One long tube

The idea

The alimentary canal is a long tube from the mouth to the anus whose different regions are specialised to perform different functions.

From mouth to anus

Food goes in at the mouth. What is left of it comes out at the anus.

What do you think lies between the two?

• A long tube with several regions
• A single empty bag
• Nothing, the two are joined directly

Visit each region

Open each tab to see what that region does.

Specialised regions

Food passes through one long tube, and the tube is not the same all along. Each region is specialised: the mouth crushes and wets the food, the stomach digests it, the small intestine completes digestion and absorbs it, the large intestine absorbs water, and the anus lets the waste leave.

The alimentary canal is a long tube from the mouth to the anus whose different regions are specialised to perform different functions.

Notes

The alimentary canal is a long tube from the mouth to the anus; its regions are specialised for different functions.

Check yourself

The alimentary canal is a long tube that runs from the ...

What does it mean that the regions of the canal are specialised?

Which region is the longest part of the alimentary canal?

Food leaves the stomach. Which region does it enter next?

• mouth to the stomach. The stomach is only one region of the canal; the tube goes on through the small and large intestines to the anus.
• stomach to the urinary bladder. The urinary bladder belongs to the excretory system, not to the alimentary canal.
• mouth to the anus — correct. Yes!
• Different regions perform different functions — correct. Yes!
• All regions do the same job. The book says that various regions are specialised to perform different functions.
• Only the mouth does any work on the food. The stomach and the intestines also act on the food, as the book describes.
• The stomach. The stomach is a large organ that expands when food enters, but the book calls the small intestine the longest part.
• The small intestine — correct. Yes!
• The food-pipe. The food-pipe carries food from the mouth to the stomach; the book names the small intestine as the longest part.
• The food-pipe. The food-pipe comes before the stomach: it brings food from the mouth to the stomach.
• The anus. The anus is the last opening of the canal; the small and large intestines lie between the stomach and the anus.
• The small intestine — correct. Yes!