Muscular System - Part 2 PDF - Abu Dhabi University Fall 2023

Muscular System - Part 2 Nermin Eissa, Ph.D. College of Health Sciences Abu Dhabi University Fall-2023 Learning Outcomes: Summarize how muscle cells produce ATP for muscle contraction. 2 ©2020 McGraw-Hi...

Muscular System - Part 2 Nermin Eissa, Ph.D. College of Health Sciences Abu Dhabi University Fall-2023 Learning Outcomes: Summarize how muscle cells produce ATP for muscle contraction. 2 ©2020 McGraw-Hill Education  Energy for Muscle Contraction Muscles have four different sources of energy: Two are stored in muscle (glycogen, triglycerides) and two are acquired from blood (glucose, fatty acids). Which of these are used depends on exercise intensity and duration. As time of exercise increases, use of muscle energy stores decreases and use of energy sources from the blood increases. 3 ©2020 McGraw-Hill Education  The Sources of Energy for Muscle Contraction Access the text alternative for these images 4 ©2020 McGraw-Hill Education  Sources of ATP for Muscle Contraction Muscle cells store limited amounts of ATP. Once it is used up, they have three ways to produce more ATP: The creatine phosphate (CP) pathway. Fermentation. Cellular respiration. Mitochondria uses oxygen, so is aerobic; neither the CP pathway nor fermentation requires oxygen (are anaerobic). 5 ©2020 McGraw-Hill Education  The Three Pathways by Which Muscle Cells Produce the ATP Energy Needed for Contraction Access the text alternative for these images 6 ©2020 McGraw-Hill Education  The Creatine Phosphate Pathway 1 The creatine phosphate pathway—the simplest and fastest way for muscle to make ATP 7 ©2020 McGraw-Hill Education  The Creatine Phosphate Pathway 2 Creatine phosphate is formed only when a muscle cell is resting, and only a limited amount is stored. Creatine phosphate-derived ATP powers the first few seconds of muscle contraction The CP pathway is used at the beginning of exercise. Creatine phosphate can only provide approximately 15 seconds worth of energy, at which point another energy source has to be used. 8 ©2020 McGraw-Hill Education  Fermentation 1 The anaerobic processes of glycolysis and fermentation produce two ATPs from the breakdown of glucose to lactate. Hormones signal cells to break down glycogen, making glucose available as an energy source. Fermentation, like the CP pathway, is fast-acting, but results in the buildup of lactate. Lactate produces short-term muscle aches and fatigue. 9 ©2020 McGraw-Hill Education  Fermentation 2 Oxygen debt—heavy breathing following strenuous exercise is required to complete the metabolism of lactate and restore cells to their original energy state. 10 ©2020 McGraw-Hill Education  Cellular Respiration Cellular respiration—the slowest of all three mechanisms used to produce ATP, but the most efficient. Occurs in the mitochondria. Myoglobin—a protein in muscle cells that delivers oxygen directly to the mitochondria. Can use glucose from stored glycogen, glucose in the blood, and fatty acids. 11 ©2020 McGraw-Hill Education  Check Your Progress Summarize how the CP pathway, fermentation, and cellular respiration produce ATP for muscle contraction. 12 ©2020 McGraw-Hill Education