The small intestine continues digestion and absorbs nutrients. Western tradition places the intestines under Virgo, the sign of sorting and assimilation, and the correspondence is a good fit for what the organ does, though it was arrived at from the sign's general character rather than from physiology. In Chinese medicine the small intestine, xiao chang, is the fu paired with the heart and belongs to the fire phase, and its stated function is the separation of the pure from the impure, sending the clear upward and the turbid down to the large intestine and bladder. That the heart should be paired with the small intestine looks arbitrary from a western standpoint and is entirely consistent within the five-phase scheme, which is precisely the point: the pairings follow the phases, not the anatomy.
Ayurveda assigns digestion in the small intestine chiefly to Pachaka Pitta, the same seated digestive fire noted for the gall bladder and stomach, treating the whole upper digestive tract as the working ground of one subdosha rather than dividing its function organ by organ as the Chinese scheme does. The small intestine also carries a documented piece of surgical history distinct from either tradition: successful resection and repair of the small bowel, difficult because of the risk of infection before antisepsis, became reliably survivable only in the later nineteenth century, following the antiseptic techniques introduced by Joseph Lister from 1867, a comparatively recent achievement given how ancient the organ's symbolic and theoretical history is.
Sources Christian AstrologyWilliam Lilly with The Roots of Ayurveda: Selections from Sanskrit Medical WritingsDominik Wujastyk