e) Small intestine: It is a tube of about 7 meters in length, divisible into an anterior part called the duodenum, the middle part called jejunum and posterior part known as the ileum. The duodenum is a C-shaped structure. The liver and pancreas release their digestive jucies into this.

f) Large intestine: It is a short tube about 1.5 meters long. It is divisible into the anterior colon and the posterior part called rectum. The colon is differentiated into ascending, transverse, descending and sigmoid parts. At the junction of the ileum and colon, there is a blind pouch called the caecum ending into a small projection called the appendix. The rectum is the terminal part, about 12 cm long and opening outside as the anus. This is surrounded by the voluntary anal sphincter to control defecation.

(2) Associated glands : Apart from the gastric and intestinal glands embedded in the walls of the stomach and intestine, there are glands like salivary glands, liver and pancreas which pour their secretions into the alimentary canal.

(a) Salivary glands : There are three pairs of salivary glands, namely, sub-lingual, sub-maxillary and parotids opening into the mouth cavity as shown in Figure 16.7. They secrete saliva while food is being chewed in the mouth cavity.