1. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint TextEdit Art Slides for Biology, Seventh Edition Neil Campbell and Jane Reece Ch. 44 Russell et al. Ch.9 Marieb Motor Mechanisms Bio-2 2009

2. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 49.25 Peristaltic locomotion in an earthworm (a)Body segments at the head and just in front of the rear are short and thick (longitudinal muscles contracted; circular muscles relaxed) and anchored to the ground by bristles. The other segments are thin and elongated (circular muscles contracted; longitudinal muscles relaxed.) (b)The head has moved forward because circular muscles in the head segments have contracted. Segments behind the head and at the rear are now thick and anchored, thus preventing the worm from slipping backward. (c) The head segments are thick again and anchored in their new positions. The rear segments have released their hold on the ground and have been pulled forward. Longitudinal muscle relaxed (extended) Circular muscle contracted Circular muscle relaxed Longitudinal muscle contracted Head Bristles

3. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 1 Ball-and-socket joints, where the humerus contacts the shoulder girdle and where the femur contacts the pelvic girdle, enable us to rotate our arms and legs and move them in several planes. 2 Hinge joints, such as between the humerus and the head of the ulna, restrict movement to a single plane. 3 Pivot joints allow us to rotate our forearm at the elbow and to move our head from side to side. Key Axial skeleton Appendicular skeleton Skull Shoulder girdle Clavicle Scapula Sternum Rib Humerus Vertebra Radius Ulna Pelvic girdle Carpals Phalanges Metacarpals Femur Patella Tibia Fibula Tarsals Metatarsals Phalanges 1 Examples of joints 2 3 Head of humerus Scapula Humerus Ulna Radius Figure 49.26 Bones and joints of the human skeleton

4. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 49.27 The interaction of muscles and skeletons in movement Human Grasshopper Biceps contracts Triceps relaxes Forearm flexes Biceps relaxes Triceps contracts Forearm extends Extensor muscle relaxes Flexor muscle contracts Tibia flexes Extensor muscle contracts Flexor muscle relaxes Tibia extends

5. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 49.28 The structure of skeletal muscle Muscle Bundle of muscle fibers Single muscle fiber (cell) Plasma membrane Myofibril Light band Dark band Z line Sarcomere TEM 0.5  m I bandA band I band M line Thick filaments (myosin) Thin filaments (actin) H zone Sarcomere Z line Nuclei

6. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 49.29 The sliding-filament model of muscle contraction (a) Relaxed muscle fiber. In a relaxed muscle fiber, the I bands and H zone are relatively wide. (b) Contracting muscle fiber. During contraction, the thick and thin filaments slide past each other, reducing the width of the I bands and H zone and shortening the sarcomere. (c) Fully contracted muscle fiber. In a fully contracted muscle fiber, the sarcomere is shorter still. The thin filaments overlap, eliminating the H zone. The I bands disappear as the ends of the thick filaments contact the Z lines. 0.5  m Z H A Sarcomere I

7. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 49.30 Myosin-actin interactions underlying muscle fiber contraction (layer 1) Thick filament Thin filaments Thin filament ATP Myosin head (low- energy configuration) Thick filament

8. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 49.30 Myosin-actin interactions underlying muscle fiber contraction (layer 2) Thick filament Thin filaments Thin filament ATP ADP P i Myosin head (low- energy configuration) Thick filament Actin Cross-bridge binding site

9. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 49.30 Myosin-actin interactions underlying muscle fiber contraction (layer 3) Thick filament Thin filaments Thin filament ATP ADP P i Cross-bridge Myosin head (low- energy configuration) Thick filament Actin Cross-bridge binding site

10. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 49.30 Myosin-actin interactions underlying muscle fiber contraction (layer 4) Thick filament Thin filaments Thin filament ATP ADP P i Cross-bridge Myosin head (low- energy configuration) + Thin filament moves toward center of sarcomere. Thick filament Actin Cross-bridge binding site Myosin head (low- energy configuration)

11. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 49.31 The role of regulatory proteins and calcium in muscle fiber contraction Actin Tropomyosin Ca 2+ -binding sites Troponin complex (a) Myosin-binding sites blocked Myosin- binding site Ca 2+ (b) Myosin-binding sites exposed

12. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 49.32 The roles of the sarcoplasmic reticulum and T tubules in muscle fiber contraction Motor neuron axon Mitochondrion Synaptic terminal T tubule Sarcoplasmic reticulum Myofibril Plasma membrane of muscle fiber Sarcomere Ca 2+ released from sarcoplasmic reticulum

13. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 49.33 Review of contraction in a skeletal muscle fiber ACh Synaptic terminal of motor neuron Synaptic cleft T TUBULE PLASMA MEMBRANE SR ADP CYTOSOL Action potential is propa- gated along plasma membrane and down T tubules. Action potential triggers Ca 2+ release from sarco- plasmic reticulum (SR). Acetylcholine (ACh) released by synaptic terminal diffuses across synaptic cleft and binds to receptor proteins on muscle fiber’s plasma membrane, triggering an action potential in muscle fiber. 1 2 3 Tropomyosin blockage of myosin- binding sites is restored; contraction ends, and muscle fiber relaxes. 7 Cytosolic Ca 2+ is removed by active transport into SR after action potential ends. 6 Myosin cross-bridges alternately attach to actin and detach, pulling actin filaments toward center of sarcomere; ATP powers sliding of filaments. 5 Calcium ions bind to troponin; troponin changes shape, removing blocking action of tropomyosin; myosin-binding sites exposed. 4 Ca 2  P2P2

14. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 49.34 Motor units in a vertebrate skeletal muscle Spinal cord Nerve Motor neuron cell body Motor unit 1 Motor unit 2 Motor neuron axon Muscle Tendon Synaptic terminals Muscle fibers

15. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 49.35 Summation of twitches Action potential Pair of action potentials Series of action potentials at high frequency Time Tension Single twitch Summation of two twitches Tetanus

16. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Table 49.1 Types of Skeletal Muscle Fibers

17. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 49.36 Energy-efficient locomotion on land

18. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 49.37 What are the energy costs of locomotion? Physiologists typically determine an animal’s rate of energy use during locomotion by measuring its oxygen consumption or carbon dioxide production while it swims in a water flume, runs on a treadmill, or flies in a wind tunnel. For example, the trained parakeet shown below is wearing a plastic face mask connected to a tube that collects the air the bird exhales as it flies. EXPERIMENT This graph compares the energy cost, in joules per kilogram of body mass per meter traveled, for animals specialized for running, flying, and swimming (1 J = 0.24 cal). Notice that both axes are plotted on logarithmic scales. RESULTS For animals of a given body mass, swimming is the most energy- efficient and running the least energy- efficient mode of locomotion. In any mode, a small animal expends more energy per kilogram of body mass than a large animal. CONCLUSION Flying Running Swimming 10 –3 10 3 10 6 1 10 –1 10 10 2 1 Body mass(g) Energy cost (J/Kg/m) Figure 49.37