Solution :
a). The path from mouth to the duodenum is :
Oral cavity ---- Oropharynx ---- Laryngopharynx ---- Esophagus ---- lower esophageal sphincter --- Stomach ---- Pyloric sphincter ---- Duodenum.
b). The digestive functions of the organs are :
ORAL CAVITY
The saliva in the oral cavity or the mouth keeps the mouth mist and it helps in food digestion. The salivary amylase converts the stretch into the maltose.
STOMACH
The stomach produces acidic pH and it helps to break the proteins in the food by the enzyme, Pepsinogen.
DUODENUM
In the duodenum, the chyme is mixed with the enzyme, bile and the pancreatic juice which helps in digestion.
c). In the gastroesophageal reflux, the lower sphincter does not function properly and that is why the gastric content that contains the acid and the pepsin regurgitate into the end of lower esophageal. This area is not an acid resistant, so the ulceration takes place.
d). Elevation of a head-end of the patient's bed, so that the gravity stops in the upward motion of the esophageal contents. The potent acid inhibiting agents like the Omeprazole.