rav65819_ch47_943-962

rav65819_ch47_943-962 - ; 47 chapter The Musculoskeletal...

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chapter The Musculoskeletal System THE ABILITY TO MOVE is so much a part of our daily lives that we tend to take it for granted. It is made possible by the combination of a semirigid skeletal system, joints that act as hinges, and a muscular system that can pull on this skeleton. Animal locomotion can be thought of as muscular action that produces a change in body shape, which places a force on the outside environment. When a race horse runs down the track, its legs move forward and backward. As its feet contact the ground, the force they exert move its body forward at a considerable speed. In a similar way, when a bird takes off into flight, its wings exert force on the air; a swimming fish’s movements push against the water. In this chapter, we will examine the nature of the muscular and skeletal systems that allow animal movement.
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introduction concept outline Muscle bers contract as overlapping laments slide together f f Contraction depends on calcium ion release following a nerve impulse The two main types of muscle bers are slow-twitch and fast-twitch f Muscle metabolism changes with the demands made on it Physical training increases aerobic capacity and muscle strength 47.5 Modes of Animal Locomotion Aquatic animals demonstrate a number of locomotion adaptations Terrestrial locomotion must deal primarily with gravity Flying uses air for support 47.4 Muscle Contraction 47.1 Types of Skeletal Systems Hydrostatic skeletons use water pressure inside a body wall Exoskeletons consist of a rigid outer covering Endoskeletons are composed of hard, internal structures 47.2 A Closer Look at Bone Bones can be classi ed by two modes of development f Bone structure may include blood vessels and nerves Bone remodeling allows bone to respond to use or disuse 47.3 Joints and Skeletal Movement Moveable joints have different ranges of motion, depending on type Skeletal muscles pull on bones to produce movement at joints
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943 rav65819_ch47_943-962.indd 943 rav65819_ch47_943-962.indd 943 12/7/06 9:13:13 AM 12/7/06 9:13:13 AM 47.1 Types of Skeletal Systems Muscles have to pull against something to produce the changes that cause movement. This necessary form of supporting structure is called a skeletal system. Zoologists commonly recognize three types of skeletal systems in animals: hydrostatic skeletons, exoskeletons, and endoskeletons. Hydrostatic skeletons use water pressure inside a body wall Hydrostatic skeletons are found primarily in soft-bodied terrestrial invertebrates, such as earthworms and slugs, and soft-bodied aquatic invertebrates, such as jellyfish, squids, octopuses, and so on. Musculoskeletal action in earthworms
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rav65819_ch47_943-962 - ; 47 chapter The Musculoskeletal...

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