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Calcium regulation in the human body. [6]The plasma ionized calcium concentration is regulated within narrow limits (1.3–1.5 mmol/L). This is achieved by both the parafollicular cells of the thyroid gland, and the parathyroid glands constantly sensing (i.e. measuring) the concentration of calcium ions in the blood flowing through them.
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Calcium homeostasis. The plasma ionized calcium (Ca 2+) concentration is very tightly controlled by a pair of homeostatic mechanisms. [60] The sensor for the first one is situated in the parathyroid glands, where the chief cells sense the Ca 2+ level by means of specialized calcium receptors in their membranes.
A diagrammatic representation of the movements of calcium ions into and out of the blood plasma (the central square labeled PLASMA Ca 2+) in an adult in calcium balance: The widths of the red arrows indicating movement into and out of the plasma are roughly in proportion to the daily amounts of calcium moved in the indicated directions.
The US Institute of Medicine (IOM) established Recommended Dietary Allowances (RDAs) for calcium in 1997 and updated those values in 2011. [6] See table. The European Food Safety Authority (EFSA) uses the term Population Reference Intake (PRIs) instead of RDAs and sets slightly different numbers: ages 4–10 800 mg, ages 11–17 1150 mg, ages 18–24 1000 mg, and >25 years 950 mg. [10]
Idiopathic hypercalcinuria (IH) is a condition including an excessive urinary calcium level with a normal blood calcium level resulting from no underlying cause. [1] IH has become the most common cause of hypercalciuria and is the most serious metabolic risk factor for developing nephrolithiasis. [1]
Though calcium is the most plentiful electrolyte in the body, a large percentage of it is used to form the bones. [14] It is mainly absorbed and excreted through the GI system. [ 14 ] The majority of calcium resides extracellularly, and it is crucial for the function of neurons , muscle cells , function of enzymes , and coagulation . [ 14 ]
Calcium-binding proteins have specific domains that bind to calcium and are known to be heterogeneous. One of the functions of calcium binding proteins is to regulate the amount of free (unbound) Ca 2+ in the cytosol of the cell. [1] The cellular regulation of calcium is known as calcium homeostasis.