Physiology Endocrinology and Reproduction 23d03791 Calcium absorption is from: A Proximal small intestine B Distal ileum C Middle small intestine D Ascending colon High-Yield Explanation Ans. (a) Proximal small intestine(Ref: Ganong, 25th ed/p.375)Active calcium absorption occurs mainly in the proximal small bowel (duodenum and proximal jejunum)