The Digestive System

• The Digestive System prepares food for use by all body cells.
• Digestion is the chemical breakdown of complex biological molecules into their component.
• Mechanical - Changes the physical form of food.
• Chemical - Changes the chemical composition of food with the aid of digestive system.
• The Digestive Tract - a long muscular tube with many sections and areas.
• Mouth - Food enters in the mouth or oral cavity.
• Esophagus - A straight muscular tube that is about 10 inches (25 cm) long, which connects the mouth with the stomach.
• Stomach - Has inner folds (rugae) that increases the surface area. J-shaped muscular sac.
• Food is mixed with gastric juices (hydrochloric acid and enzymes) secreted by the stomach walls.
• Pepsin - major enzyme, converts proteins into peptides in the presence of HCL.
• Mucus - lubricates food and protects the gastric lining from strong digestive juices.
• Chyme passes through the pyloric sphicter into the small intestine.
• Small Intestine - Long (20 ft.) coiled tube beneath the stomach.
• Duodenum - Upper part, about 10 inches, connected to stomach.
• Jejunum - about 8 ft.
• Ileum - about 12 ft.
• Mucosa (inner wall) - secretes several enzymes that acts on the food.
• Large Intestine (colon) - Larger diameter, but shorter (5 ft.) Water is absorbed from the undigested food making the waste harder until it becomes solid.
• Accesory Organs - Produce or store enzymes that helps in digestion.
• Liver - Largest gland of the body. Stores sugar and glycogen. Produces bile.
• Gall Bladder - Stores bile in between meals.
• Bile contains bile salts, pigments, cholesterol, and phospholipids.
• Pancreas - produces a juice that contains enzymes (amylase and insulin) to break down carbohydrates, fats and protein.
• • Path Of Digestion
  • Mouth
  • Esophagus
  • Stomach
  • Small Intestine
  • Large Intestine
  • Anus or Rectum
• Peristalsis propels food and liquid slowly down the esophagus into the stomach.
• Cardiac Sphincter - Relaxes to allow food into the stomach.
• Salivary Amylase - secretion of salivary glands. Contains in the mouth.
• Appendix - hangs on the right side of the large intestine.