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The Skeletal and Muscular Systems Structures of the Body • cells: the building blocks of life – make up your body – many types of cells • bone cells, muscle cells, blood cells, and nerve cells • tissue: cells of the same type working together – bone cells make bone tissue/muscle cells make up muscle tissue • organs: body parts that do special jobs – tissues of different kinds work together in organs • bone tissue and other tissue form organs of bones • muscle tissue and other tissue form organs of muscles • systems: groups of organs working together – bones (type of organ) work together to make the skeletal system – muscles (type of organ) work together to make the muscular system The Skeletal System • your body is made up of many bones – bones support your body and give it shape – help you move and protect the organs inside your body – bones meet at joints – some open and close like hinge of a door • your knee – other joints let a bone move in many directions • your shoulder The Muscular System • body has 3 types of muscles – skeletal muscles • • • • move head, arms, legs, fingers, toes can’t push, only pull work in pairs control skeletal muscles by thinking – cardiac muscles • muscle your heart is made of • muscle works without your thinking about it – smooth muscles • help organs inside your body do their job • muscle works without your thinking about it • all muscles move parts of your body • do this by getting longer and shorter A Closer Look at Muscles • striated muscles – skeletal muscle with light and dark stripes • stripes patterns made by working parts of muscle cell – fibers in skeletal muscle can be up to 30 cm (12in) long – some muscles have more than 2000 fibers packed together • smooth muscle – does not have stripes – found in walls of organs • stomach,intestines, blood vessels, bladder – work by squeezing and relaxing slowly and smoothly – fibers are shorter than skeletal muscles • cardiac muscle – – – – stripes but not as many as skeletal (striated) makes up walls of heart squeezes and relaxes without ever stopping never gets tired Summary • the body is made up of basic parts called cells – cells make up tissues – tissues make up organs – organs make up systems • skeletal and muscular systems work together to help the body move