And muscle physiology

Athletes associate performance with diet. Meat became a staple of ancient Greek and Roman athletes as they attempted to achieve the strength and endurance of carnivorous members of the animal kingdom. As knowledge of nutrition and muscle physiology increased, athletes became convinced that to increase muscle mass and strength required increased dietary protein. However, nutrition textbooks (1,2) and the Recommended Dietary Allowances (RDA s) established by the National Academy of Sciences (.3) state that there is little or no need for extra protein for exercise. 

Problems and efforts in biokinematics research are combined within a frame termed kinematics in order to describe and interpret the cormnon imderlying principles of motion to refer to moving parts (either body extremities or ridged mechanics attached to body extremities). In this respect, the terms and tools defined reflect the way of developing only the geometric displacement of motions specifically observed in medical science and clinical applications related to anatomy and (muscle) physiology. Kinematic variables considered mostly cover linear and angular displacements, velocities, and accelerations. 

Hardie DG, Sakamoto K (2006) AMPK a key sensor of fuel and energy status in skeletal muscle. Physiology (Bethesda) 21 48-60... 

The histopathological features of muscle samples from patients with myotonic dystrophy are not particularly distinctive. Early changes appear to be a selective atrophy of type 1 fibers, and hypertrophy of type 2 fibers, but the biochemical and/or physiological basis of these possibly related phenomena is not known. The incidence of degenerating fibers increases with age, although the presence of internally nucleated muscle fibers in early stages of the disease suggests that the muscle retains... 

Patterson, S., Klenerman, L., Biswas, M. and Rhodes, A.M. (1981). The effect of pneumatic tourniquets on skeletal muscle physiology. Acta Orthop. Scand. 52, 171-175. 

Both the G- and V-agents have the same physiological action on humans. They are potent inhibitors of the enzyme acetylcholinesterase (AChE), which is required for the function of many nerves and muscles in nearly every multicellular animal. Normally, AChE prevents the accumulation of acetylcholine after its release in the nervous system. Acetylcholine plays a vital role in stimulating voluntary muscles and nerve endings of the autonomic nervous system and many structures within the CNS. Thus, nerve agents that are cholinesterase inhibitors permit acetylcholine to accumulate at those sites, mimicking the effects of a massive release of acetylcholine. The major effects will be on skeletal muscles, parasympathetic end organs, and the CNS. 

Vallance, B.A., Blennerhassett, P.A., Deng, Y., Matthaei, K.I., Young, I.G. and Collins, S.M. (1999a) IL-5 contributes to worm expulsion and muscle hypercontractility in a primary T. spiralis infection. AmericanJournal of Physiology 211, G400-408. 

Parekh AB, Penner R 1997 Store depletion and calcium influx. Physiol Rev 77 901-930 Potocnik SJ, Hill MA 2001 Pharmacological evidence for capacitative Ca2+ entry in cannulated and pressurized skeletal muscle arterioles. Br J Pharmacol 134 247-256 Pozzan T, Rizzuto R, Volpe P, Meldolesi J 1994 Molecular and cellular physiology of intracellular calcium stores. Physiol Rev 74 595—636 Putney JW Jr, Broad LM, Braun FJ, Lievremont JP, Bird GS 2001 Mechanisms of capacitative calcium entry. J Cell Sci 114 2223—2229... 

To date, all smooth muscle types examined display characteristic Ca2+ release events known as Ca2+ sparks (Fig. 1 see Jaggar et al 2000 for review). Ca2+ sparks are localized Ca2+ release events through RyRs in the SR located very close (10—20nm) to the surface membrane. Ca2+ sparks can activate Ca2+ -dependent ion channels in the cell surface, and the physiological response of the particular cell type will reflect the type of ion channels involved (Fig. 1). 

This review aims at giving an overview of the NMR applications in meat science. This may be an idealistic scope, as meat science is not a strictly delimited area. In studies of the conversion of muscle to meat, initialised early post mortem, the limits to in vivo muscle physiology are vague, and therefore the differentiation of which studies belong to which discipline is subjective, and consequently studies have been included where we found it natural. Overall, the review attempts to demonstrate and discuss the different NMR methodologies (relaxometry, imaging, spectroscopy) and their potential applications within meat science based on the existing literature. In the end, conclusions will be drawn, and future perspectives are considered. 

This results in the extrusion of three positive charges for every two that enter the cell, resulting in a transmembrane potential of 50-70 mV, and has enormous physiological significance. More than one-third of the ATP utilized by resting mammalian cells is used to maintain the intracellular Na+-K+ gradient (in nerve cells this can rise up to 70%), which controls cell volume, allows neurons and muscle cells to be electrically excitable, and also drives the active transport of sugars and amino acids (see later). 

Where accumulation of citrate does occur, this may well react with calcium ions and cause consequent physiological disturbance in nerve and muscle. In this connexion it is interesting to note that fluoroacetate is relatively non-phytotoxic (for its use as systemic insecticide, see p. 182). 

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