1. End Show Slide 1 of 40 Copyright Pearson Prentice Hall 36–1 The Skeletal System

2. End Show 36–1 The Skeletal System Slide 2 of 40 Copyright Pearson Prentice Hall The Skeleton All organisms need structural support. Unicellular organisms have a cytoskeleton. Multicellular animals have either an exoskeleton (arthropods) or an endoskeleton (vertebrates).

3. End Show 36–1 The Skeletal System Slide 3 of 40 Copyright Pearson Prentice Hall The Skeleton The human skeleton is composed of bone. Bones and other connective tissues, such as cartilage and ligaments, form the skeletal system.

4. End Show 36–1 The Skeletal System Slide 4 of 40 Copyright Pearson Prentice Hall The Skeleton What are the functions of the skeletal system?

5. End Show 36–1 The Skeletal System Slide 5 of 40 Copyright Pearson Prentice Hall The Skeleton The skeleton: supports the body. protects internal organs. provides for movement. stores mineral reserves. provides a site for blood cell formation.

6. End Show 36–1 The Skeletal System Slide 6 of 40 Copyright Pearson Prentice Hall The Skeleton Axial Skeleton Skull Sternum Ribs Vertebral column The axial skeleton (blue) supports the central axis of the body.

7. End Show 36–1 The Skeletal System Slide 7 of 40 Copyright Pearson Prentice Hall The Skeleton Clavicle Scapula Humerus Radius Pelvis Ulna Carpals Metacarpals Phalanges Femur Patella Fibula Tibia Tarsals Metatarsals Phalanges Appendicular Skeleton The bones of the arms and legs, along with the bones of the pelvis and shoulder area form the appendicular skeleton (grey).

8. End Show 36–1 The Skeletal System Slide 8 of 40 Copyright Pearson Prentice Hall Structure of Bones What is the structure of a typical bone?

9. End Show 36–1 The Skeletal System Slide 9 of 40 Copyright Pearson Prentice Hall Structure of Bones Bones are a solid network of living cells and protein fibers that are surrounded by deposits of calcium salts.

10. End Show 36–1 The Skeletal System Slide 10 of 40 Copyright Pearson Prentice Hall Structure of Bones Bone marrow Periosteum Spongy bone Compact bone Haversian canal Compact bone Spongy bone Periosteum Osteocyte Artery Vein

11. End Show 36–1 The Skeletal System Slide 11 of 40 Copyright Pearson Prentice Hall 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.

12. End Show 36–1 The Skeletal System Slide 12 of 40 Copyright Pearson Prentice Hall 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.

13. End Show 36–1 The Skeletal System Slide 13 of 40 Copyright Pearson Prentice Hall Structure of Bones Spongy bone is found inside the outer layer of compact bone. Spongy bone is also found in the ends of long bones and in the middle of short, flat bones. Spongy bone adds strength without adding mass.

14. End Show 36–1 The Skeletal System Slide 14 of 40 Copyright Pearson Prentice Hall 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.

15. End Show 36–1 The Skeletal System Slide 15 of 40 Copyright Pearson Prentice Hall Structure of Bones Bone marrow is a soft tissue inside the cavities within bones. There are 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.

16. End Show 36–1 The Skeletal System Slide 16 of 40 Copyright Pearson Prentice Hall 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.

17. End Show 36–1 The Skeletal System Slide 17 of 40 Copyright Pearson Prentice Hall 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.

18. End Show 36–1 The Skeletal System Slide 18 of 40 Copyright Pearson Prentice Hall 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.

19. End Show 36–1 The Skeletal System Slide 19 of 40 Copyright Pearson Prentice Hall 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.

20. End Show 36–1 The Skeletal System Slide 20 of 40 Copyright Pearson Prentice Hall 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.

21. End Show 36–1 The Skeletal System Slide 21 of 40 Copyright Pearson Prentice Hall Structure of Joints Knee Joint Muscle Tendon Femur Patella Bursa Ligament Synovial fluid Cartilage Fat Fibula Tibia

22. End Show 36–1 The Skeletal System Slide 22 of 40 Copyright Pearson Prentice Hall 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. Synovial fluid enables the bones to slide past each other more smoothly.

23. End Show 36–1 The Skeletal System Slide 23 of 40 Copyright Pearson Prentice Hall 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.

24. End Show 36–1 The Skeletal System Slide 24 of 40 Copyright Pearson Prentice Hall 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.