CHAPTER 47 Effectors: Making Animals Move

1. CHAPTER 47Effectors: Making Animals Move

2. Chapter 47: Effectors: Making Animals Move Effectors Cilia, Flagella, and Cell Movement Muscle Contraction Skeletal Systems Provide Support for Muscles Other Effectors

3. Effectors • Effectors enable animals to respond to information from their internal and external environments. • Most effector mechanisms generate mechanical forces and cause movement. 3

4. Cilia, Flagella, and Cell Movement • Cell movement is generated by two structures, microtubules and microfilaments. • Both consist of long protein molecules that can change length or shape. 4

5. Cilia, Flagella, and Cell Movement • The movements of cilia and flagella depend on microtubules. Review Figures 47.1, 47.3, 47.4 5

6. figure 47-01.jpg Figure 47.1 Figure 47.1

7. figure 47-03.jpg Figure 47.3 Figure 47.3

8. figure 47-04.jpg Figure 47.4 Figure 47.4

9. Cilia, Flagella, and Cell Movement • Microfilaments allow animal cells to change their shape and move. 9

10. Muscle Contraction • The three types of vertebrate muscle are smooth, cardiac, and skeletal. 10

11. Muscle Contraction • Smooth muscle provides contractile force for internal organs. • Smooth muscle cells are electrically coupled through gap junctions, so action potentials causing contraction spread rapidly throughout the tissue. • Autonomic neurotransmitters alter the membrane potential of smooth muscle cells. Review Figure 47.6 11

12. figure 47-06a.jpg Figure 47.6 – Part 1 Figure 47.6 – Part 1

13. figure 47-06b.jpg Figure 47.6 – Part 2 Figure 47.6 – Part 2

14. Muscle Contraction • The walls of the heart consist of sheets of branching cardiac muscle cells. • The cells are electrically coupled through gap junctions, so action potentials spread rapidly throughout sheets of cardiac muscle and cause coordinated contractions. • Some are pacemaker cells that generate heartbeat 14

15. Muscle Contraction • Skeletal, or striated, muscle consists of muscle fiber bundles. • Each muscle fiber is a huge cell containing multiple nuclei and numerous myofibrils, which are bundles of actin and myosin filaments. • The regular, overlapping arrangement of the filaments into sarcomeres gives the muscle a striated appearance. • During contraction, filaments slide past each other in a telescoping fashion. Review Figure 47.7 15

16. figure 47-07a.jpg Figure 47.7 – Part 1 Figure 47.7 – Part 1

17. figure 47-07b.jpg Figure 47.7 – Part 2 Figure 47.7 – Part 2

18. Muscle Contraction • The molecular mechanism of muscle contraction involves binding of the globular heads of myosin molecules to actin. • Upon binding, the myosin head changes conformation, causing the two filaments to move relative to each other. • Release of the myosin heads from actin and return to original conformation requires ATP. Review Figure 47.8 18

19. figure 47-08.jpg Figure 47.8 Figure 47.8

20. Muscle Contraction • The plasma membrane of the muscle fiber is continuous with a system of T tubules that extends deep into the sarcoplasm. Review Figure 47.9 20

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22. Muscle Contraction • When an action potential spreads across the plasma membrane and through the T tubules, it causes Ca2+ ions to be released from the sarcoplasmic reticulum. • Ca2+ ions bind to troponin and change its conformation, pulling the tropomyosin strands away from the myosin binding sites on the actin filament. • Cycles of actin–myosin binding and release occur, and the muscle fiber contracts until Ca2+ is returned to the sarcoplasmic reticulum. Review Figure 47.10 22

23. figure 47-10.jpg Figure 47.10 Figure 47.10

24. Muscle Contraction • In striated muscle, a single action potential causes a minimum unit of contraction, a twitch. • Twitches occurring in rapid succession can be summed, increasing the strength of contraction. Review Figure 47.11 24

25. figure 47-11.jpg Figure 47.11 Figure 47.11

26. Muscle Contraction • Slow-twitch muscle fibers are adapted for extended, aerobic work; fast-twitch fibers for generating maximum forces for short periods. • The ratio of slow- to fast-twitch fibers in an individual’s muscle is genetically determined. Review Figure 47.12 26

27. figure 47-12.jpg Figure 47.12 Figure 47.12

28. Skeletal Systems Provide Support for Muscles • Skeletal systems provide rigid supports against which muscles can pull. 28

29. Skeletal Systems Provide Support for Muscles • Hydrostatic skeletons are fluid-filled cavities that can be squeezed by muscles. Review Figure 47.13 29

30. figure 47-13a.jpg Figure 47.13 – Part 1 Figure 47.13 – Part 1

31. figure 47-13b.jpg Figure 47.13 – Part 2 Figure 47.13 – Part 2

32. Skeletal Systems Provide Support for Muscles • Exoskeletons are hardened outer surfaces to which internal muscles are attached. Review Figure 47.14 32

33. figure 47-14.jpg Figure 47.14 Figure 47.14

34. Skeletal Systems Provide Support for Muscles • Endoskeletons are internal, articulated systems • They are composed of rigid rod, plate, and tubelike supports • These consisting of bone and cartilage to which muscles are attached. Review Figure 47.15 34

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36. Skeletal Systems Provide Support for Muscles • Bone is continually being remodeled by osteoblasts, which lay down new bone, and osteoclasts, which erode bone. Review Figure 47.16 36

37. figure 47-16.jpg Figure 47.16 Figure 47.16

38. Skeletal Systems Provide Support for Muscles • Bones develop from connective tissue membranes or from cartilage through ossification. • Cartilage bone can grow until centers of ossification meet. Review Figure 47.17 38

39. figure 47-17.jpg Figure 47.17 Figure 47.17

40. Skeletal Systems Provide Support for Muscles • Bone can be solid and hard, or it can contain numerous internal spaces. 40

41. Skeletal Systems Provide Support for Muscles • Tendons connect muscles to bones. • Ligaments connect bones to each other and help direct forces generated by muscles by holding tendons in place. Review Figure 47.19 41

42. figure 47-19.jpg Figure 47.19 Figure 47.19

43. Skeletal Systems Provide Support for Muscles • Muscles and bones work together around joints as systems of levers. Review Figures 47.20, 47.21 43

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45. figure 47-21.jpg Figure 47.21 Figure 47.21

46. Other Effectors • Effector organs other than muscles • nematocysts • chromatophores • glands • electric pulses Review Figure 47.22 46