BIOC34H3 Lecture Notes - Lecture 18: Cholecalciferol, Homeostasis, Reabsorption
Document Summary
Stimulates reabsorption of ca in kidneys, releases ca from bones blood. Produced when plasma ca is too low. Converts cholesterol 7-dehydrocholesterol vitamin d3 (by sunlight) . Low plasma ca levels 25-hydroxyvitamin d3 becomes calcitrol increases ca reabsorption in kidneys works @ gut to increase rate of ca uptake from intestines into blood. Produced by thyroid glands in response to high [ca] in blood plasma. 375 mg/ml for glucose: renal threshold: plasma concentration of a substance when it begins to appear in urine. Reabsorption fails to keep up w filtration. Glucose excretion starts when plasma gluc is so low (1. 8 mg/ml) cuz not all glucose in the kidney has access to glucose transport systems. Gluc remaining inside the kidney centre is not able to be reabsorbed. If a substance is filtered at glomerulus not reabsorbed or secreted amount filtered. Substance must be cleared from body via glomerular filtration.
