EXSS1029 Lecture Notes - Lecture 9: Myofibril, Chronic Obstructive Pulmonary Disease

• School: University of Sydney
• Department: Exercise and Sport Science
• Course: EXSS1029
• Professor: Dr Tom Gwinn

Document Summary

Decrease in volume of the muscle (total tissue mass) Due to detraining, temporary disabling (restriction in movement) Rapid decrease in the overall volume of the muscle. > with the reintroduction of weightbearing = rapid increase in muscle volume. Caused by reduction in fibre cross sectional area. Decrease in cross sectional area of the remaining myofibrils. Disassembly of myofibrils thick/thin filaments released from sarcomeres and broken down into the individual actin/myosin proteins. * actin/myosin disassembled and broken down into their individual amino acids. Rate of protein synthesis is below the rate of protein breakdown. Removal of sarcomeres = disorganization of the remaining sarcomeres (thinner, disorganization of myofibrils and z lines) Results in decreased fibre cross sectional area. Due to removal of sections of myofibrils > there is disruption to the ability to produce force. Loss of csa = contractile proteins are decreased. Minimising atrophy: high resistance training during bed rest.