PSIO 201 5th Edition Lecture 9 Outline of Last Lecture Skeletal System Outline of Current Lecture I Composition of Bone II Bone Modeling and Remodeling III Goals of Modeling Remodeling IV Composition of Bones 2 Current Lecture Osteoblasts build bone Osteoclasts Break down bone Osteogenic cell makes osteoblast makes osteocyte osteoclasts are separate organism 1 Osteoblasts still immature cell involved in bone formation and synthesis of collagen and calcification 2 Osteocytes mature cell maintains homeostasis and senses damage in bone maintains bone tissue and signals for repair 3 Osteoclast breaks down bone resorption dissolves matric through enzymes and acids Helps regulate calcium in the blood Calcium and proteins must pass through the cell process known as trancytosis Bone Modeling Constructions of bone from scratch formed by osteoblasts Bone Remodeling reconstruction first bone is resorbed and then formed in same location by osteoblasts This process happens throughout entire life Goals achieve strength for loading and lightness During growth goal is to achieve peak strength by removing damaged bone During remodeling 1 Bone is able to detect location and magnitude of damage by use of osteocyte These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute 2 The Osteoclast removed the damage 3 The Osteoblast replaces the old bone micro and macro fixes Remodeling goes through 5 stages of reconstruction 1 2 3 4 5 activation preosteoclasts differentiate and mature into active osteoclasts resorption osteoclasts digests minerals in matrix removing old bone Reversal ends resorption recruits osteoblasts Formation osteoblasts synthesize new bone matrix Quiescence osteoblasts rest bone lining for new bone completion Composition of Bone 2 Organic Substances Ground substances GAGS Glycoproteins polysaccharide and protein Negatively charged tap water Collagen fibers type 1 fibrous protein arranged in helical form very resistant provides flexibility Type 1 Collagen Tropocollagen 3 twisted in helical form inside fibers are microfibrils Fibril Fibers Microfibril found in ECM Inorganic Substances Water Hydroxyapatite mineral formed by plates Salts
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