Ans3)Alimentary canal is the mucular passage from mouth to anus. Food ingested will undergo different processes during different parts of this canal. Regardless of their specialized tasks, wall of the alimentary canal displays a common structure.
It has four layers. From inside out they are mucosa, submucosa, muscularis propria and adventitia. As seen in the pic below.
Mucosa can be further divided in to innermost epithelium, surrounded by lamina propria and muscularis mucosa respectively.Lamina propria is a loose areolar tissue layer.
Submucosa is a loose collagenous tissue. It contains blood vessels,lymphatics and nerves.Between submucosa and muscularis propria there is a submucous plexus called as 'Meisner plexus' supplying the muscularis mucosa.
Muscularis propria consists of smooth muscle.Inner circular and outer longitudinal layers.Stomach has an exception of having an oblique muscle layer as the innermost muscle layer.Inbetween the two muscle layers another nerve plexus called ?Myenteric plexus? is present.
Outermost adventitial layer is formed by the visceral peritoneal layer.
Finally we can see that this common structure is modified in several ways in order to full fill the specific tasks of different regions of alimentary canal.
