PSL300H1 Lecture Notes - Lecture 13: Bone Resorption, Rankl, Calcitriol
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Psl300 notes: endocrine part 5: calcium balance (lecture 13) Total body calcium = intracellular + extracellular (ecf/plasma + bone) Calcium in bone is mainly crystals (hydroxyapatite) A small fraction is ionized and readily exchangeable\ Osteoclast sit on the bone like a suction cup. Hco3 goes into blood stream with cl- coming in. Osteoclasts resorb, osteoblasts form, osteocytes (retired osteoblasts) Sits on the back of the thyroid gland. If someone must have a thyroid surgery, it is important that the surgeon remembers to keep the parathyroid in place and not remove it. Parathyroid cells are exquisitely sensitive to changes in extracellular calcium concentration . Ca2+-sensing receptor on plasma membrane used to monitor extracellular ca2+ Remember that the gcpr that activates pl-c (phospholipase-c) is a gq coupled receptor. This results in 2 products: dag and ip3. Ip3 will cause stored calcium to released in the cell. Calcium will activate pla2 and increase vdr expression which will reduce pth synthesis.
