| Terms – Be able to define each of the terms listed below. They are listed in the order in which they appear in the chapter:
- osseous tissue
- hydroxyapatite
- osteocyte
- lacunae
- lamellae
- canaliculi
- osteoblasts
- osteogenesis
- osteoprogenitor cell
- osteoclast
- compact bone
- spongy bone
- marrow cavity
- bone marrow
- yellow marrow
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- red marrow
- osteon
- central canal
- Haversian canal
- perforating canal
- trabeculae
- epiphysis
- diaphysis
- metaphysis
- periosteum
- endosteum
- ossification
- calcification
- intramembranous ossification
- endochondral ossification
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Notes
Test objectives are indicated by an asterisk (*).
Introduction
*Describe the functions of the skeletal system.
- Support
- Storage of Minerals and Lipids
- Blood Cell Production
- Protection
- Leverage
Structure of Bone
Histological Organization
* Describe the components of the matrix of the bone and the function of each of these components.
The Matrix of Bone
- Bone is a type of connective tissue (supporting connective tissue) and thus contains the components of cells and a matrix. (Click here to see the notes about connective tissue components.)
- Calcium phosphate + calcium hydroxide = hydroxyapatite - provides compressional strength (hydroxyapatite is the ground substance of bone tissue.)
- Collagen fibers – provide tensile strength, resistance to being stretched or torn apart.
The Cells of Bone
* List the names of the types of bone cells and describe their functions.
- Refer to Figure 5-1, page 113.
- Osteoprogenitor cells
- osteo = bone; pro = precursor; gen = to produce unspecialized cells that will differentiate into osteoblasts.
- Osteoblasts
- blast = germ, bud, precursor
- Found on inner or outer surface of bones
- Are the cells that form the bone; they secrete collagen and other organic components of bone tissue.
- Osteocytes – mature bone cells
- Osteoclasts
- clast = to break
- release enzymes that break down bone and release calcium and phosphate into the blood
- this process is continual
Compact and Spongy Bone
* Compare the structure and functions of compact and spongy bone.
- Refer to Figure 5-2, page 114.
- Compact bone forms the walls; surrounds the marrow cavity which contains yellow marrow, which contain adipocytes. The marrow cavity may contain red marrow.
Structural Differences Between Compact and Spongy Bone
Compact Bone
- Osteon (Haversian system) = functional unit of mature compact bone
Spongy Bone
- trabeculae - network of struts or thin, branching plates
- no osteons
Functional Differences Between and Compact and Spongy Bone
Compact bone
- compact bone where stress is found in just a few directions
- Parts of a long bone
- epiphyses (plural) (epiphysis, singular) = ends of long bone
- diaphysis = shaft of long bone
- metaphysis = region where the diaphysis meets the epiphysis
Spongy bone
The Periosteum and Endosteum
*Locate and compare the structure and function of periosteum and endosteum.
- See Figure 5-4, page 117.
- Periosteum = the membrane the covers bone; is essential for bone growth, repair, and nutrition. Is continuous with the ligaments and tendons.
- Endosteum = layer that lines the marrow cavity, covers the trabeculae, and lines the inner surface of the central canals of osteons. See Figure 5-4b, page 117 Go to perth.uwlax.edu/Biology/faculty/maher/skeleton/img009.jpg
Bone Development and Growth
Intramembranous Ossification
*Define intramembranous ossification.
- Intramembranous ossification is the process in which bone is formed directly in membranous tissue. It typically occurs for the formation of flat bones.
Endochondral Ossification
*Define endochondral ossification.
- Endochondral ossification is the process of replacing cartilage with bone.
- See Figure 5-7, page 120.
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