Chapter 6 - Bones & Skeletal Tissues PDF

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Chapter 6 - Bones & Skeletal Tissues Anatomical Divisions: 1. Axial Skeleton (center line) 2. Appendicular Skeleton

Classification of Bones by Shape: 1. 2. 3. 4.

Long Bones – humerus, femur Short Bones – carpals, tarsals, patella Flat Bones – sternum, scapula, cranial plates Irregular Bones – vertebrae, pelvic bones

Bone Structure ("Diploe" – sandwich structure) Flat (outside) --> compact bone (next inner layer) --> spongy bone (middle)

Features of Bones Periosteum - outside shaft of long bone around flat bone – Course CT *Functions: protection, isolates, contains osteogenic cells (stem cells) on inner surface (make new bone cells)* -rich in vascularization -"nutrient" forming – where nutrient artery & nerves enter bone -"Sharpeys FIbers" - collagen fibers penetrate bone surface Endosteum – thin delicate CT lines inside medullary cavity Red Marrow - "Hematopoietic Tissue" --> synthesis of blood cells *Location: spaces of "trabeculae" (bone needles) of spongy bone* Bone Markings – bumps, crevices, holes, protrusions

Living Cells in Bones (Osteo = "bone") 1. Osteogenic Cells – stem cells continually divide --> give rise rto osteoblasts & bone lining cells found in periosteum  and in endosteum 2. Osteoblasts – immature  bone cell that secretes  "osteoid" (part of non-living matrix) 3. Osteoctye – mature  brain cell maintains bone matrix; communicates to other bone cells for "bone remodeling" 4. Bone Living Cells – flat cells found on surface of bone; remodeling is NOT going on; **Maintain bone matrix** 5. Osteoclast – secrete enzymes & acids that dissolve & degrade bone matrix; derived from macrophages (immune cells); **multinucleate**

Structure of Compact Bone Tissue (inside a bone) Central canal – contains blood vessels & nerves Lacunae – cavities where living bone cells reside "Osteon" - unit of bone tissue growth in compact bone Canuliculae – tiny canals connecting lacunae, transport nutrients & waste Lanellae – ring like pattern of hard bone matrix

Chemical Composition of Bone Tissue Osteoid – organic part of bone matrix secreted by osteoblasts **organic compounds** --> collagen fibers --> glycoproteins **osteoid mixes w/ inorganic mineral salts (calcium, magnesium), give bone hardness**

*** Calcium + minerals --> hardness*** ***collagen fibers --> flexibility***...