AP BIOLOGY

Detailed explanation-1: -Q. The junction between oesophagus and stomach is guarded by sphincter which is also known as the lower oesophageal sphincter.

Detailed explanation-2: -The cardia is the opening from the esophagus into the stomach. The uppermost part of the stomach, located above the entrance of the esophagus, is the fundus.

Detailed explanation-3: -The lower esophageal sphincter at the top of the stomach regulates food passing from the esophagus into the stomach, and prevents the contents of the stomach from reentering the esophagus. The pyloric sphincter at the bottom of the stomach governs the passage of food out of the stomach into the small intestine.

Detailed explanation-4: -The cardia is the first part of the stomach, which is connected to the esophagus. It contains the cardiac sphincter, which is a thin ring of muscle that helps to prevent stomach contents from going back up into the esophagus.

Detailed explanation-5: -The lower sphincter, or cardiac sphincter, at the upper portion( cardia) of the stomach. This sphincter prevents the acidic contents of the stomach from moving upward into the oesophagous.