While the adaptive changes in diaphragm muscle are complex, ultimately EMP augments the energetic requirements of respiratory muscles which, concomitant with EMP-induced reductions in muscle mass, contributes to diaphragm weakness, increased fatigability and overall dysfunction.
Age-related changes in muscle are complex, with key features including myofiber atrophy, profound weakness that is partially independent of muscle mass loss, myofiber degeneration, accumulation of dysfunctional mitochondria, and increased oxidative stress.
The internal architecture of the jaw muscles is complex, with many exhibiting a complex pennate (feather-like) internal architecture.
Vertebrate skeletal muscles are complex organs composed by a variety of cell types besides the typical long, multinucleated cells called myofibers: fibroblasts in the connective layers, endothelial and smooth muscle cells in the vessel walls, nerves, and Schwann cells around the axons and blood cells flowing through the vessels.
Thus between multi-lineage progenitor cells such as mesoangioblasts, side-population cells and muscle-derived stem cells, pericytes, and classical satellite cells, the milieu of progenitor cells found in muscle tissue is complex and ever expanding.
Still, Ward notes that muscle fatigue is complex and that this one mechanism is only a part of the process.
The relative importance of different P2 receptor subtypes present in smooth muscle for contraction is complex and delineation of the contributions of specific subtypes complicated by the lack of highly selective agonists/antagonists. Available data suggest that G protein-coupled P2Y2, P2Y4, and P2Y6 receptors, and ionotropic P2X1 receptors contribute to nucleotide-mediated contraction.
The role of autophagy during the early phase of muscle wasting in ARDS is complex, given that either accelerated or impaired autophagy may be deleterious to muscle function.
Neuromuscular junction (NMJ) formation, occurring between motoneurons and skeletal muscle, is a complex multistep process involving a variety of signaling molecules and pathways.
The assembly of sarcomeres, the smallest contractile units in striated muscle, is a complex and highly coordinated process that relies on spatio-temporal organization of sarcomeric proteins, a process requiring spontaneous Ca2+ transients.
