Final answer:
The statement is false; it is the gastro-esophageal sphincter that prevents stomach acid from entering the esophagus, not the pyloric sphincter.
Step-by-step explanation:
The statement that the pyloric sphincter not constricting tight enough will lead to stomach acid leaking back into the esophagus is false. The pyloric sphincter is located at the lower end of the stomach and regulates the passage of partially digested food (chyme) from the stomach to the duodenum. It is the gastro-esophageal sphincter (or lower esophageal sphincter), not the pyloric sphincter, which prevents the contents of the stomach, including stomach acid, from traveling up the esophagus. When the gastro-esophageal sphincter does not close properly, or relaxes abnormally, the stomach acids can travel back up into the esophagus, causing acid reflux or heartburn. This condition, if chronic, may lead to gastroesophageal reflux disease (GERD).