BIOM 3200 Lecture Notes - Lecture 3: Collagen, Hypoparathyroidism, Intestinal Epithelium
4 Feb 2017
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Calcium salts along with phosphate provide the structural components of bone. Intracellular and extracellular calcium ions are essential for several normal biochemical processes: neuromuscular excitation, blood coagulation, hormone secretion, enzyme activity, fertilization. 99% is in the bones as hydroxyapatite. Calcium complexed with phosphate and citrate: 10% Associated with membranes in mitochondria, endoplasmic reticulum and plasma membrane. Intake: diet: 1/3 absorbed in small intestine, absorption is hormone regulated, body (cid:272)a(cid:374)(cid:859)t (cid:373)ake it a(cid:374)d (cid:449)ill lose it so it has to (cid:271)e repla(cid:272)ed. 3 hormones regulate movement of calcium between bone, kidney and intestine: parathyroid hormone (pth, calcitriol (vitamin d3, calcitonin. First 2 are most important in adults. Hypocalcaemia (too low: pth secretion increases (stimulate resorption to get ca2+ back in the blood. Hypercalcemia (too high: pth secretion decreases. Thyroid gland can be surgically removed but parathyroid cannot (essential for life) Parathyroids are seen in terrestrial amphibians onwards. 2 cell types: chief cells (produce pth) and oxyphils (function unknown)
