Fluid & Electrolyte Q 78

---

Chloride is absorbed in the:

  

    A. Stomach

    B. Bowel

    C. Liver

    D. Kidney

    

    

Correct Answer: B. Bowel

---

Chloride is absorbed in the bowel, mainly the duodenum and jejunum. Sodium chloride is absorbed from the intestinal lumen by several mechanisms, most prominently by cotransport with glucose and amino acids, and by Na+/H+ exchange, both of which move sodium from the lumen into the enterocyte.

---

Option A: Absorbed sodium is rapidly exported from the cell via sodium pumps – when a lot of sodium is entering the cell, a lot of sodium is pumped out of the cell, which establishes a high osmolarity in the small intercellular spaces between adjacent enterocytes.

Option C: Levels of chlorine closely parallel levels of sodium intake and output, since a primary source of both is sodium chloride, or common table salt. Chlorine is stored to a limited extent in the skin, subcutaneous tissues, and skeleton and constitutes two-thirds of the negatively charged ions (anions) in the blood.

Option D: The majority of the filtered chloride is reabsorbed with sodium during transport through the first portion of the tubule, the proximal tubule. The reabsorption of chloride in this segment occurs in two phases. Both of these active processes raise the intraluminal chloride concentration thus producing, in the later segments of the proximal tubule, the passive movement of chloride along a favorable concentration and electrochemical gradient.

---