Calcium Ion (Intestinal)

Calcium ion (Ca²⁺) in the intestine is a critical target molecule involved in the regulation of calcium homeostasis within the body. Its absorption from the intestinal lumen into systemic circulation is essential for numerous physiological processes, including bone health, neuromuscular function, and intracellular signaling. Intestinal calcium absorption occurs via transcellular (active) and paracellular (passive) transport mechanisms. The transcellular pathway, primarily in the duodenum and upper jejunum, involves CaT1 channels, calbindin-D9k, and Ca²⁺-ATPase pumps, regulated by vitamin D. The paracellular pathway is a non-saturable process dependent on concentration gradients. The calcium-sensing receptor (CaSR), expressed along the intestine, modulates fluid secretion/absorption and potentially motility. Proper intestinal calcium uptake is crucial for preventing disorders like osteoporosis. Genetic polymorphisms affecting vitamin D receptor or related proteins can alter the efficiency of this process. The gut microbiota may also indirectly influence host calcium balance.

Other names

Ca2+ (Intestinal)Intestinal Calcium

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