BIOM 4030 Midterm: Calcium homeostasis notes

• School: University of Guelph
• Department: Biomedical Sciences
• Course: BIOM 4030
• Professor: Pawel Bartlewski

Document Summary

Intracellular and extracellular signaling (second messenger, contraction, hor(cid:373)o(cid:374)e release, (cid:271)lood (cid:272)lotti(cid:374)g, fertilizatio(cid:374) (cid:895) Bone: osteoblasts (build bone) and osteoclasts (break up bone) 20x more from bone than from diet. Gut: active and passive ca2+ absorption, bile/fecal excretion. Net daily intake: 100mg (10% of dietary ca2+) Muscle and other cells: ca2+ uptake for multiple cell functions. Pth release stimulated by low serum ca2+ levels. Parathyroid has calcium sensitive receptors, also found in renal tubules. Pth is se(cid:272)reted (cid:272)o(cid:374)ti(cid:374)uously, (cid:374)ot stored (cid:894)like steroid, (cid:271)ut it"s a peptide(cid:895) Decreases serum ca2+ levels (secreted in response to hypercalcemia) Inhibits osteoclast activity and reduces ca2+ reabsorption in distal tubules. 7-dehydrocholesterol in skin and diet + uv light cholcalciferol. Converted to 1,25-hydroxy-cholcalciferol and 24,25-cholcalciferol in kidney. Vitamin d stimulates active transport of ca2+ when dietary calcium is low via calbindin in duodenum. Also promotes passive transport in rest of small intestine/large intestine. Gh, igf-1, th increase bone mineralization and growth (use calcium)