Question

1a) How do the epithelia between the esophagus and small intestine differ?

b) What are the functional reasons for the different structures?

c) What are the major structures of the digestive tract, in order, starting with the mouth?

d) What are the large glands associated with the digestive tract and where do the ducts from these glands enter the tract?

Answer 1

a The human esophagus consists of stratified squamous epithelium without keratin, a smooth lamina propria, and a muscularis mucosae.The small intestine is lined by a simple columnar epithelium which consists primarily of absorptive cells, with scattered goblet cells and enteroendocrine cells.

b  Because the epithelium of oesophagus is normally not exposed to dryness or to abrasion, it is non-keratinized. Scattered submucosal mucous glands provide lubrication. A well-developed muscularis provides peristaltic propulsion of food.Simple columnar epithelium lines much of the intestinal tract of the small intestine because its function is absorption of digested food

c

Food passes through the digestive system in the following order:

• Mouth.
• Esophagus.
• Stomach.
• The small intestine.
• Colon (large intestine)
• Rectum.

d Digestive glands includes salivary glands, pancreas, liver, gastric glands and intestinal glands. salivary glands, pancreas and liver are major glands.The larger duct ie the duct from liver and pancreas fuses with the common bile duct (carrying bile from the liver and gallbladder) just before entering the duodenum via a common opening (the hepatopancreatic ampulla)