PSL300H1 Lecture Notes - Lecture 4: Parafollicular Cell, Membrane Protein, Distal Convoluted Tubule
Document Summary
Cells responsible for bone growth/turnover: osteoblast (bone forming, osteocyte (maintain matrix) - hydroxyapatite found here, osteoclasts (bone resorption) - have extra nuclei because formed from the fusion of cells, calcium turnover/year = 100% in infants, 18% in adults. Osteoclasts: secrete protons into sealed off areas, breakdown of bones -> blood capillaries nearby so ca and phosphate can go into the blood stream, area of bone resorbtion, good to have coordination between osteoclasts and osteoblasts. Bone dynamics (~100 days): osteroclasts resorb, osteoblasts form, osteocytes (retired osteoblasts: resting phase, resorption- osteoclasts break down lining cells of bone, cavity made by osteoclasts, formation and repair by osteoblasts (new bone formed) Switch happens very rapidly @ about 1. 22 mm [free ca2+] in blood. Pth increases plasma [ca2+] by actin directly on bone and kidney: does not act on osteoclasts -> works on osteoblasts to increase rankl and decrease.
