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36–1 The Skeletal System Photo Credit: © Getty Images Copyright Pearson Prentice Hall
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The Skeleton The human skeleton is composed of bone. Bones and other connective tissues, such as cartilage and ligaments, form the skeletal system. Copyright Pearson Prentice Hall
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The Skeleton What are the functions of the skeletal system? Copyright Pearson Prentice Hall
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The Skeleton The skeleton: supports the body. protects internal organs. provides for movement. stores mineral reserves. provides a site for blood cell formation. Copyright Pearson Prentice Hall
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The Skeleton Skull The axial skeleton (blue) supports the central axis of the body. Sternum Ribs Vertebral column The skeleton supports the body. The human skeleton is divided into two parts: the axial skeleton and the appendicular skeleton. Axial Skeleton Copyright Pearson Prentice Hall
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The Skeleton Clavicle The appendicular skeleton (grey) includes bones of the arms and legs, pelvis and shoulder area. Scapula Humerus Radius Pelvis Ulna Carpals Metacarpals Phalanges Femur The skeleton supports the body. The human skeleton is divided into two parts: the axial skeleton and the appendicular skeleton. Patella Fibula Tibia Tarsals Appendicular Skeleton Metatarsals Phalanges Copyright Pearson Prentice Hall
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Structure of Bones Structure of Bones What is the structure of a typical bone? Copyright Pearson Prentice Hall
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Structure of Bones Bones are a solid network of living cells and protein fibers that are surrounded by deposits of calcium salts. Copyright Pearson Prentice Hall
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Structure of Bones Haversian canal Spongy bone Compact bone Compact bone Periosteum Spongy bone Bone marrow Bones are a solid network of living cells and protein fibers that are supported by deposits of calcium salts. A typical long bone such as the femur contains spongy bone and compact bone. Within compact bone are Haversian canals, which contain blood vessels. Osteocyte Artery Vein Periosteum Copyright Pearson Prentice Hall
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Structure of Bones The bone is surrounded by a tough layer of connective tissue called the periosteum. Blood vessels in the periosteum carry oxygen and nutrients to the bone. Copyright Pearson Prentice Hall
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Structure of Bones Beneath the periosteum is a thick layer of compact bone. Running through compact bone is a network of tubes called Haversian canals that contain blood vessels and nerves. Copyright Pearson Prentice Hall
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Structure of Bones Spongy bone is: - found inside the outer layer of compact bone. - found in the ends of long bones and in the middle of short, flat bones. - adds strength without adding mass. Copyright Pearson Prentice Hall
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Structure of Bones Osteocytes, or mature bone cells, are embedded in the bone matrix. Other bone cells—osteoclasts and osteoblasts—line the Haversian canals and the surfaces of compact and spongy bone. Osteoclasts break down bone. Osteoblasts produce bone. Copyright Pearson Prentice Hall
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Structure of Bones Bone marrow is a soft tissue inside the cavities within bones. Two types of bone marrow: Yellow marrow is made up of fat cells. Red marrow produces red blood cells, some kinds of white blood cells, and platelets. Copyright Pearson Prentice Hall
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Development of Bones Development of Bones The skeleton of an embryo is composed of cartilage. Cartilage is a strong connective tissue that supports the body and is softer and more flexible than bone. Copyright Pearson Prentice Hall
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Development of Bones Cartilage is replaced by bone during the process of bone formation called ossification. Bone tissue forms as osteoblasts secrete mineral deposits. When the osteoblasts become surrounded by bone tissue, they mature into osteocytes. Copyright Pearson Prentice Hall
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Development of Bones Many long bones have growth plates at either end. Growth of cartilage at these plates causes bones to lengthen. Gradually, this cartilage is replaced by bone tissue. By early adulthood, cartilage in the growth plates is replaced by bone, the bones become ossified, and growth stops. Copyright Pearson Prentice Hall
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Types of Joints Types of Joints A place where one bone attaches to another bone is called a joint. Joints permit bones to move without damaging each other. Copyright Pearson Prentice Hall
