Which structure acts as a valve between the esophagus and stomach to prevent reflux?

Which structure acts as a valve between the esophagus and stomach to prevent reflux?

• A. Cardioesophageal sphincter
• B. Pyloric sphincter
• C. Epiglottis
• D. Goblet cells

Answer: (A)

The main concept here is the valve that prevents stomach contents from moving back into the esophagus. This role is played by the cardioesophageal (lower esophageal) sphincter, a ring of smooth muscle at the junction of the esophagus and stomach. It maintains a resting tone to keep the passage closed and relaxes briefly during swallowing to allow a food bolus to enter the stomach, forming a barrier against reflux. When this sphincter functions correctly, reflux is minimized; problems arise if it relaxes inappropriately or loses tone. The other options don’t fit this function: the pyloric sphincter lies between the stomach and duodenum; the epiglottis protects the airway during swallowing; goblet cells secrete mucus for protection, not regulate the esophagogastric junction.

The main concept here is the valve that prevents stomach contents from moving back into the esophagus. This role is played by the cardioesophageal (lower esophageal) sphincter, a ring of smooth muscle at the junction of the esophagus and stomach. It maintains a resting tone to keep the passage closed and relaxes briefly during swallowing to allow a food bolus to enter the stomach, forming a barrier against reflux. When this sphincter functions correctly, reflux is minimized; problems arise if it relaxes inappropriately or loses tone. The other options don’t fit this function: the pyloric sphincter lies between the stomach and duodenum; the epiglottis protects the airway during swallowing; goblet cells secrete mucus for protection, not regulate the esophagogastric junction.