PSIO 201 5th Edition Lecture 12 Outline of Last Lecture Bone Growth Outline of Current Lecture I Calcium Homeostasis II Hormones in Calcium Homeostasis A Calcitonin B Parathyroid Hormone C Calcitriol D Must know Questions E Hormones that Influence Growth Current Lecture Goal of Calcium Homeostasis regulate blood calcium within normal range 8 5 11 ml dl Why Membrane stability Blood clotting prevention Intracellular Activity How Control Calcium entry and exit from blood This is done by bone storage Intestinal Absorption Kidney Secretion Main Control for calcium is through blood bones just work as storage units Hormones in Calcium Homeostasis A Calcitonin tones down calcium in blood Stimulus is high levels of blood calcium Source is from thyroid gland Target Tissues include bones kidneys and intestines Action goal is to decrease blood calcium 1 Inhibit osteoclast activity to decrease blood resorption 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 2 Increase excretion of calcium in kidneys 3 Inhibit absorption of calcium of intestine B Parathyroid Hormone Increase Blood Calcium Stimulus is low levels of blood calcium Source is from Parathyroid Gland Targeted Tissues include bones kidneys and intestines Goal is to increase calcium levels 1 Stimulate osteoclast activity 2 Decrease excretion of calcium in Kidney 3 Stimulate intestinal absorption of calcium to promote Calcitriol Active Vitamin D C Calcitriol Active form of Vitamin D Increase Blood Calcium Vitamin D is a steroid hormone derived from cholesterol Active form of Vitamin D is produces in Kidney Source comes from skin by UV light stimulus 1 UV light transforms into Vitamin D3 2 Vitamin D3 is carried to intestines and blood 3 Then goes to Liver to the Kidneys to make Calcitriol Only Parathyroid Hormone and Low Blood Calcium can activate this process Action 1 Stimulate osteoclast activity 2 Decrease excretion of calcium in Kidney 3 Stimulate intestinal absorption of calcium to promote Calcitriol Active Vitamin D How much Calcium should an average adult take 1000 mg day If calcium levels are little to none and Parathyroid Hormone and Calcitriol are not active what happens Osteoclasts will be stimulated to maintain blood Ca2 What is the role of Exercise To reach the fracture threshold later in life Diseases Pituitary Dwarfism low levels of somatropin Pituitary Giantism hypertension of somatropin Acromegaly appositional growth of width Hormones that Influence Bone a Calcitonin b Parathyroid c Somatropin Growth Hormone d Estrogen and Testosterone Somatropin Stimulates cell growth and protein synthesis Stimulates formation of insulin through osteoblast activity Estrogen and Testosterone Stimulate osteoblast for growth Levels increase at puberty Closure of epiphyseal plate
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