The human alimentary canal is a long, muscular tube that runs from the mouth to the anus. It is responsible for the digestion and absorption of food and the elimination of waste.

The composition of the human alimentary canal includes the following:

1. Mouth: The mouth is the starting point of the alimentary canal. It contains the tongue, teeth, and salivary glands.

2. Pharynx: The pharynx, or throat, is a muscular tube that connects the mouth to the esophagus.

3. Esophagus: The esophagus is a muscular tube that connects the pharynx to the stomach.

4. Stomach: The stomach is a muscular sac that stores and breaks down food using stomach acid and enzymes.

5. Small intestine: The small intestine is a long, narrow tube that is responsible for the majority of nutrient absorption. It is divided into three parts: the duodenum, jejunum, and ileum.

6. Large intestine: The large intestine is responsible for absorbing water and electrolytes and forming feces. It is divided into four parts: the cecum, colon, rectum, and anus.

7. Liver: The liver is an accessory organ that produces bile, which helps with the digestion and absorption of fats.

8. Pancreas: The pancreas is an accessory organ that produces digestive enzymes and hormones such as insulin.

In summary, the human alimentary canal is a complex system that is responsible for the digestion, absorption, and elimination of food. It is composed of several organs and accessory organs that work together to ensure that the body receives the nutrients it needs to function properly.