Chapter 6

Chapter Outline

1. Functions of the skeletal system
   1. Support
   2. Protection
   3. Movement
   4. Storage
   5. Blood cell production
2. Bone Anatomy
   1. Bone shape
      1. Long
      2. Short
      3. Flat
      4. Irregular
      5. Sesamoid
      6. Sutural
   2. Structure of a long bone
      1. Diaphysis and epiphysis
      2. Epiphyseal plate and line
      3. Medullary cavity and marrow
      4. Periosteum
   3. Structure of a falt bone
   4. Bone marrow
      1. Red
      2. Yellow
3. Bone (osseous) tissue
   1. Compact
   2. Spongy
4. Bone histology
   1. Bone matrix
      1. Hydroxyapatite (crystals made of calcium phosphate and calcium hydroxide)
   2. Bone cells
      1. Osteoprogenitor (stem cells)
      2. Osteoblasts
         1. Ossification or osteogenesis
      3. Osteocytes (mature bone cells)
         1. Lacunae
         2. Canaliculi
         3. Lamellae (calcified matrix)
      4. Osteoclasts (remove bone matrix)
   3. Origin of bone cells
      1. Woven bone
      2. Lamellar bone
         1. Spongy (cancellous) bone
            1. Trabeculae
            2. Oriented along stress lines
         2. Compact bone (made of osteon or haversian system)
            1. Haversian canals
            2. Concentric lamellae
            3. Osteons
            4. Interstitial lamellae
            5. Circumferential lamellae
            6. Perforating (volkmann's) canals
   4. Coverings of compact bone
      1. Periosteum
         1. Covers superficial layer of compact bone (except around joints)
         2. Separates the bone from surrounding tissues
         3. Provide a route for blood vessels and nerves
         4. Involved in bone growth and repair
      2. Endosteum
         1. Lines the marrow cavity
         2. Involved in bone growth, repair, remodeling
5. Bone development
   1. Ossification (bone formation)
      1. Intramembranous (from osteoprogenitors)
         1. Osteoprogenitor cells
         2. Centers of ossification
         3. Calcification (deposition of calcium salt)
         4. Remodeling
      2. Endocondral (from existing cartilage)
         1. Bone collar on cartilage model
         2. Chondrocyte hypertrophy
         3. Calcified cartilage
         4. Death of chondrocytes
         5. Primary ossification centers
         6. Secondary ossification centers
6. Bone growth
   1. Growth at epiphyseal plate (growth in length)
      1. Appositional growth only
      2. Resting cartilage
      3. Proliferation
      4. Hypertrophy
      5. Calcification
   2. Growth in diameter
      1. Appositional growth only
7. Bone remodelling
   1. Interstitial lamellae formation
   2. Response to mechanical stress (effect of exercise)
8. Factors that affect bone growth
   1. Nutrition
      1. Vitamin D
      2. Vitamin C
   2. Hormones
      1. Growth hormone
      2. Thyroid hormone
      3. Sex hormone
         1. Estrogen
         2. Testosterone
9. Bone repair
   1. Hematoma
   2. Internal callus
   3. External callus
   4. Cartilage ossification
   5. Bone remodeling
10. Calcium Homeostasis
    1. Parathyroid hormone (increases blood calcium levels)
    2. Calcitonin (decreases blood calcium levels)
11. Aging and the skeletal system
    1. Osteopenia (inadequate ossification)
    2. Osteoporosis

Review Questions

1. Where are the energy reserves in form of lipids stored in the bones of the skeleton?
2. What are the two types of osseous tissue and what is the difference between them?
3. What is the basic unit of mature compact bone?
4. Name the five primary functions of the skeletal system.
5. What is the functional difference between an osteoblast and an osteoclast?
6. What are the three primary functions of the periosteum?
7. Define diaphysis, epiphysis, epiphyseal plate, and epiphyseal line.
8. How does a bone increase in width? Describe the increase in length of bone at the epiphyseal plate and articular cartilage.
9. Name the two basic components of bone that are affected by nutritional status. How do vitamins D and C affect bone growth?
10. Name the hormones that regulate calcium levels in the body. Describe the effect of these hormones on the activity of bone cells.
11. Describe what happens during bone remodeling and bone repair.
12. Name the hormones that affect bone growth and development.

Readings

For any questions please call Dr. Maryam Bamshad at (718) 960-8646 or e-mail her at mbamshad@alpha.lehman.cuny.edu.