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Bones and Skeletal Tissues


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What are the basic structures of a connective tissue?
-Consists of a jelly-like ground substance and collagen fibers.
-Primarily water.
-Surrounded by perichondrium, which acts as a girdle to resist outward expansion.
Where does connective tissues located?
-Found throughout adult body: ear & nose; articular cartilages & costal cartilage; larynx & cpiglottis; intervertebral discs & pubic symphysis.
Define Cartilage:
-is abundant in embryo
-Resilient tissue: springs back to original shape.
-Chondrocytes: connective tissue cells that form cartilage.
What are 3 types of cartilages in the adult body?
1. Hyaline cartilage (glass): most abundant cartilage that provides support through flexibility.
2. Elastic cartilage: contains many elastic fibers and able to tolerate repeated bending. (ex: ear and epiglottis)
3. Firbrocartilate: resists strong compression and strong tension. It acts as an intermediate between hyaline and elastic cartilage. (ex: meniscus)
Define 2 types of growth of cartilages:
1. Appositional growth: chondroblasts in surrounding perichondrium produce new cartilage.
2. Interstitial growth: chondrocytes within cartilage divide and secrete new matrix.
Define bones:
Organs that contain several types of tissues which are dominated by bone connective tissue. In additions, bones contain cartilage in articular cartilages; nervous tissue and blood tissue and epithelial tissue lining blood vessels.
What are the functions of bones?
1. Support: provides hard framework.
2. Protection of underlying organs.
3. Movement: skeletal muscles use bones as levers.
4. Mineral storage: reservoir for important minerals.
5. Blood-cell formation: bone contains red marrow.
Define 4 classifications of bones:
1. Long bones: longer than wide and a shaft plus ends.
2. Short bones: roughly cube-shaped.
3. Flat bones: thin and flattened, usually curved.
4. Irregular bones: various shapes, do not fit into other categories.
Define the structure of a long bones:
1. Diaphysis: "shaft" of a bone.
2. Epiphysis: ends of a bone; joint surface covered with articular cartilage.
3. Blood vessels: well vascularized.
4. Medullary cavity: hollow cavity that filled with marrow.
What is the structure of short, irregular and flat bones?
no diaphysis or marrow cavity.
What are the structures of long bones?
1. Periosteum: deep sublayer contact compact bone and contains osteoblasts and osteoclasts.
2. Sharpey's fibers: thick collagen bundles connecting periosteum to bone matrix.
3. Endosteum: covers the trabecullae of spongy bone.
4. Compact bone: dense outer layer of bone.
5. Spongy (cancellous) bone: internal honeycomb network of bone called trabeculae.
Define the gross anatomy of the bones:
1. Bone design and stress: Anatomy of bone reflects stresses; compression and tension greatest at external surfaces (compact bone)
2. Less tension internally on spongy bone: Trabecullae align with lines of compression and tension.
3. No stress in medullary cavity.
4. Bone remodels itself in response to external forces.
Define Osteon-Haversian System:
-Pillar like cyhnders.
-Collagen fibers in ring-like lamella run in opposing directions to resist forsum.
-central canal contains blood vessels and nerves.
Define osteocytes:
1. Mature bone cells residing in cavity called lacunae and that project into canniculi, thereby connecting the cells to capillaries and other osteocytes via gap junctions and allowing nutrients to diffuse from all to cell.
2. Maintain the bone matrix.
What are the composition of the bones?
1. 35% organic components composed of cells, fibers and organic substances. Collagen -abudant.
2. 65% inorganic mineral salts primarily calcium phosphate that function to resist compression
What does bone remodeling mean?
Bone deposit and removal that occurs at periosteal and endosteal surfaces.
2 types of bone remodeling:
1. Bone deposition: accomplished by osteoblasts.
2. Bone reabsorption: accomplished by osteoclasts.
Define osteoblasts:
1. Secretes the organic bone matrix called the osteoid.
2. Osteoid mineralizes with calcium salt crystals and surrounds the osteoblasts, thereby transforming it to an osteocyte.
Define Osteoclasts:
1. A giant cell with many nuclei.
2. Crawls along bone surfaces.
3. Breaks down bone tissue.
4. Secretes concentrated HCl to liberate Ca++ and PO4 ions.
5. Lysosomal enzymes are released to digest organic compounds.
Stages of healing fractures:
1. Hematoma formation.
2. Fibrocartilagenous callus formation.
3. Bony callus formation.
4. Bone remodeling
Common Types of Fractures:
1. Comminuted: fragment into 3 pieces or more.
2. Compression: Crushed.
3. Depressed: Pressed inward.
4. Emphyphyseal: separate epiphyis from diaphysis.
5. Green stick: 1 side is shaft splits while the other side blend.
6. Spiral: twist a bone.
5 types of bone disorders:
1. Osteoporosis: due to low bone mass. occurs mostly in women after menopause.
2. Osteomalacia: bones are inadequately mineralized usually occurs in adult.
3. Paget's disease: due to excessive rate of bone deposition.
4. Osteosarcoma: a form of bone cancer.

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