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Copyright © 2010 Pearson Education, Inc. Motor Unit: The Nerve-Muscle Functional Unit Motor unit = a motor neuron and all (four to several hundred) muscle fibers it supplies
Copyright © 2010 Pearson Education, Inc. Figure 9.13a Spinal cord Motor neuron cell body Muscle Nerve Motor unit 1 Motor unit 2 Muscle fibers Motor neuron axon Axon terminals at neuromuscular junctions Axons of motor neurons extend from the spinal cord to the muscle. There each axon divides into a number of axon terminals that form neuromuscular junctions with muscle fibers scattered throughout the muscle.
Copyright © 2010 Pearson Education, Inc. Motor Units Small motor units in muscles that control fine movements (fingers, eyes) Large motor units in large weight-bearing muscles (thighs, hips)
Copyright © 2010 Pearson Education, Inc. Motor Unit Muscle fibers from a motor unit are spread throughout the muscle so that a single motor unit causes weak contraction of entire muscle If a muscle has more than one motor unit… Motor units in a muscle usually contract asynchronously; helps prevent fatigue
Copyright © 2010 Pearson Education, Inc. Muscle Tone Constant, slightly contracted state of all muscles Due to spinal reflexes that activate groups of motor units alternately in response to input from stretch receptors in muscles Does not produce movement, but keeps muscles firm, healthy, and ready to respond Helps maintain posture and stabilize joints
Copyright © 2010 Pearson Education, Inc. 2 Main Categories of Contraction Isotonic Muscle changes in length and moves the load Isometric The load is greater than the tension the muscle is able to develop The muscle neither shortens nor lengthens
Copyright © 2010 Pearson Education, Inc. Isotonic Contractions Isotonic contractions are either concentric or eccentric : Concentric contractions—the muscle shortens and does work Eccentric contractions—the muscle generates force as it lengthens
Copyright © 2010 Pearson Education, Inc. Isometric Isotonic
Copyright © 2010 Pearson Education, Inc. Figure 9.18a
Copyright © 2010 Pearson Education, Inc. Figure 9.18b
Copyright © 2010 Pearson Education, Inc. Check Point!!!!!! What is a motor unit? Betty White just signed up for a chin up competition to raise money for a local animal shelter. What type of muscle contractions are occurring in her biceps muscles immediately after she grabs the bar? As her body begins to move upward toward the bar? When her body begins to approach the mat?
Copyright © 2010 Pearson Education, Inc. Where does the body get the energy needed for contraction?
Copyright © 2010 Pearson Education, Inc. Muscle Metabolism: Energy for Contraction ATP is the only source used for muscle contraction Muscles store only 4–6 seconds worth of ATP at any given time. ATP must therefore be created as quickly as it is broken down for a contraction to continue
Copyright © 2010 Pearson Education, Inc. Muscle Metabolism: Energy for Contraction ATP is regenerated by: 1.Direct phosphorylation of ADP by creatine phosphate (CP) 2. Anaerobic pathway (glycolysis) 3. Aerobic respiration
Copyright © 2010 Pearson Education, Inc. Direct Phosphorylation Fastest form of ATP regeneration Creatine phosphate (CP) is stored in the muscles After stored ATP is used, CP combines with ADP to make more ATP Creatine phospate + ADP Creatine + ATP Can provide enough energy for 15 seconds of vigorous activity
Copyright © 2010 Pearson Education, Inc. Figure 9.19a Coupled reaction of creatine phosphate (CP) and ADP Energy source: CP (a) Direct phosphorylation Oxygen use: None Products: 1 ATP per CP, creatine Duration of energy provision: 15 seconds Creatine kinase ADPCP Creatine ATP
Copyright © 2010 Pearson Education, Inc. Anaerobic Pathway Glycolysis & Lactic Acid Formation Makes ATP by breaking down glucose Glucose breaks down into 2 pyruvic acid molecules, releasing energy to make ATP 2 ATP are produced per glucose molecule Pyruvic acid is then converted into lactic acid Produces less ATP than aerobic but it’s FAST! Can support strenuous activity for about a minute
