Functions of the Digestive System

Functions of the Digestive System

• The digestive system provides nutrients to cells and body tissues through four processes: ingestion, digestion, absorption, and elimination.
• The system is also referred to as the gastrointestinal (GI) tract or the alimentary canal.

Layers of the Alimentary Canal

• The alimentary canal has four layers: mucosa, submucosa, muscularis, and serosa/adventitia.
• Mucosa: secretes gastric juices, absorbs nutrients, and protects tissue through mucus production.
• Submucosa: holds blood, lymphatic, and nervous tissues that nourish, protect, and communicate.
• Muscularis: has muscles that contract and relax in a wavelike movement called peristalsis.
• Serosa/Adventitia: outermost layer that has different names depending on its location.

Mouth and Salivary Glands

• The oral cavity includes the mouth, lips, cheek, tongue, palate, upper and lower jaws, teeth, gums, and enamel.
• Salivary glands produce saliva, which breaks down carbohydrates.
• Types of salivary glands: parotid, submandibular, and sublingual.

Pharynx and Esophagus

• The pharynx (throat) is divided into nasopharynx, oropharynx, and laryngopharynx.
• The esophagus is a muscular tube that transports food to the stomach.

Stomach

• The stomach is divided into three main sections: fundus, body, and pylorus.
• The pylorus has three parts: pyloric antrum, pyloric canal, and pyloric sphincter, which regulates the release of food into the small intestine.

Small and Large Intestines

• The small intestine includes the duodenum, jejunum, and ileum, where most nutrient absorption occurs.
• The large intestine, or colon, includes the cecum, appendix, and sigmoid colon, where water and electrolytes are absorbed.

Accessory Organs

• The liver produces bile, which emulsifies fats, and is composed of bilirubin and cholesterol.
• The gallbladder stores bile.
• The pancreas has exocrine and endocrine functions, producing digestive enzymes and hormones.

Other Terms

• Jaundice: a condition caused by a buildup of bilirubin in the blood.
• Ankyloglossia: a condition where the frenulum is too short or tight.
• Frenotomy: a surgical procedure to cut the frenulum.
• Pyloromyotomy: a surgical procedure to cut the pyloric sphincter.