Human Digestive System Anatomy

Importance of Eating

• A healthful diet satisfies three needs

Digestive System

• Anatomy of the digestive system: Mouth (Oral Cavity), Pharynx, Esophagus, Stomach, Small Intestine, Large Intestine
• Digestion occurs in specialized compartments housing hydrolytic enzymes

Mouth (Oral Cavity)

• Anatomy: 8-11
• Physiology: teeth crush food into smaller pieces, mixing with saliva that contains enzymes to break down carbohydrates

Pharynx

• Anatomy: 1-3
• Physiology: food is swallowed, passing through the pharynx, which separates the digestive and respiratory systems

Esophagus

• Anatomy: Figure 21.6
• Physiology: peristalsis moves food boluses into the stomach, squeezing food along to the stomach

Stomach

• Anatomy: Food enters at the cardioesophageal sphincter, empties into the small intestine at the pyloric sphincter
• Physiology: stores food, breaks it down with acid and enzymes

Small Intestine

• Anatomy: extends from the pyloric sphincter to the ileocecal valve, has three parts: Duodenum, Jejunum, Ileum
• Physiology: site of nutrient absorption into the blood, final and complete digestion of food happens here
• Microvilli increase the surface area to facilitate nutrient absorption

Large Intestine

• Anatomy: Larger in diameter, but shorter than the small intestine, has four parts: Cecum, Colon, Rectum, Anus
• Physiology: absorbs water, eliminates indigestible food from the body as feces, reclaims water
• Goblet cells produce mucus to act as a lubricant

Colon

• Bacteria in the colon are harmless unless they escape into the abdominal cavity
• Some bacteria produce Vitamin K, which is absorbed through the intestinal wall

Rectum and Anus

• Rectum: stores the feces until defecation, using peristaltic movements during elimination
• Anus: an opening at the far-end of the digestive tract, is the exit point for the waste material

Learn about the structure and function of the human digestive system, from mouth to small intestine. Understand the importance of a healthful diet and how digestion occurs in specialized compartments.