Bone Physiology. Bones are Classified by shape and structure. limbs. Carpals tarsals. vertebrae. Skull bones Ribs Sternum scapula. Epiphysis Epiphyseal Line Diaphysis Periosteum Articulating Cartilage. Anatomy of Long Bone. Compact Bone. Canaliculi Haversian Canal Lamellae Osteon.
Anatomy of Long Bone
Collagen fibers are not arranged in concentric rings. But the lamellae form rods called trabeculae. No Osteons or Haverian Systems are present.
Osteocyte – mature bone cells; recycle Ca and PO4
Osteoclasts– dissolve bone by secreting enzymes and acids. Release Ca to be returned to blood stream
Osteoblasts– cells that produce new bone cells referred to as osteogenesis
Osteoclasts remove matrix, osteoblasts adds matris.
When an osteoblast’s lacunae is calcified the cell becomes and osteocyte.
Resting Zone division
Growth along Epiphyseal Line division
Maturation/Hypertrophy Zone division
PTH Feedback Loop
Factors that help with Bone Deposit Feedback Loop
i.e. rickets results from Vitamin D deficiency
i.e scurvy – caused from a reduction in osteoblast activity
Appositional Growth over time. Feedback Loop
If blood Ca levels are low for an extended time, bones continually lose Ca.
Once bone density loss begins, women lose 8% of their bone mass every decade, men lose 3% every decade
Sex (females more affected than males; especially after menopasue)
Insufficient exercise or too much exercise
Poor diet (low in Ca and protein
Race: Black > bone density
Fibrocartilage Callus Formation Feedback Loop
Bony Callus Feedback Loop
Bone Remodeling Feedback LoopContinues 4 months to a yearRemoves excess material; a layer of compact bone is produced