ANSC 3270 Lecture Notes - Lecture 3: Extracellular Fluid, Cellular Compartment, Cholecalciferol
24 Apr 2019
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0. 9% in the cell memb and er in cells. 50% ionized ca = used by cells for signalling. 50% bound to protein or other molecules. Any fluctuation in the fluctuation in this concentration will affect intracellular signalling. Can have fluxes of ca from er or from outside the cell into the cytosol. Large difference in concentration of ionized ca between the extracellular fluid and the cytoplasm, and between er and cytoplasm. Low permeability of cell membrane to ca. Influx of ca is controlled by ion channels regulated by membrane potential or intracellular signalling. Changes in concentration cause changes in cell function. Controlled by 3 hormones: calcitonin, parathyroid hormone, also known as pth or parathormone, 1,25 (oh)2 cholecalciferol, active form of vit d, also known as calcitriol or 1,25-dihydroxyvitamin d. Parafollicular cells (c cells) in the thyroid glands. Ca sensing receptors on the cells surface. Ca sensing receptors on the cell surface. Low ca (< 8 mg/ml) increases pth secretion.
