NS 132 SQ 17 - Bone Health: Study Questions Synopsis: This...

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Bone Health: Study Questions Synopsis : This lecture looks at bone structure & strength. Causes & conditions for bone loss & osteoporosis are examined next, followed by suggested strategies for their prevention. Textbook readings: pages 322-327 I. Bone is living tissue [bone diagram ] a. Growth b. Remodeling Why do we say bone is living tissue? Bone is alive w/ living processes ( i.e. active growth in epiphesial plates & remodeling) in bone (not inanimate rock) . Bone comprises cells that need oxygen, nutrients, & blood supply. Growth What is mature bone composed ō? What is it composed ō early in life? How do bones grow in length? When do they stop? Early in life, bone is composed ō cartilage (protein). Mature bone is composed ō hydroxyapatite (calcium, phosphorous cpd.) . - collection ō minerals Ca + , P in protein matrix - protein matrix form - minerals strength Active growth occurs at epiphesial plates (ends ō long bones) & stops until EP close during teen yrs. - active growth ends = full length achieved - growth : middle → outward Remodeling What is remodeling? remodeling What are osteoblasts? What do they do? Osteoblasts are active cells that build ō bone & lay down protein matrix & minerals to create bone. What are osteoclasts? What do they do? Osteoblasts are active cells that dissolve bone & matrix & release bone minerals into bloodstream. What does remodeling allow bone to do? Remodeling allows bone to: - reshape itself - adapt to stresses (like muscle) - to heal injury ( e.g. broken bone) - serve as calcium reservoir (stores)
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II. Calcium a. Hormonal control b. Negative Calcium balance Calcium essential How closely are blood levels ō calcium maintained? Why? Blood Ca + concentration/levels are very tightly/closely regulated/maintained w/in maintained @ ± 3%. - take calcium out ō bone when needed & into bone when enough - maintained by set ō hormonal controls What are the functions ō calcium? Functions ō calcium are: 1) muscle contraction (if none, tetani) 2) blood clotting 3) signal transduction (nerve transmission) 4) enzyme functions/rxns. Hormonal control Low Ca ++ intake Low intakes ō calcium give rise to low blood levels ō calcium. What hormone does this cause to be released? Parathyroid gland releases PTH ( parathyroid hormone ). -
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This note was uploaded on 03/29/2008 for the course NUTRI SCI 132 taught by Professor Anderson during the Spring '08 term at Wisconsin.

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NS 132 SQ 17 - Bone Health: Study Questions Synopsis: This...

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