Loss of bile salts in the colon affects water and salt reabsorption by causing:

• A. Increased water reabsorption
• B. Reduced water and salt reabsorption
• C. No change in water reabsorption
• D. Increased sodium absorption but not water

Answer: (B)

Bile salts in the colon promote colonic secretion and hinder absorption, so water and electrolyte reabsorption decreases. Normally the colon reabsorbs water by transporting sodium and other electrolytes; when bile acids reach the colon, they stimulate secretory pathways (increasing chloride secretion and water loss) and can irritate the mucosa, reducing the colon’s absorptive capacity. The net result is a secretory pattern with less water and salt being reabsorbed, producing more stool water. An increase in water reabsorption would contradict this secretory effect, no change wouldn’t reflect bile salt activity, and imagining increased sodium absorption without water doesn’t fit the disrupted absorption and secretory response caused by bile salts.