Contraction, muscular

The role of ATP in muscular contraction has parallels to the role of GTP in G-protein activation... 

Hibberd, M.G. Trentham, D.R. (1986). Relationships between chemical and mechanical events during muscular contraction. Ann. Rev. Biophys. Chem. 15, 119-136. 

Huxley, H.E. (1973). Muscular contraction and cell motility. Nature 243,445-449. 

The vital processes—eg, synthetic reactions, muscular contraction, nerve impulse conduction, and active transport—obtain energy by chemical linkage, or coupling, to oxidative reactions. In its simplest form, this type of coupling may be represented as shown in Figure 10—1. The conversion of metabolite A to metabolite B... 

Figure 12-14. The creatine phosphate shuttle of heart and skeletal muscle. The shuttle allows rapid transport of high-energy phosphate from the mitochondrial matrix into the cytosol. CKg, creatine kinase concerned with large requirements for ATP, eg, muscular contraction CIC, creatine kinase for maintaining equilibrium between creatine and creatine phosphate and ATP/ADP CKg, creatine kinase coupling glycolysis to creatine phosphate synthesis CK, , mitochondrial creatine kinase mediating creatine phosphate production from ATP formed in oxidative phosphorylation P, pore protein in outer mitochondrial membrane.

Skeletal muscle utilizes glucose as a fuel, forming both lactate and CO2. It stores glycogen as a fuel for its use in muscular contraction and synthesizes muscle protein from plasma amino acids. Muscle accounts for approximately 50% of body mass and consequently represents a considerable store of protein that can be drawn upon to supply amino acids for gluconeogenesis in starvation. 

Proteins play an important role in movement at both the organ (eg, skeletal muscle, heart, and gut) and cellular levels. In this chapter, the roles of specific proteins and certain other key molecules (eg, Ca ) in muscular contraction are described. A brief coverage of cyto-skeletal proteins is also presented. 

Inotropic Relating to or influencing the force of muscular contractions, usually referring to changes in the contractile state of the heart. 

For over three decades, laboratory research has shown caffeine to be effective at mobilizing calcium in skeletal muscle. In vitro experiments have amply demonstrated that caffeine lowers the excitability threshold and extends the length of muscular contractions via calcium release from the sarcoplasmic reticulum.1012 Caffeine also inhibits calcium reuptake by the sarcoplasmic reticulum, perpetuating calcium availability for muscle work.1318 Also, caffeine promotes increased twitch tension development in muscles.1718... 

Although research has been suggestive of caffeine modulated increases in muscular contractions leading to hand tremor, it is more likely that the hand tremor response is the result of caffeine s effects on the central nervous system.32 There is even evidence that moderate doses of caffeine may actually diminish muscle tone.32... 

The contents of the tract must also be continually moved along so that it can be acted upon by the sequential regions of the tract. Peristalsis is a muscular contraction that produces a ring of contraction that moves along the length of the tract. This wave-like contraction causes propulsion and forces the contents forward. Peristalsis is more important in the esophagus and stomach. 

From his early youth, under his father s influence, K. H. Meyer had retained a keen interest in biological problems, as was evident from his study of the phenomena of narcosis, which he pursued during his stay in industry. As a natural consequence, he extended his thoughts to biological problems, and evolved a quantitative theory of muscular contraction (in collaboration with Picken), based on analogies with the elasticity of rubber. With J. F. Sievers, the permeability of synthetic membranes was investigated, and a mathematical treatment of the phenomenon was advanced which was later applied to living membranes. 

CDC Case Definition Acute onset of hypertonia and/or painful muscular contractions (usually of the muscles of the jaw and neck) and generalized muscle spasms without other apparent medical cause. 

Phenotype determined by cortical region activated (e.g. if motor cortex representing left thumb is activated, then left thumb jerking results). Consciousness is preserved Impaired consciousness lasting seconds to minutes, often associated with automatisms such as lip smacking Simple or partial complex seizure evolves into a tonic-clonic seizure with loss of consciousness. There are sustained muscular contractions (tonic) followed by periods of relaxation (clonic) lasting 1-2 min... 

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