II. Physiology
- Images
- Calcium is the most common mineral found in the human body
- Bones and Teeth
- Metabolic processes
- Enzyme modulator (when bound to calmodulin)
- Neuromuscular Function and Nerve Impulses
- Blood Clotting Pathway
- Cell Movement
- Total body Calcium distribution
- Skeleton: 98%
- Circulating: 2%
- Free or ionized Serum Calcium (active): 50%
- Albumin-bound Serum Calcium (inactive): 50%
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Parathyroid Hormone (PTH) modulates Serum Calcium (via Activated Vitamin D)
- PTH promotes renal activation of Vitamin D to 1,25-dihydroxycholecalciferol (activated Vitamin D)
- Calcium intestinal absorption is directly increased by 1,25-dihydroxycholecalciferol
- Intestinal Calcium absorption is the primary mechanism for regulating body Calcium
- Bone resorption increases with 1,25-dihydroxycholecalciferol
- Renal Distal convoluted tubule Calcium reabsorption increases with 1,25-dihydroxycholecalciferol
- Calcium intestinal absorption is directly increased by 1,25-dihydroxycholecalciferol
- PTH levels rise and fall inversely with Serum Calcium
- PTH rises in response to Low Serum Calcium (Hypocalcemia)
- PTH falls in response to High Serum Calcium (Hypercalcemia)
- PTH inhibits renal phosphate reabsorption
- Serum Phosphate would typically rise with Calcium reabsorption in gut, Kidneys and with bone resorption
- However, PTH's inhibition of renal phosphate reabsorption prevents Hyperphosphatemia
- PTH promotes renal activation of Vitamin D to 1,25-dihydroxycholecalciferol (activated Vitamin D)
-
Vitamin D effects vary by concentration
- Low concentrations of Vitamin D
- Promotes bone calcification
- Increases Calcium gastrointestinal absorption and renal reabsorption
- Persistent Vitamin D Deficiency may result in Rickets
- High concentrations of Vitamin D
- Functions in similar way to Parathyroid Hormone
- Increases bone resorption
- Low concentrations of Vitamin D
- Other factors affecting Calcium levels (less significant than PTH and Vitamin D)
- Calcitonin
- Calcitonin increases bone mineralization
- Calcitonin decreases Serum Calcium
- Blood pH
- Acidosis promotes Hypercalcemia
- Decreased Calcium plasma Protein binding (Calcium is displaced by excess Hydrogen Ion)
- Alkalosis promotes Hypocalcemia
- Increased Calcium plasma Protein binding
- Hyperventilation (and associated alkalosis) may result in transient Tetany from Hypocalcemia
- Acidosis promotes Hypercalcemia
- Calcitonin
III. Associated Conditions
- Hypercalcemia
- Hypocalcemia
- Rickets in children (Osteomalacia in Adults)
- Tetany
IV. References
- Goldberg (2014) Clinical Physiology, Medmaster, Miami p. 31
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Definition (CSP) | condition in which there is a deviation or interruption in the processing of calcium in the body, its absorption, transport, storage, and utilization. |
Concepts | Pathologic Function (T046) |
SnomedCT | 267505006, 154752005 |
English | calcium disorder, Calcium disorder, Calcium disorder (NOS), Disorder calcium (NOS), calcium disorders |
Dutch | calciumstoornis (NAO), calciumstoornis |
French | Troubles calciques SAI, Trouble calcique, Perturbation calcique SAI |
German | Erkrankung Kalzium (NNB), Kalziumerkrankung, Kalziumerkrankung (NNB) |
Italian | Disturbo del calcio, Disturbo del metabolismo del calcio (NAS) |
Portuguese | Alteração do cálcio NE, Alteração do cálcio |
Spanish | Trastorno del calcio, Trastorno del calcio (NEOM) |
Japanese | カルシウム代謝障害(NOS), カルシウムタイシャショウガイNOS |
Czech | Porucha vápníku (NOS), Porucha vápníku |
Hungarian | Calcium betegség, Calcium anyagcsere betegség (k.m.n.), Calcium eltérés (k.m.n.) |
Ontology: Calcium ion (C0596235)
Definition (NCI) | The metabolically-active portion of calcium, not bound to proteins, circulating in the blood. |
Definition (NCI_CRCH) | Calcium ion requiring two electrons to return to its elemental state. |
Definition (CSP) | divalent cation essential in cellular signal transduction and the normal functioning of nerves and muscles; plays a role in blood coagulation and in many enzymatic processes. |
Concepts | Element, Ion, or Isotope (T196) , Pharmacologic Substance (T121) |
English | Ionized Calcium, Ca2+, Calcium Ion, Calcium ion, ion calcium, free calcium, calcium ions, calcium ion, CALCIUM CATION, Ca 2+, CA+2, Ca++, Calcium 2+, CA, Calcium cation, Calcium Cation, calcium cation, Free Calcium, Calcium Ions |