Power Point Lecture Slides prepared by Meg Flemming
Power. Point® Lecture Slides prepared by Meg Flemming Austin Community College CHAPTER 7 The Muscular System © 2013 Pearson Education, Inc.
ATP and CP Reserves (7 -6) • At rest, muscle cells generate ATP, some of which will be held in reserve • Some is used to transfer high energy to creatine forming creatine phosphate (CP) © 2013 Pearson Education, Inc.
ATP and CP Reserves (7 -6) • During contraction each cross-bridge breaks down ATP into ADP and a phosphate group • CP is then used to recharge ATP • The enzyme creatine phosphokinase (CPK or CK) regulates this reaction • It lasts for about 15 seconds • ATP must then be generated in a different way © 2013 Pearson Education, Inc.
Aerobic Metabolism (7 -6) • Occurs in the mitochondria • Using ADP, oxygen, phosphate ions, and organic substrates from carbohydrates, lipids, or proteins • Substrates go through the citric acid cycle • A series of chemical reactions that result in energy to make ATP, water, and carbon dioxide • Oxygen supply decides ATP aerobic production © 2013 Pearson Education, Inc.
Glycolysis (7 -6) • Breaks glucose down to pyruvate in the cytoplasm of the cell • If pyruvate can go through the citric acid cycle with oxygen, it is very efficient • Forming about 34 ATP • With insufficient oxygen, pyruvate yields only 2 ATP • Pyruvate is converted to lactic acid • Potentially causing a p. H problem in cells © 2013 Pearson Education, Inc.
Figure 7 -9 Muscle Metabolism. Fatty acids G Blood vessels Glycogen Glucose Mitochondria Creatine Resting: Fatty acids are catabolized; the ATP produced is used to build energy reserves of ATP, CP, and glycogen. Fatty acids Glucose Glycogen 2 2 Pyruvate 34 34 To myofibrils to support muscle contraction Moderate activity: Glucose and fatty acids are catabolized; the ATP produced is used to power contraction. Lactate Glycogen Glucose 2 2 Pyruvate Creatine Lactate To myofibrils to support muscle contraction © 2013 Pearson Education, Inc. Peak activity: Most ATP is produced through glycolysis, with lactate and hydrogen ions as by-products. Mitochondrial activity (not shown) now provides only about one-third of the ATP consumed.
Figure 7 -9 a Muscle Metabolism. Fatty acids G Blood vessels Glucose Mitochondria Glycogen Creatine Resting: Fatty acids are catabolized; the ATP produced is used to build energy reserves of ATP, CP, and glycogen. © 2013 Pearson Education, Inc.
Figure 7 -9 b Muscle Metabolism. Fatty acids Glucose Glycogen 2 2 Pyruvate 34 34 To myofibrils to support muscle contraction Moderate activity: Glucose and fatty acids are catabolized; the ATP produced is used to power contraction. © 2013 Pearson Education, Inc.
Figure 7 -9 c Muscle Metabolism. Lactate Glucose Glycogen 2 2 Pyruvate Creatine Lactate To myofibrils to support muscle contraction Peak activity: Most ATP is produced through glycolysis, with lactate and hydrogen ions as by-products. Mitochondrial activity (not shown) now provides only about one-third of the ATP consumed. © 2013 Pearson Education, Inc.
Muscle Fatigue (7 -6) • Caused by depletion of energy reserves or a lowering of p. H • Muscle will no longer contract even if stimulated • Endurance athletes, using aerobic metabolism, can draw on stored glycogen and lipids • Sprinters, functioning anaerobically, deplete CP and ATP rapidly, and build up lactic acid PLAY ANIMATION Frog Fatigue © 2013 Pearson Education, Inc.
The Recovery Period (7 -6) • Requires "repaying" the oxygen debt by continuing to breathe faster • Even after the end of exercise, and recycling lactic acid • Heat production occurs during exercise • Raising the body temperature • Blood vessels in skin will dilate; sweat covers the skin and evaporates • Promoting heat loss © 2013 Pearson Education, Inc.
- Slides: 11