MBBS Muscle Tissue — practice questions

1. Because stored ATP in muscle lasts only a few seconds, muscle relies on a sequence of regeneration mechanisms. 2. Creatine phosphate transfers its phosphate to ADP very quickly via creatine kinase, powering the first few seconds of contraction. 3. However, creatine phosphate stores can only sustain about 15 seconds of activity. 4. Anaerobic glycolysis and aerobic respiration are the slower sources that take over afterward, and stored ATP alone lasts only a few seconds, all shorter or different from the 15-second creatine phosphate window. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 10 "Muscle Tissue", section 10.3, p. 419_

1. Aerobic respiration breaks down glucose or other nutrients with oxygen to produce carbon dioxide, water, and ATP in the mitochondria. 2. Because it is far more efficient per glucose molecule than glycolysis, it dominates ATP supply at rest. 3. Approximately 95 percent of the ATP required for resting or moderately active muscle comes from aerobic respiration. 4. 36 ATP per glucose is aerobic respiration's yield per molecule, a different figure from its percentage share of total ATP supply. 5. 50 percent understates how dominant aerobic respiration actually is at rest. 6. 15 percent understates it even further, closer to what anaerobic pathways alone might contribute. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 10 "Muscle Tissue", section 10.3, p. 420_