PHIS 206 1st Edition Lecture 35 Outline of Last Lecture I Diagram II Metabolism in the Brain III Hormones that are Major Players in Determining which State IV Insulin V Diabetes Mellitus VI Glucagon VII Fed v Fasting State Outline of Current Lecture I We Regulate 3 Hormones for Plasma II Plasma Calcium Levels III Parathyroid Hormone IV Bones V Parathyroid Hormone in Kidneys VI Parathyroid Hormone in Intestines VII Control of Parathyroid VIII Calcitonin IX Vitamin D X Normal Plasma Calcium Levels XI Deficiency in Vitamin D Calcium Parathyroid Hormone XII Parathyroid Hormone Disorders XIII Vitamin D Deficiency XIV Fracture Bones Current Lecture I We Regulate 3 Hormones for Plasma Parathyroid Hormone Calcitonin peptide Vitamin D steroid 99 of Ca in body is in the bones teeth 0 9 in soft tissues 0 1 in plasma 0 05 free in plasma ONLY PART WE REGULATE 0 05 bound in plasma II Plasma Calcium Levels Intestinal Absorption Renal Excretion These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Bones and Teeth Plasma Ca2 Levels Bones and Teeth III Parathyroid Hormone primary regulator peptide effects on bone renal excretion indirectly absorption of calcium of renal through lumen overall effect increase plasma calcium levels IV Bones like a lock tissue that is metabolically inert you might think BUT bone IS metabolically active matrix consists of collagen fibrous protein that makes up cartilage calcium phosphate makes bones hard and brittle bones mechanical collagen with calcium phosphate deposited on it called matrix matrix is constantly being dissolved and reformed constantly losing calcium in plasma constantly digesting collagen dissolution of bone is random but deposition occurs along the lines of stress compression thickest and most rapid forming along these lines called bone remodeling parathyroid causes increase in removal of calcium and phosphate into plasma promotes bone dissolution chronic deficiency results in loss of bone density V Parathyroid Hormone in Kidneys mobilizing calcium and phosphate so increasing levels increase calcium and prevent phosphate from precipitating when you add calcium you add phosphate increases reabsorption of calcium from nephron to plasma increases rate of excreting phosphate so major effect increase calcium and decrease phosphate end result decrease calcium phosphate in bones and teeth increase calcium phosphate in plasma does not affect plasma phosphate levels much VI Parathyroid Hormone in Intestines not direct effect absolute dependent on Vitamin D Activated Vitamin D o 2 transformations in liver and kidney o required to absorb calcium into lumen o parathyroid hormone promotes activation of Vitamin D in the kidney VII Control of Parathyroid no endocrine neural control secretion is direct response to plasma calcium levels VIII Calcitonin secreted by thyroid gland cells that secrete is called C cells decreases plasma calcium levels secretion by simple feedback physiologically a calcitonin is not important unless lactation IX Vitamin D doesn t do anything by itself no absorption need metabolic production Activated Vitamin D no Activated Vitamin D no Calcium Deficiency Vitamin D is a precursor to Activated Vitamin D Vitamin D deficiency hypercalcemic 2 Sources of Vitamin D synthesized in skin exposed to sunlight is not an adequate source of Vitamin D another source is in diet o most common source of Vitamin D X Normal Plasma Calcium Levels vary secretion of Parathyroid Hormone increase Parathyroid to promote phosphate excretion and calcium absorption in lumen promotes Vitamin D activation to increase calcium absorption in the gut XI Deficiency in Vitamin D Calcium Parathyroid Hormone bones lose density and become weak fragile use last bit to maintain normal plasma calcium levels XII Parathyroid Hormone Disorders hyperparathyroidism elevated plasma calcium levels reduced bone density muscle weakness depress neural activity poor memory kidney stones bone density decreases bones weaken hypoparathyroidism muscle excitability spasms complete lack fatal calcium so low that respiratory system goes into spasmic contractions XIII Vitamin D Deficiency reduced ability to absorb Vitamin D reduced bone density adults bones less rigid condition called Rickett s in children flexible bones osteoporosis rate of reduction at which new bone gets laid down around age 50 causes reduction in bone mass more common in women hunched back b c neck loses rigidity plasma calcium levels are normal younger women estrogen prevents it exercise builds bones and makes it less likely to get osteoporosis XIV Fracture Bones broken end decalcifies bone becomes flexible and sticky align it back but not touching just close enough to get the blood circulating over time soft gummy stuff calcifies so product is bone with a bump bone will be considerably thicker as it remodels gradually the bone will drift back but it will have a bend in it