CHAPTER 23: Intestinal Absorption of Calcium Check Access

The absorption of calcium (Ca²⁺) from the gastrointestinal tract occurs through two distinct routes and is influenced by vitamin D (1,25-dihydroxycholecalciferol). The paracellular pathway describes the permeable movement of Ca²⁺ ions from the intestinal lumen into the blood through tight junctions. In contrast, the transcellular pathway is the sequential movement of Ca²⁺ ions from the intestinal lumen into the cytoplasm of the enterocyte, transport of apical Ca²⁺ to the basolateral side of the cell, followed by energy-dependent extrusion into the blood. These complementary pathways work to ensure optimal calcium absorption from the intestine independent of lumenal calcium concentration.