How Well Do You Know Your Digestive System?

The Digestive System

• Food needs to be crushed and wetted in order to pass smoothly through the digestive tract.
• Saliva, secreted by salivary glands, contains an enzyme called salivary amylase that breaks down starch into simple sugars.
• Peristaltic movements, rhythmic contractions of muscles in the canal, move food along the digestive tube.
• The stomach mixes food thoroughly with digestive juices and contains gastric glands that release hydrochloric acid, pepsin, and mucus to aid in digestion.
• The sphincter muscle regulates the exit of food from the stomach into the small intestine.
• The small intestine is the site of complete digestion of carbohydrates, proteins, and fats, and receives secretions from the liver and pancreas.
• Bile juice from the liver alkalizes the acidic food and breaks down fats into smaller globules.
• The pancreas secretes pancreatic juice with enzymes like trypsin and lipase to digest proteins and emulsified fats.
• The walls of the small intestine contain glands that secrete intestinal juice to convert proteins, complex carbohydrates, and fats into amino acids, glucose, and fatty acids and glycerol.
• Digested food is absorbed by villi, finger-like projections in the inner lining of the small intestine, and transported to cells of the body for energy, tissue building, and repair.
• Unabsorbed food is sent to the large intestine where water is absorbed and the rest is eliminated through the anus.
• The exit of waste material is regulated by the anal sphincter.