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Types of Joints What are the three different kinds of joints? Copyright Pearson Prentice Hall
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Types of Joints Depending on its type of movement, a joint is classified as immovable, slightly movable, or freely movable. Copyright Pearson Prentice Hall
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Types of Joints Immovable Joints Immovable joints, called fixed joints, allow no movement. The bones are interlocked and held together by connective tissue, or they are fused together. Places where bones in the skull meet are examples of immovable joints. Copyright Pearson Prentice Hall
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Types of Joints Slightly Movable Joints Slightly movable joints permit a small amount of restricted movement. They are found in the joints between adjacent vertebrae (the spine). Copyright Pearson Prentice Hall
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Types of Joints Freely Movable Joints Freely movable joints permit movement in one or more directions. Four common freely movable joints are: ball-and-socket joints (shoulder) hinge joints (knee and elbow) pivot joints (head on shoulders) saddle joints (thumb) Copyright Pearson Prentice Hall
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Types of Joints Just Read (Do not write down) Ball-and-socket joints permit movement in many directions. The shoulder joint has a ball-and-socket joint. Copyright Pearson Prentice Hall
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Types of Joints Just Read (Do not write down) Hinge joints permit back-and-forth motion. The knee is a hinge joint., Copyright Pearson Prentice Hall
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Types of Joints Just Read (Do not write down) Pivot joints allow one bone to rotate around another. The elbow has a pivot joint. Copyright Pearson Prentice Hall
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Types of Joints Just Read (Do not write down) Saddle joints permit one bone to slide in two directions. The joint at the base of your thumb is a saddle joint. Copyright Pearson Prentice Hall
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Structure of Joints Structure of Joints In freely movable joints, cartilage covers the surfaces where two bones come together. Joints are also surrounded by a fibrous capsule that holds the bones together while still allowing them to move. Copyright Pearson Prentice Hall
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Structure of Joints Muscle Knee Joint Tendon Femur Patella Bursa Ligament Synovial fluid Cartilage The knee joint is protected by cartilage and bursae. The ligaments hold the bones composing the knee joint—femur, patella, tibia, and fibula—together. Fat Fibula Tibia Copyright Pearson Prentice Hall
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Structure of Joints Connective tissue called ligaments hold bones together in joints and are attached to membranes that surround bones. Synovial fluid forms a thin lubricating film over the surface of the joint and enables the bones to slide past each other more smoothly. Copyright Pearson Prentice Hall
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Structure of Joints In some freely movable joints small sacs of synovial fluid called bursae form. A bursa reduces the friction between bones of a joint and also acts as a shock absorber. Copyright Pearson Prentice Hall
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Skeletal System Disorders
Excessive strain on a joint may produce inflammation, in which excess fluid causes swelling, pain, heat, and redness. Inflammation of a bursa is called bursitis. Inflammation of the joint itself is called arthritis. Another skeletal system disorder is osteoporosis. Osteoporosis is caused by a loss of calcium in the bone. Copyright Pearson Prentice Hall
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36–1 Copyright Pearson Prentice Hall
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36–1 Red blood cells, some kinds of white blood cells, and platelets are produced by red marrow. cartilage. yellow marrow. osteocytes. Copyright Pearson Prentice Hall
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36–1 Mature bone cells are called periosteum. osteocytes. bone marrow. Haversian canals. Copyright Pearson Prentice Hall
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36–1 In freely movable joints, what covers the surfaces where the two bones come together? ligaments cartilage bursae tendons Copyright Pearson Prentice Hall
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36–1 During ossification, cartilage is replaced by bone. ligament. marrow. tendon. Copyright Pearson Prentice Hall
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36–1 The shoulder joint is an example of a ball-and-socket joint. hinge joint. pivot joint. saddle joint. Copyright Pearson Prentice Hall
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