1. Chapter 5 The Skeletal System

2. Structure of Bone
Figure 5.1

3. Skeletal System: Made of Connective Tissue
Bone: hard inorganic matrix of calcium salts
Compact: forms shaft and ends, contains marrow space
Spongy: trabeculae
Spaces between the trabeculae are filled with red bone marrow.
Does not rely on the osteon structure; the cells have direct access to the blood vessels
Cells:
Osteoblast; cells responsible for laying down new bone during bone remodeling
Osteocytes; mature bone cells contained in the lacunae
Osteoclasts; breaks down bone during bone remodeling
Types: long, flat, irregular
Osteons/haversian system: cellular arrangement
Periosteum: connective tissue that covers the outside of the bone

4. Cartilage and Ligaments
Cartilage: fibers of collagen or elastin in a ground substance of water
Function: support
3 Types:
Fibrocartilage; collagen fibers arranged in thick bundles
Withstands pressure and tension
Found between your vertebrae
Hyaline; thin collagen fibers
Forms the embryonic structures that later will become bone
Covers the ends of bones to reduce friction

5. Cartilage and Ligaments
Elastic cartilage; most elastin fibers
Highly flexible
Found in the outer ear and epiglottis
Ligaments
Function: attach bone to bone

6. Bone Development (cont.)
Blood vessels carry osteoblasts
Figure 5.2

7. Bone Development
Prenatal: cartilage model made by chondroblasts (cartilage forming cells)
Fetus: some conversion to bone  ossification
Childhood: primary and secondary ossification sites formed
Adolescence: cartilage growth plate elongates

8. Mature Bone Remodeling and Repair
Even after bones have stopped growing longer they are constantly changing
Changes in shape, size, strength
Dependent on diet, exercise, age

9. Mature Bone Remodeling and Repair
Bone cells regulated by hormones
Parathyroid hormone (PTH): removes calcium from bone
Calcitonin: adds calcium to bone
Negative feedback loop 9

10. Mature Bone Remodeling and Repair
Process of repair . . .
blood vessels in the area bleed producing a large blood clot (hematoma)
Fibroblasts (produce connective tissue) become chondroblasts and form a bond called a callus between the two ends of the bone
Bone breaks   
Osteoblasts arrive on the scene to convert the callus to bone
Osteoclasts remove dead fragments of bone and remove the hematoma 
How Bones Are Repaired 10

11. Functions of the Skeletal System
Protection: encases most internal organs
Support: allows body positions
Permits movement: muscle attachments for movement
Mineral reservoir: calcium and phosphorus

12. Axial Skeleton: Vertebral Column1 2
Cervical
vertebrae
(7) 3 4 5 6 7 1 2 3 4 5 6
Thoracic
vertebrae
(12)
Intervertebral
disks 7 8 9 10 11 12 1 2
Lumbar
vertebrae
(5) 3 4 5
Sacrum
(5 fused)
Coccyx
(4 fused)
Figure 5.7

13. Axial Skeleton: Vertebral Column (cont.)
Ribs
Twelve pairs
7 connected to the sternum via cartilage
8 – 10 connected to the 7 rib therefore, indirectly connected to the sternum
Bottom two pair floating; only connected to the vertebral column and not the sternum
Sternum: breastbone
Three bones fused together 13

14. Appendicular Skeleton
Pectoral girdle: shoulder
Clavicle and scapulas

15. Appendicular Skeleton
Pelvic girdles: hip
Coxal bones, sacrum, pubic symphysis 15

16. Joints (Articulations)
Classified by degree of movement
Fibrous joint: immovable
e.g., fontanels
Cartilagenous joint: slightly movable, cartilage connection
(e.g., backbone)
Synovial joint: freely movable
e.g. shoulder, knee

17. Synovial Joints
Knee Replacement
Knee Anatomy
Figure 5.12a

18. Synovial Joints (cont.)
Joint capsule:
Synovial membrane + hyaline cartilage
Synovial membrane secretes synovial fluid as a lubricant
Hyaline cartilage acts as a cushion

19. Diseases and Disorders of the Skeletal System
Sprains
stretched or torn ligaments
Bursitis and tendinitis
inflammations
Arthritis
inflammation of joints