Home > 19 Muscle: Energy Metabolism and Contraction > METABOLISM AND MUSCLE CONTRACTION > Summary

Summary Body_ID: HC019033 Body_ID: P019035 Body_ID: F019007 Figure 19.7 Serum enzyme changes after myocardial infarction (MI). Various marker enzymes increase in plasma following MI. LDH, lactate dehydrogenase. These are still used for the diagnosis of MI, but the currently recommended test is the measurement of serum troponin concentration. Adapted from Pettigrew AR, Pacanis A. Diagnosis of myocardial infarction. In: Dominiczak MH, (ed.), Seminars in Clinical Biochemistry. University of Glasgow Computer Publishing Unit, Glasgow, 1997. Muscle is the major consumer of fuels and ATP in the body. Both glycolysis and lipid metabolism are essential for muscle activity. Reliance on these energy-producing pathways varies with muscle type and its prior contractile activity. The ATP produced in muscle drives the maintenance of ion gradients, restoration of intracellular calcium levels, and the contractile process. Fast, glycolytic muscle relies largely on glycogen and anaerobic glycolysis for short, high intensity bursts of muscle activity. Slow, oxidative muscle is an aerobic tissue; at rest, it uses fats as its primary source of energy. During the initial phases of exercise, it relies on glycogenolysis and glycolysis, but then gradually converts to fat metabolism for long-term energy production. Body_ID: P019034 Skeletal, cardiac, and smooth muscle have a common actomyosin contractile complex, but differ in innervation, contractile protein arrangement, calcium regulation of contraction, and propagation of depolarization from cell to cell. The sarcomere is the fundamental contraction unit of striated muscle and is defined by z-lines and thick and thin filament overlap. Contraction is described by a 'sliding-filament' model in which hydrolysis of ATP is catalyzed by an influx of Ca2+ into the sarcoplasm and is coupled to changes in the conformation of myosin. Relaxation of the high-energy conformation of myosin during interaction with actin produces a 'power stroke', resulting in increased overlap of the actin-myosin filaments and shortening of the sarcomere. Body_ID: P019036 page 270 page 271 Body_ID: P0271 ACTIVE LEARNING Body_ID: B019007 When chickens are frightened, they squawk a lot, may jump high and fly for short distances, but are unable to take flight and fly for great distances, either normally or to escape danger. In contrast, geese have the ability to fly for great distances, e.g. during semi-annual migrations. Compare the types of muscle fibers and energy resources in the breast of chicken and geese and explain how the differences in fiber type are compatible with the flying capacity of these birds. Discuss the impact of muscle glycogen phosphorylase deficiency (McArdle's disease) and carnitine or carnitine palmitoyl transferase I deficiency on muscle performance during short and long duration exercise. Review the merits of blood doping, carbohydrate loading and creatine supplementation to enhance performance during marathon events. Body_ID: PB19010 Further reading Body_ID: None Costelli P, Baccino FM. Mechanisms of skeletal muscle depletion in wasting syndromes: role of ATP-ubiquitin-dependent proteolysis. Curr Opin Clin Nutr Meta Care 2003;6:407-412. Full article Body_ID: R019001 Greenlund LJ, Nair KS. Sarcopenia - consequences, mechanisms, and potential therapies. Mech Ageing Dev 2003;124:287-299. Full article Body_ID: R019002 Hawley JA. Adaptations of skeletal muscle to prolonged, intense endurance training. Clin Exp Pharmacol Physiol 2002;29:218-222. Full article Body_ID: R019003 Henriksen EJ, Saengsirisuwan V. Exercise training and antioxidants: relief from oxidative stress and insulin resistance. Exerc Sport Sci Rev 2003;31:79-84. Full article Body_ID: R019004 Roberts CK, Vaziri ND, Liang KH, Barnard RJ. Reversibility of chronic experimental syndrome X by diet modification. Hypertension 2001;37:1323-1328. Body_ID: R019005 Roubenoff R. Catabolism of aging: is it an inflammatory process? Curr Opin Clin Nutr Metab Care 2003;6:295-299. Full article Body_ID: R019006 Tyska MJ, Warshaw DM.The myosin power stroke. Cell Motil Cytoskeleton 2002;51:1-15. Full article Body_ID: R019007 Relevant websites Body_ID: None Carnitine deficiency: http://www.emedicine.com/ped/topic321.htm Full article Body_ID: R019008 McArdle's Disease: www.muscular-dystrophy.org/information/KeyFacts/mcardles.html Full article Body_ID: R019009 Muscular Dystrophy: www.ninds.nih.gov/health_and_medical/disorders/md.htm Full article Body_ID: R019010 www.nlm.nih.gov/medlineplus/musculardystrophy.html Full article Body_ID: R019011 page 271 page 272 Body_ID: P0272 Body_ID: P0273 pages 270 - 272 Copyright © 2007 Elsevier Inc. All rights reserved. Read our Terms and Conditions of Use and our Privacy Policy. For problems or suggestions concerning this service, please contact: studentconsult.help@elsevier.com