CHP7 Bone Tissue

A tooth braces pull tooth towards desired position

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Unformatted text preview: organs) or arteries (= arteriosclerosis) calculus arteriosclerosis Mineral resorption Mineral Min resorption= process of dissolving bone & releasing process minerals into blood stream for other uses minerals • Osteoclasts @ “ruffled border” use H2 pumps in cell membrane to secrete H+ into space btwn osteoclast & bone membrane • Cl- follow by electrical attraction; HCl forms in extracellular space (pH ~4) to dissolve bone minerals space • Enzyme (acid phosphatase) secreted by osteoclasts digests sts collagen fibers collagen Orthodontic braces reposition teeth by inc pressure on one Orthodontic side of a tooth (braces ‘pull’ tooth towards desired position) position) • Jaw bone is remodeled (& teeth repositioned) because inc Jaw pressure stimulates osteoclasts & decreased pressure on far side of tooth stimulates osteoblasts (to rebuild bone behind ‘moved’ tooth) behind Calcium & Phosphate Homeostasis Calcium Functions of PO43-~ • Component of DNA, RNA, ATP, phospholipids, & acidbase buffers • Adults have ~500-800 g P, w/ ~90% in bone • In blood plasma, [PO43-] ~ 3.5-4.0 mg/dL & occurs in 2 3.5-4.0 -2 forms: HPO4 -2 & H2PO4forms: Functions of Ca2+~ • Required for communication btwn neurons, muscle Required contraction, blood clotting & exocytosis clotting • [Ca2+] plasma ~ 9.2-10.4 mg/dL; ~45% in ionic form (Ca 2+) & remainder is ‘inactive’ Ca bound to plasma proteins (Ca reserves) reserves) Ion Imbalances Ion Changes in [Ca]= hypocalcemia (deficiency) & hypercalcemia Changes hypocalcemia hypercalcemia • Hypocalcemia causes muscle tremors/spasms= excessive Hypocalcemia firing of nervous tissues to muscle fibers (inability to relax= tetany) tetany • Causes include Vit-D deficiencies, diarrhea, thyroid tumors, Causes underactive parathyroid; pregnancy & lactation are risk factors underactive Tetany= 1st indicators include carpopedal spasms of hands & feet feet • If [<6 mg/dL] larynx muscles contract (= laryngospasm) & If laryngospasm may cause suffocation may • Ca2+ normally binds to anions on cell surface, helping to keep cell ‘more –’ inside & ‘more +’ outside membrane cell • Less Ca, Na channels open easier & stay open longer…. Less excitation & longer stimulation of neurons Ion imbalances (cont.) Ion Hypercalcemia= excessive Ca binds to cell surface…Na excessive channels reluctant...
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