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Calcium

Description

endo Mind Map on Calcium, created by fatimaelfitouri on 12/06/2013.
fatimaelfitouri
Mind Map by fatimaelfitouri, updated more than 1 year ago
fatimaelfitouri
Created by fatimaelfitouri over 8 years ago
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Resource summary

Calcium
  1. Hypocalcaemia
    1. increase in nerve excitability
      1. cause tetany

        Annotations:

        • spasms
        1. if severe can cause death by asphyxiation
    2. hypercalcaemia
      1. reduces neuromuscular excitability
        1. lead to cardiac arrhythmias, lethargy and death
        2. causes
          1. 54% primary hyperparathyroidism
            1. 34% malignancy associated
              1. 12% other
            2. location
              1. 99% bones and teeth
                1. intercellular

                  Annotations:

                  • soluble in cytosol and nucleus.  insoluble in PM, ER and mitochondria  
                  1. extracellular

                    Annotations:

                    • extracellular fluid for  Blood clotting,  exocytosis and contraction   
                  2. PTH

                    Annotations:

                    • parathyroid hormone 
                    1. produced by chief cells of the parathyroid gland
                      1. 88a
                        1. synthesised as prep-pro PTH (115aa)
                          1. cleaved to proPTH
                            1. cleaved again to PTH

                              Annotations:

                              • cleaved in the liver 88aa half life 20mins  
                          2. secretion is inversely proportional to serum Ca
                            1. effects
                              1. increases bone resorption
                                1. increase renal Ca reabsorption
                                  1. increase Pi excretion
                                    1. increase production of Vit D
                                    2. PTHrP

                                      Annotations:

                                      • PTH related peptide
                                      1. 141,139,173aa

                                        Annotations:

                                        • alternate splicing 
                                        1. secreted in certain cancers causing humoral hypercalcaemia of malignancy
                                          1. similar to PTH
                                            1. widely expressed under normal conditions
                                              1. essential for normal skeletal development

                                                Annotations:

                                                • identified from KO studies 
                                              2. evolution
                                              3. Vitamin D
                                                1. biosynthesis
                                                  1. PTH increases transcription of 1 alpha hydroxalase gene in the renal proximal tubule
                                                    1. in the skin UVB forms preVitD3
                                                    2. carried in the plasma bound to specific globulin VitD binding protein (DBP)

                                                      Annotations:

                                                      • VitD is lipid soluble 
                                                      1. source
                                                        1. oily fish

                                                          Annotations:

                                                          • salmon 
                                                          1. milk
                                                          2. Deficiency
                                                            1. Rickets
                                                              1. secondary hyperparathyroidism
                                                                1. osteomalacia
                                                                2. actions
                                                                  1. increase net intestinal Ca2+ uptake
                                                                    1. increases calbindin expression
                                                                      1. increase bone resorption
                                                                        1. increases renal Ca reabsorption
                                                                      2. Calcitonin
                                                                        1. Parafollicular thyroidal “C cells''
                                                                          1. 32 aa peptide (from pro-calcitonin)
                                                                            1. reduces Ca plasma levels after a meal
                                                                              1. reduces osteoclast activity- reduces bone resorption
                                                                                1. Secretion inhibited by low Ca2+ levels in the blood
                                                                                2. plasma calcium
                                                                                  1. total ~ 2.5 mM (10mg/dl)
                                                                                    1. 35-40% bound to macromolecular proteins

                                                                                      Annotations:

                                                                                      • especially albumin
                                                                                      1. 5% complexed as salts

                                                                                        Annotations:

                                                                                        •    Ca2+ salts of bicarbonate, phosphate, sulphate & citrate.   
                                                                                        1. free ionised Ca2+ concentration is ~ 1.2 mM
                                                                                        2. Calcium sensing mechanism only senses free ionised Ca

                                                                                          Annotations:

                                                                                          • The Ca2+-sensing mechanisms that oversee Ca2+ homeostasis sense changes in free, ionised Ca2+ levels rather than total Ca2+ levels
                                                                                        3. renal failure
                                                                                          1. Factors affecting bone formation / Ca2+ metabolism
                                                                                            1. Calciotropic hormones

                                                                                              Annotations:

                                                                                              • affect calcium
                                                                                              1. PTH
                                                                                                1. Vit D3
                                                                                                  1. calcitonin
                                                                                                  2. Non-calciotropic hormones

                                                                                                    Annotations:

                                                                                                    • affect bone formation but not calcium 
                                                                                                    1. Glucocorticoids
                                                                                                      1. Growth hormone
                                                                                                        1. thyroid hormones
                                                                                                          1. estrogen
                                                                                                            1. insulin
                                                                                                              1. EGF, FGF, PDGF
                                                                                                                1. PGE2, osteoclast activating factor
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