Copyright © 2010 Pearson Education, Inc. Figure 9.19b Energy source: glucose Glycolysis and lactic acid formation (b) Anaerobic pathway Oxygen use: None Products: 2 ATP per glucose, lactic acid Duration of energy provision: 60 seconds, or slightly more Glucose (from glycogen breakdown or delivered from blood) Glycolysis in cytosol Pyruvic acid Released to blood net gain 2 Lactic acid O2O2 O2O2 ATP
Copyright © 2010 Pearson Education, Inc. Aerobic Pathway Produces 95% of ATP during rest and light to moderate exercise Occurs in the mitochondria and requires Oxygen Turns fuels (stored glycogen, bloodborne glucose, pyruvic acid from glycolysis, and free fatty acids) into ATP Produces 32 ATP per glucose, CO2, & H20
Copyright © 2010 Pearson Education, Inc. Figure 9.19c Energy source: glucose; pyruvic acid; free fatty acids from adipose tissue; amino acids from protein catabolism (c) Aerobic pathway Aerobic cellular respiration Oxygen use: Required Products: 32 ATP per glucose, CO 2, H 2 O Duration of energy provision: Hours Glucose (from glycogen breakdown or delivered from blood) 32 O2O2 O2O2 H2OH2O CO 2 Pyruvic acid Fatty acids Amino acids Aerobic respiration in mitochondria Aerobic respiration in mitochondria ATP net gain per glucose
Copyright © 2010 Pearson Education, Inc. Figure 9.20 Short-duration exercise Prolonged-duration exercise ATP stored in muscles is used first. ATP is formed from creatine Phosphate and ADP. Glycogen stored in muscles is broken down to glucose, which is oxidized to generate ATP. ATP is generated by breakdown of several nutrient energy fuels by aerobic pathway. This pathway uses oxygen released from myoglobin or delivered in the blood by hemoglobin. When it ends, the oxygen deficit is paid back.
Copyright © 2010 Pearson Education, Inc. Muscle Fatigue Physiological inability to contract even with a neural impulse Occurs when: ATP production fails to keep pace with ATP usage When ATP use exceeds its production Total lack of ATP occurs rarely, results in states of continuous contraction (contracture) Example: Writer’s Cramp
Copyright © 2010 Pearson Education, Inc. Oxygen Deficit Exercise uses oxygen stores in the muscle Oxygen demand rises so extra Oxygen must be taken in by the body to restore normal levels of Oxygen Vigorous exercise heavy breathing restores balance
Copyright © 2010 Pearson Education, Inc. Heat Production During Muscle Activity Only about 40% of the energy released in muscle activity is useful as work Remaining energy (60%) given off as heat Dangerous heat levels are prevented by radiation of heat from the skin and sweating Conversely, shivering will increase body temperature when cold
Copyright © 2010 Pearson Education, Inc. Critical Thinking!!! When Eric returned from jogging, he was breathing heavily, sweating profusely, and complained that his legs ached and felt weak. His wife poured him a sports drink and urged him to take it easy until he could “catch his breath.” On the basis of what you have learned about muscle energy metabolism, respond to the following questions: Why is Eric breathing heavily? What ATP-generating pathway have his working muscles been using that leads to such breathlessness? What metabolic pathway might account for his sore muscles and his feeling of muscle weakness?
PowerPoint ® Lecture Slides prepared by Janice Meeking, Mount Royal College C H A P T E R Copyright © 2010 Pearson Education, Inc. 9 Muscles and Muscle.
© 2013 Pearson Education, Inc. Motor Unit: Nerve-Muscle Functional Unit Each muscle served by at least one motor nerve –Motor nerve contains axons of up.
Muscle Metabolism. Goals: Describe three ways in which ATP is regenerated during muscle contraction Relate the oxygen deficit to causes of muscle fatigue.
Copyright © 2010 Pearson Education, Inc. Chapter 9 Muscles And Muscle Tissue Part B Shilla Chakrabarty, Ph.D.
Copyright © 2010 Pearson Education, Inc. THE MUSCULAR SYSTEM (PHYSIOLOGY) CHAPTER # 9(b)
Pages Muscle fiber contraction is “all or none” ◦ There is no “in-between” contraction Not all fibers may be stimulated at one time Different.
