Question

Which of the following regions of the alimentary canal of man does not secrete a digestive enzyme?
(a)Oesophagus
(b)Stomach
(c)Duodenum
(d)Mouth

Answer 1

Hint: It helps in passing the food to the stomach by a wave-like muscular movement called peristalsis. It is a 22- 25 cm long, tubular and muscular structure. It is also known as ‘food pipe.’

Complete answer:
The esophagus is a tubular pipe-like structure, it does not secrete any digestive enzyme. It runs downwards through the neck behind the trachea, passes through the diaphragm, and opens in the stomach in the abdomen.

Additional Information:
 -The mouth is a transverse slit-like structure bounded by two soft movable lips. It is the foregut part of the alimentary canal and is for the food ingestion. The mouth contains sublingual, submaxillary, and parotid glands, which secrete the enzyme salivary amylase.
-The stomach is the most distensible portion of the alimentary canal. It is the midgut part of the alimentary canal and is a J- shaped structure. The stomach is present at the upper left side of the alimentary canal, below the diaphragm, and is formed of three parts: cardiac stomach, fundic part, and pyloric antrum. The stomach helps in mechanical churning and digestion of protein.
-Duodenum is the widest, shortest (25 cm), and most flexed part of the small intestine. It is the midgut part of the alimentary canal and is a C-shaped structure. The bile-pancreatic duct opens in the duodenum. Duodenum itself secretes cholecystokinin hormone.
So, the correct answer is, ‘Oesophagus.’

Note:
 -The inner mucosa of the stomach is raised into longitudinal folds called oesophageal rugae, which close it to prevent the entry of air and expands to receive the food bolus.
- The alimentary canal is formed of three parts that are foregut, midgut, and hindgut including mouth to anus.