Digestive System: Alimentary Canal Overview

Alimentary Canal

• The alimentary canal is a long, continuous tube responsible for digestion and absorption of food.
• Starts at the mouth and ends at the anus.

Mouth

• Entry point for food.
• Chewing and mixing with saliva occur here.
• Saliva contains salivary amylase, an enzyme that breaks down starch into sugars like maltose.
• The tongue assists in mixing food with saliva.

Esophagus

• Muscular tube that transports food from the mouth to the stomach.
• Uses peristalsis (wave-like muscle contractions) to move food.

Stomach

• Muscular pouch that stores, mixes, and stirs food.
• Secretes gastric juice, containing hydrochloric acid, to break down food molecules.
• Gastric glands in the stomach wall produce these juices.

Small Intestine

• Divided into three parts: duodenum, jejunum, and ileum.
• Final stages of food breakdown occur here.
• Receives enzymes from the liver (bile) and pancreas (pancreatic juice).
• Inner lining contains millions of finger-like projections called villi, which absorb digested food and water.

Liver

• The largest gland in the body.
• Secretes bile, which aids in fat digestion in the small intestine.

Pancreas

• Secretes pancreatic juice, containing enzymes that aid in the breakdown of carbohydrates, proteins, and fats.

Large Intestine

• Absorbs water and stores feces.
• Leads to the rectum, which opens at the anus, where feces are eliminated (defecation).