Chapter 47: Effectors: Making Animals Move CHAPTER 47 Effectors: Making Animals Move

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

Chapter 47: Effectors: Making Animals Move Effectors Effectors enable animals to respond to information from their internal and external environments.Effectors enable animals to respond to information from their internal and external environments. Most effector mechanisms generate mechanical forces and cause movement.Most effector mechanisms generate mechanical forces and cause movement.3

Chapter 47: Effectors: Making Animals Move Cilia, Flagella, and Cell Movement Cell movement is generated by two structures, microtubules and microfilaments.Cell movement is generated by two structures, microtubules and microfilaments. Both consist of long protein molecules that can change length or shape.Both consist of long protein molecules that can change length or shape.4

Chapter 47: Effectors: Making Animals Move Cilia, Flagella, and Cell Movement The movements of cilia and flagella depend on microtubules.The movements of cilia and flagella depend on microtubules. Review Figures 47.1, 47.3,

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Chapter 47: Effectors: Making Animals Move Cilia, Flagella, and Cell Movement Microfilaments allow animal cells to change their shape and move.Microfilaments allow animal cells to change their shape and move.9

Chapter 47: Effectors: Making Animals Move Muscle Contraction The three types of vertebrate muscle are smooth, cardiac, and skeletal.The three types of vertebrate muscle are smooth, cardiac, and skeletal.10

Chapter 47: Effectors: Making Animals Move Muscle Contraction Smooth muscle provides contractile force for internal organs.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.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.Autonomic neurotransmitters alter the membrane potential of smooth muscle cells. Review Figure

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Chapter 47: Effectors: Making Animals Move Muscle Contraction The walls of the heart consist of sheets of branching cardiac muscle cells.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.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 heartbeatSome are pacemaker cells that generate heartbeat14

Chapter 47: Effectors: Making Animals Move Muscle Contraction Skeletal, or striated, muscle consists of muscle fiber bundles.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.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.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.During contraction, filaments slide past each other in a telescoping fashion. Review Figure

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Chapter 47: Effectors: Making Animals Move Muscle Contraction The molecular mechanism of muscle contraction involves binding of the globular heads of myosin molecules to actin.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.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.Release of the myosin heads from actin and return to original conformation requires ATP. Review Figure

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Chapter 47: Effectors: Making Animals Move Muscle Contraction The plasma membrane of the muscle fiber is continuous with a system of T tubules that extends deep into the sarcoplasm.The plasma membrane of the muscle fiber is continuous with a system of T tubules that extends deep into the sarcoplasm. Review Figure

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Chapter 47: Effectors: Making Animals Move Muscle Contraction When an action potential spreads across the plasma membrane and through the T tubules, it causes Ca 2+ ions to be released from the sarcoplasmic reticulum.When an action potential spreads across the plasma membrane and through the T tubules, it causes Ca 2+ ions to be released from the sarcoplasmic reticulum. Ca 2+ ions bind to troponin and change its conformation, pulling the tropomyosin strands away from the myosin binding sites on the actin filament.Ca 2+ 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 Ca 2+ is returned to the sarcoplasmic reticulum.Cycles of actin–myosin binding and release occur, and the muscle fiber contracts until Ca 2+ is returned to the sarcoplasmic reticulum. Review Figure

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Chapter 47: Effectors: Making Animals Move Muscle Contraction In striated muscle, a single action potential causes a minimum unit of contraction, a twitch.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.Twitches occurring in rapid succession can be summed, increasing the strength of contraction. Review Figure

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Chapter 47: Effectors: Making Animals Move Muscle Contraction Slow-twitch muscle fibers are adapted for extended, aerobic work; fast-twitch fibers for generating maximum forces for short periods.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.The ratio of slow- to fast-twitch fibers in an individual’s muscle is genetically determined. Review Figure

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Chapter 47: Effectors: Making Animals Move Skeletal Systems Provide Support for Muscles Skeletal systems provide rigid supports against which muscles can pull.Skeletal systems provide rigid supports against which muscles can pull.28

Chapter 47: Effectors: Making Animals Move Skeletal Systems Provide Support for Muscles Hydrostatic skeletons are fluid-filled cavities that can be squeezed by muscles.Hydrostatic skeletons are fluid-filled cavities that can be squeezed by muscles. Review Figure

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Chapter 47: Effectors: Making Animals Move Skeletal Systems Provide Support for Muscles Exoskeletons are hardened outer surfaces to which internal muscles are attached. Exoskeletons are hardened outer surfaces to which internal muscles are attached. Review Figure

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Chapter 47: Effectors: Making Animals Move Skeletal Systems Provide Support for Muscles Endoskeletons are internal, articulated systemsEndoskeletons are internal, articulated systems They are composed of rigid rod, plate, and tubelike supportsThey are composed of rigid rod, plate, and tubelike supports These consisting of bone and cartilage to which muscles are attached.These consisting of bone and cartilage to which muscles are attached. Review Figure

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Chapter 47: Effectors: Making Animals Move Skeletal Systems Provide Support for Muscles Bone is continually being remodeled by osteoblasts, which lay down new bone, and osteoclasts, which erode bone.Bone is continually being remodeled by osteoblasts, which lay down new bone, and osteoclasts, which erode bone. Review Figure

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Chapter 47: Effectors: Making Animals Move Skeletal Systems Provide Support for Muscles Bones develop from connective tissue membranes or from cartilage through ossification.Bones develop from connective tissue membranes or from cartilage through ossification. Cartilage bone can grow until centers of ossification meet.Cartilage bone can grow until centers of ossification meet. Review Figure

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Chapter 47: Effectors: Making Animals Move Skeletal Systems Provide Support for Muscles Bone can be solid and hard, or it can contain numerous internal spaces.Bone can be solid and hard, or it can contain numerous internal spaces.40

Chapter 47: Effectors: Making Animals Move Skeletal Systems Provide Support for Muscles Tendons connect muscles to bones.Tendons connect muscles to bones. Ligaments connect bones to each other and help direct forces generated by muscles by holding tendons in place.Ligaments connect bones to each other and help direct forces generated by muscles by holding tendons in place. Review Figure

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Chapter 47: Effectors: Making Animals Move Skeletal Systems Provide Support for Muscles Muscles and bones work together around joints as systems of levers.Muscles and bones work together around joints as systems of levers. Review Figures 47.20,

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Chapter 47: Effectors: Making Animals Move Other Effectors Effector organs other than musclesEffector organs other than muscles  nematocysts  chromatophores  glands  electric pulses Review Figure Review Figure