PowerPoint ® Lecture Slides prepared by Barbara Heard, Atlantic Cape Community College C H A P T E R © 2013 Pearson Education, Inc.© Annie Leibovitz/Contact.
© 2013 Pearson Education, Inc. Review Principles of Muscle Mechanics Same principles apply to contraction of single fiber and whole muscle Contraction.
* Set up for “Memory” * Create flashcards for: * Perimysium * Synergist * Aerobic * Leukocytes * Plasma * Eccentric contraction * Leukemia * Motor Unit.
PowerPoint ® Lecture Slide Presentation by Patty Bostwick-Taylor, Florence-Darlington Technical College Copyright © 2009 Pearson Education, Inc., publishing.
The Muscular System. Contraction of Skeletal Muscle Muscle fiber contraction is “all or none” Within a skeletal muscle, not all fibers may be stimulated.
The Sliding Filament Theory Slide 6.18 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6.8.
ELAINE N. MARIEB EIGHTH EDITION 6 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture Slide Presentation by.
Essentials of Human Anatomy & Physiology Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Seventh Edition Elaine N. Marieb Chapter.
PRINCIPLES OF HUMAN PHYSIOLOGY THIRD EDITION Cindy L. Stanfield | William J. Germann PowerPoint ® Lecture Slides prepared by W.H. Preston, College of the.
Muscle Tissue. Summary General General Types of muscle tissue Types of muscle tissue Functional characteristics Functional characteristics Functions Functions.
Muscle Contraction. Providing Energy for Muscle Contraction Muscles store very limited supplies of ATP - only 4 to 6 seconds, just enough to get you.
Quiz – Write question and answer 1.Name the 3 types of muscle tissue 2.Which type of muscle is voluntary? 3.Name 2 of the 4 functions of muscles 4.Name.
PowerPoint ® Lecture Slides prepared by Karen Dunbar Kareiva Ivy Tech Community College © Annie Leibovitz/Contact Press Images Chapter 9 Part B Muscles.
Chapter 6 The Muscular System. The Sliding Filament Theory.
Muscle & Energy Intro A single muscle fiber contains 15 billion thick filaments During active contraction, 2500 ATP molecules are used-PER SECOND!! muscles.
Muscles and Muscle Tissue Part B Prepared by Janice Meeking & W. Rose. Figures from Marieb & Hoehn 8 th ed. Portions copyright Pearson Education.
1 Energy Sources for Contraction Creatine phosphate – stores energy that quickly converts ADP to ATP 1) Creatine phosphate 2) Cellular respiration ATP.
Muscles and Muscle Tissue Part C1 Prepared by Janice Meeking, W. Rose, and Jarvis Smith. Figures from Marieb & Hoehn 8 th ed. Portions copyright Pearson.
Figure Figure The Arrangement of Motor Units in a Skeletal Muscle.
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ENERGY SOURCES FOR MUSCLE CONTRACTION. Objectives 1.Energy used 2.Energy produced 3.Oxygen debt 4.Muscle fiber types 5.Muscle fatigue.
Smooth - no striations, involuntary visceral organs Skeletal - striated, voluntary, tires easily, powerful Cardiac - striated, involuntary intercalated.
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Chapter 6 The Muscle Physiology. Nerve Stimulus to Muscles Synaptic cleft – gap between nerve and muscle - no contact - filled with interstitial fluid.
Aerobic & Anaerobic Metabolism in Muscles. Objectives Recognize the importance of ATP as energy source in skeletal muscle. Understand how skeletal muscles.
Muscle Metabolism Aerobic respiration: produces large amounts of ATP but requires O 2 to function, waste products: water, CO 2 Anaerobic fermentation:
Cellular Respiration. Learning Intention: To learn about cellular respiration Success Criteria: By the end of the lesson I should be able to Describe.
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Essentials of Human Anatomy & Physiology Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slides 6.1 – 6.17 Seventh Edition Elaine.
MUSCULAR SYSTEM NOTES. Byproduct is lactic acid Occurs when muscle cells have used all the oxygen available to them (muscles bulge during intense.
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