Chapter 6 Flashcards
Six main functions of skeletal system
Support
Protection
Assistance in movement
Mineral homeostasis (storage/release)
Blood cell production
Tryglyceride storage
Explain how bones control mineral homeostasis
Bone stores minerals, especially calcium and phosphorus and release on demand into blood
What Percentage of body mass is bone? What percentage of calcium is stored in bone
18
99
Explain blood cell production in bones
Red bone marrow produces RBC WBC and platelets: called hemopoises
Red bone marrow is made of what? Where is it found
Consists of blood cells Adipocytes fibroblasts macrophages in network of reticular fibers
Found in bones of fetus/ some adult (hip,ribs,sternum,vertebrae,skull, ends of humerus/femur)
Explain tryglyceride storage in bones
Yellow bone marrow consists of mainly adipose cells=potential energy reserve
Diaphysis
Bone shaft
Epiphyses
Proximal/distal end
Metaphyses
Between diaphyses/epiphyses
Contains epiphyseal plate=hyaline cartilage allowing diaphyses to grow
Epiphyseal line: at 14-24 replaces plate with bone
Articular cartilage
Thin layer hyaline cartilage covering epiphyseal at joint, no perichondrium/BV=limited repair
Periosteum/layers
Thought connective tissue sheath/blood supply surrounds bone not covered by articular cartilage
Outer fibrous layer: dense irregular connective tissue
Inner osteogenic layer: cells
Protects repairs nourish attachment point (ligaments/tendons)
Perforating fibers
Thick bundles of collagen attatching periosteum to bone
Medullary cavity (marrow cavity)
Hollow space in diaphyses containing YBM/BV, minimizes weight of bone
Endostuem
Thin membrane lines medullary cavity, has bone forming cells/connective tissue
Other name for bone
Osseous tissue
ECM of bone
15% water
30% collagen fibers
55% crystallized minerals salts
Hydroxyapatite
Calcium phosphate and calcium hydroxide
Calcification
Mineral salts crystallized=tissue hardens
Requires collagen fibers
What helps bone hardness/flexibility
Crystallized inorganic mineral salts=hardness
Collagen fibers=flexibility
Cells in bone tissue
Osteoprogenitor cells
Osteoblasts
Osteocytes
Osteoclasts
Osteoprogenitor cells
Unspecialized bone stem cells become osteoblasts
Found along Inner portion of periosteum, in endosteum, in canal in bone containing BV
Osteoblasts
Bone building cells, synthesize/secrete collagen fibers, ECM, initiate calcification
When trapped in their secretions (ECM) become osteocytes
Osteocytes
Mature/main bone cells, maintains bones daily metabolism
Osteoclasts
Huge cells from fusion of 50 monocytes (WBC)
Ruffled border releases lysosomal enzymes, breakdown ECM=bone resorption
Compact bone tissue
Few spaces=strongest
Found beneath periosteum of all bones/most diaphyses of long bones
Osteons (Haversian) systems
Repeating concentric lamellae arranges around osteonic (Haversian/central) canal