Chemoreceptors monitor what in the digestive system?

• A. Stretch of the GI tract.
• B. Chemical contents in the digestive system.
• C. Pressure in the blood vessels feeding the GI tract.
• D. Light levels in the oral cavity.

Answer: (B)

Chemoreceptors in the digestive tract detect the chemical makeup of the contents inside the lumen, such as nutrients (amino acids, sugars, fatty acids), acidity (pH), and osmolarity. This chemical information guides digestion by triggering responses like gastric acid secretion, pancreatic enzyme and bile release, and adjustments in motility, all coordinated through the enteric and autonomic nervous systems and gut hormones (for example, secretin, gastrin, and cholecystokinin). This is different from stretch-sensitive receptors that monitor distension, or receptors that sense pressure in blood vessels or light in the mouth; those are not about the chemical content of the gut.