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33 Cards in this Set

  • Front
  • Back
Bone: General Characteristics
Highly vascular since nutrients can't reach cell by diffusion
No nerve supply, (high nerve supply to periosteum and vasomotor nerves accompany blood vessels)
Metabolically active, undergoes continuous remodeling
Surface Covering: Periosteum - Structure
Dense Irregular CT surrounds outer surfaces of bones (except for articular surfaces)
Outer 'fibrous' layer - fibroblasts
Inner 'osteogenic' layer - osteoprogenitor cells
Sharpey's Fibers (collagen) extend from periosteum into bone
Surface Covering: Periosteum - Contents
Blood vessels, Lymph vessels, Nerves
Surface Covering: Periosteum - Function
Protects bone
Essential for growth and maintenance of bone
Surface Covering: Endosteum - Structure
Single layer of osteoprogenitor cells that lines all internal cavities of bone
Surface Covering: Endosteum - Function
Growth and Maintenance of bone
Surface Covering: Articular Cartilage
Layer of hyaline cartilage w/o perichondrium
Compact Bone - Appearance, Location
Appears as a solid mass
Location: peripherally
Cancellous (spongy, trabecular) Bone - Appearance, Location
Appears as a labyrinth of bony spicules and intervening spaces
Location: central
Long Bones: Diaphysis
Composition: compact bone w/inner surface lined w/small amount of cancellous bone
Surrounds Yellow Marrow Cavity
Long Bones: Epiphysis
Bulbous region at end of diaphysis
Composition: cancellous bone covered w/thin rim of compact bone
Surrounds Red Marrow
Long Bones: Epiphyseal Plate
Separates diaphysis and epiphysis
Region from which bone growth and length occurs
Composition: During growth - Hyaline Cartilage. After growth - Diaphysis/Epiphysis fuse -> epiphyseal line
Flat Bones: Plates (Tables)
Two plates, inner and outer
Composition: Compact bone
Flat Bone: Diploe
Located between inner and outer plates
Composition: Cancellous bone, line with Red Marrow
Red Marrow: Found in, Contains
Fetus: all bones
Adults: Cranial bones, vertebrae, ribs, irregular bones of hands and feet, epiphysis of long bones
Contains myeloid tissue (blood producing)
Yellow Marrow: Found in, Contains
Diaphysis of long bones
Contains mainly adipose tissue, retains potential to convert to red marrow if necessary (major injury)
Osteoblasts (Origin, inactive, active, location, secrete, become)
Originate: Mesenchymal cells (osteoprogenitor cells)
Inactive: flattened and ovoid
Active: Cuboidal
Located: surfaces of bone tissue (single layer, side by side)
Secrete: intercellular matrix (osteoid). Mineralize the osteoid.
Surround themselves with intercellular matrix and become osteocytes
Osteocytes (Origin, appearance, function)
Origin: Osteoblasts surrounded by minteralized intercellular matrix, lie 'real' cavities (lacunae)
Appear: Long cytoplasmic processes extend from cell body through tiny canals called 'canaliculi' to contact other cells via gap junctions
Appear similar to osteoblasts
Function: Transport materials btw blood and bone and maintain intercellular matrix
Osteoclasts (Origin, appearance, location, function)
Originate: monocytes in bone marrow
Appear: large, branched, motile cells w/5-50 nuclei
Located: surfaces of bone tissue in depressions called Howship's lacunae
Function: Resorm bone via proteolytic enzymes (respond to hormonal signals)
Extracellular Matrix: Organic Portion (Osteoid) - Fiber Component
90% of osteoid
Collagen type I fibers
Extracellular Matrix: Organic Portion (Osteoid) - Ground Substance
Proteoglycans (chondroitin and keratan sulfates)
Non-Sulfated Glycosaminoglycans (hyaluronic acid)
Glycoproteins (Bind Ca++)
Extracellular Matrix - Inorganic Portion
Primarily calcium and phosphorus
Form hydroxyapatite crystals that are depositied alongside collagen fibrils.
Appearance: Woven
Primary, Immature
First bone to appear in embryonic development and during repair processes
Random arrangement of collagen fibers
Has more osteocytes and less mineralized than lamellar bone.
Usually resorbed and replaced by lamellar bone (not much in adult)
Appearance: Lamellar
Secondary, Mature
Begins to form one month after birth
By age 4, most normal bone is lamellar
Highly organized layers of osteocytes and collagen fibers
Fewer osteocytes and more mineralized than woven bone
Architecture of Lamellar Bone: Compact (3)
Circumferential Lamellae
Haversian System (Osteon)
Interstitial Lamellae
Circumferential Lamellae
Layers of bone formed around inner and outer circumferences of a bone
Haversian System (Osteon)
Concentric Lamellae (4-20) arranged around a canal.
Canal - Contains a blood vessel and loose CT. Lined with endosteum. Connected to adjacent canals through perpendicularly running Volkmann's canals
Interstitial Lamellae
Incomplete Haversian systems that are left after resorption of the remainder of the osteon; located between complete Haversian Systems.
Architecture of Lamellar Bone: Cancellous Lamellar Bone
Thin trabeculae of lamellar bone with no Haversian Systems.
Physical Properties of Bone
Hard and Light
Resists Tensile, Compressive, and Shear Forces
Function of Bone (4)
Houses bone marrow where blood cells are formed
Reservoir for calcium, phosphate and other ions that are released or stored in response to endocrine hormones
Supports fleshy structures and protects vital organs
Forms system of levers that multiply the forces generated during skeletal muscle contraction and transform them into bodily movements.
Aging: Bone - Structural Changes
Btw 25 and 35 yrs, bone mass peaks. Afterwards the rate of resorption begins to exceed the rate of bone formation, resulting in decrease in bone mass.
Aging: Bone - Functional Changes
Enhanced bone fragility and consequent increase in fracture risk