Chapter 7
Bones and Skeletal system
Outline:
1. Cartilage
 Hyaline—frosted glass, provide support and flexibility, articular-covers end of
bones, coastal-connect ribs to the sternum.
 Fibrocartilage---has more parallel rows of chondrocytes with collagen fibers,
e.g. menisci of the knee and dics inbetween the vertebrae
 Elastic cartilage---more elastic fibers than hyaline, e.g., external ear.
Growth of cartilage—from outside-appositional, from inside-interstitial
2. Classification of bones-206 bones of human skeleton divided into two division
 Axial skeleton
 Appendicular skeleton
3. Functions of skeletal system:
 Support-provides structural support for entire body
 Storage of minerals and lipids-minerals like calcium and phosphate, lipids
are stored in bones as yellow bone marrow. Lipids are energy reserves
 Blood cell production-all the blood elements are produced by red bone
marrow
 Protection-protect many soft tissues and organs e.g., Ribs, skull and
vertebral column
 Leverage-bones functions as levers that can change the magnitude and
direction of the forces generated by skeletal muscles
4. Bone Shapes:
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Sesamoid---shape like sesame seed-patella
Flat---thin flat like sternum and skull
Irregular---complicated shape-vertebrae
5. Bones are classified as
 Long bones---Femur, humarus, ulna, radius
 Short bones---cube shaped-wrist and ankle
 Sesamoid---shape like sesame seed-patella
 Flat---thin flat like sternum and skull
 Irregular---complicated shape-vertebrae
6. Bone Markings:
 Tuberosity
 Crest
 Trochanter
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Line
Epicondyle
Spine
Process
7. BoneTexture:
 Spongy
 Compact
8. Bone cells
 Osteoblast (from osteoprogenitor cells)
 Osteocytes
 Osteoclast
9. Structure of Long bone:
 Diaphysis
 Epiphysis
 Membranes
10. Structure of Short, irregular and flat bones
11. Microscopic anatomy of Compact bone
 Osteon or Haversian system --- is the structural unit
 Lamellae
 Canaliculi
 Haversian canal
 Volkmann’s canal
12. Spongy bone-Matrix - a meshwork of supporting bundles of fibers called
trabeculae. Trabeculae branch thus creating open meshwork. There are no
capillaries in the matrix. Nutrients reach by diffusion along canaliculi that open
onto the surfaces of trabeculae. Spongy bone may contain yellow bone marrow.
13. Chemical composition of bone
 Organic components—osteoblasts, osteocytes, osteoclasts, osteoid-makes
matrix-ground substance made up of glycoproteins and collagen fibers-give
strength to the bone
 Inorganic--- hydroxyapatites or mineral salts like calcium phosphates
14. Bone development:
http://www.youtube.com/watch?v=x0TASU2LNa0
http://www.youtube.com/watch?v=p-3PuLXp9Wg
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Intramembranous-osteoblast differentiate within mesenchymal connective
tissue. –occurs in the deeper layers of dermis. Example-flat bone of the skull
and mandible.
Endochondrial-most bones originate as hyaline cartilages and are replaces by
bone through process of endochondral ossification.
Appositional growth-bone development in diameter.
Epiphyseal plate-present till adolescent then calcified,
15. Postnatal Bone growth:
 Growth zone
 Transformation zone
 Osteogenic zone
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Bone Homeostasis: Control of remodeling-Parathyroid hormone-when calcium
level declines-by the activity of osteoclast cells.
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Calcitonin-(produced by thyroid gland) when calcium levels rise-inhibits bone
reabsorption-fall
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Hormone Calcitriol, synthesize in the kidneys, is essential for normal calcium and
phosphate ion absorption in GI tract.
Vitamin C must be present in the diet –it is required for certain key enzymatic
reactions in collagen synthesis, osteoblast differentiation. Condition scurvy is a
loss of bone mass and strength.
Growth hormone (stimulate protein synthesis) produced by pituitary gland and
thyroxine from thyroid gland stimulate bone growth.
16. Fractures: In a small fracture blood vessels are broken and extensive bleeding
occurs. Large blood clot-fracture hematoma.
17. Periosteum and endosteum undergo rapid cycles of cell division and daughter cell
migrate into the fracture zone.
http://www.cliffsnotes.com/sciences/anatomy-and-physiology-quizzes
terminology for skeletal system
http://quizlet.com/15566554/kinesiology-chapter-4-bones-and-landmarks-on-bones-flashcards/