Anatomy and Physiology I Unit 7: The Skeletal System

1. Anatomy and Physiology I Unit 7: The Skeletal System Physiology of the Skeletal System

2. Skeletal System • Bones are made of several tissues • Primarily made of collagen and hydroxyapatite - Ca10(PO4)6(OH)2 • About 206 bones in the human body

3. Functions of Skeletal System • SUPPORT: Hard framework that supports and anchors the soft organs of the body. • PROTECTION: Surrounds organs such as the brain and spinal cord. • MOVEMENT: Allows for muscle attachment therefore the bones are used as levers. • STORAGE: Minerals and lipids are stored within bone material. • BLOOD CELL FORMATION: The bone marrow is responsible for blood cell production.

4. Parts of the Skeletal System • Axial skeleton • Skull and bones that support it • Includes vertebra and ribs • 80 bones • Appendicular skeleton • Limbs • 126 bones

5. Features of a Long Bone: Epiphysis: Ends of the bone. Diaphysis: The shaft of the bone which surrounds the medullary cavity. Articular Cartilage: Cushions the ends of the bones and allows for smooth movement. Epiphyseal Plate: Areas made of cartilage allowing for the growth of the bone.

6. Joints • Where bone meets bone • Ligament – holds bone to bone • Types of joints: • Immovable - skull • Ball-and-socket - shoulder • Hinge - knee • Pivot – forearm • Gliding - vertebrae

7. Joints • Cartilage covers ends of movable bones • Reduces friction • Lubricated by fluid from capillaries

8. Cartilage

9. Bone Structure • Periosteum – hard outer covering • Cells for growth and repair • Compact bone – hard strong layer • Bone cells, blood vessels, protein with Ca and P • Spongy bone – at ends of long bones • Has small open spaces to lighten weight • Marrow cavity – hollow in middle of long bones

10. Bone Marrow • Red marrow – produces blood cells and clotting factors • Found in humerus, femur, sternum, ribs, vertebrae, pelvis • Produces RBC 2 million per second • Yellow marrow – stores fat • Found in many bones

11. Bone Structure

12. Haversian System • Structure of compact bone • Rings of bone tissue with blood vessels and nerves in the center

13. Haversian System

14. Bone Development • Initial skeleton of cartilage in infants • Replaced with bone by osteoblasts • More than 300 bones at birth – fuse to 206 • Always growing and breaking down • Osteoblasts – form new bone cells • Osteoclasts – break bone cells down • Osteocytes – mature bone cells

15. Broken Bones • Fracture is a break of the bone • Simple or Complex fracture • Regrowth of bone: • Spongy bone forms in first few days • Blood vessels regrow and spongy bone hardens • Full healing takes 1-2 months

16. Homeostatic Imbalances Rickets • Disease of children due to a lack of vitamin D. • Calcium is not deposited in bones. • Bones become soft. • Bowing of the bones, and other deformities occur.

17. Homeostatic Imbalances Osteomalacia • “Rickets” of adults. • Due to a lack of vitamin D. • Calcium is not deposited in the bones. • Bones become brittle.

18. Homeostatic Imbalances Osteoporosis • Bone reabsorption is greater than bone deposition. • Due to any of the following: • Lack of estrogen in women. • Lack of exercise to stress the bones. • Inadequate intake of calcium and phosphorus. • Abnormalities of vitamin D metabolism. • Loss of muscle mass.

19. Age Related Dysfunctions Arthritis: Osteoarthritis- 90% of pop. By age 40 chronic inflammation of articular cartilage can be normal age-dependent change can also be pathology due to ? Age-related changes decrease blood supply trauma

20. Osteoarthritis

21. Osteoporosis Decline in Bone Density Bone Resorption > Bone Deposition Increase Risk for Fracture compression fractures of vertebrae hip fractures Role of calcium, vitamin D, estrogen, exercise Calcitonin vs. Parathyroid Hormone

22. Osteoporosis