinisation of the blood vessel wall besides mild intimal destruction and subintimal foam cells (plaques) could be seen.
Histological and immunohistochemical study of the effect of ozone versus erythropoietin on induced skeletal muscle ischemia-reperfusion injury in adult male rats
Published in Ultrastructural Pathology, 2022
Magdy F. Gawish, Sally A. Selim, Alyaa A. Abd El-Star, Samah M. Ahmed
Ultrathin sections of skeletal muscle in the control showed normal architecture of muscle fibers with narrow inter-myofibrillar spaces. The sarcomere was in alignment with clear Z-line in the center of the I bands. Sarcoplasm contains numerous mitochondria located in the inter-myofibrillar space (Figure 7a). IR group showed injury of the muscular tissue in the form of fragmented fibers, irregular myofibrillar arrangement, cytoplasmic lysis with widened inter-myofibrillar spaces, and interrupted Z-lines (Figure 7b). Sarcoplasm contained variable-sized cytoplasmic vacuoles (Figure 7c) and swollen electron dense mitochondria with loss of their cristae (Figure 7d). Post-reperfusion ozone-treated group showed normal arrangement of the muscle fibers and normal pattern mitochondria except for wide inter-myofibrillar spaces (Figure 7e). Post-reperfusion EPO-treated group revealed regularly arranged myofibrils with narrow inter-myofibrillar spaces and normal mitochondrial pattern (Figure 7f). Recovering post-reperfusion without treatment group demonstrated myofibrils with some swollen electron dense mitochondria and variable-sized cytoplasmic vacuoles (Figure 7g). Other sections showed parts of myofibrils were invaded by fibroblasts and replaced by collagen fibers (Figure 7h).