Overview
This lecture covers the anatomy, physiology, and medical terminology of the digestive system, including structures, functions, common diseases, and diagnostic procedures.
Digestive System Overview
- The digestive system breaks down food, absorbs nutrients, and eliminates waste.
- Major organs include mouth, pharynx, esophagus, stomach, small intestine, large intestine, and accessory organs (liver, pancreas, gallbladder).
Anatomy of the Digestive System
- The mouth includes the cheeks, tongue, palate (hard and soft), teeth, and uvula.
- The pharynx serves as a passageway for both food and air.
- The esophagus connects the pharynx to the stomach and uses peristalsis to move food.
- The stomach is divided into cardia, fundus, body, and pylorus; mixes food into chyme.
- The small intestine (duodenum, jejunum, ileum) is the primary site for digestion and absorption.
- The large intestine (cecum, colon, rectum, anus) absorbs water, forms feces, and eliminates waste.
- Accessory organs: liver (produces bile), gallbladder (stores bile), pancreas (secretes digestive enzymes).
Physiology of Digestion
- Digestive functions: ingestion, propulsion, mechanical digestion, chemical digestion, absorption, defecation.
- Propulsion moves food via swallowing and peristalsis.
- Mechanical digestion includes mastication and churning.
- Chemical digestion uses enzymes to break down food.
- Absorption mainly occurs in the small intestine.
- Defecation removes undigested waste.
Common Digestive Diseases and Disorders
- GERD: acid reflux from stomach to esophagus, causing heartburn.
- Cholecystitis: inflammation of the gallbladder, often due to gallstones.
- Cirrhosis: irreversible scarring of the liver due to disease or alcoholism.
- Esophageal cancer: cancer of the esophagus, risk factors include tobacco and alcohol use.
- Hepatitis (A, B, C): inflammation of the liver from viruses, toxins, drugs, or autoimmunity.
- Celiac Disease: immune reaction to gluten damaging small intestine.
- Crohn’s Disease & Ulcerative Colitis: chronic inflammatory bowel diseases.
- Colon cancer: malignant growth in colon, often diagnosed with colonoscopy.
- Hernia: organ/tissue protruding through muscle or connective tissue.
- IBS: irritable bowel syndrome, causes abdominal pain, bloating, and altered bowel habits.
- Polyps: benign growths in colon that may become cancerous.
Medical Specialties and Procedures
- Gastroenterology: specialty for diagnosing and treating digestive diseases.
- Upper/Lower GI Series: x-rays using barium to evaluate GI tract.
- Fecal Occult Blood Test: detects hidden blood in stool.
- Stool Culture: analyzes feces for abnormal bacterial growth.
- Esophagogastroduodenoscopy (EGD): endoscopic exam of upper GI tract.
Key Terms & Definitions
- Oral cavity — mouth area enclosed by cheeks, palate, and tongue.
- Uvula — tissue hanging from the soft palate limiting food entry to nasal cavity.
- Peristalsis — sequential muscle contractions moving food through the digestive tract.
- Chyme — partially digested food mixed with gastric fluids.
- Bile — fluid from liver aiding fat digestion.
- Cirrhosis — scarring of the liver.
- Sphincter — muscle ring controlling passage between GI tract sections.
- Mastication — chewing.
- Absorption — nutrient uptake into the body.
- Defecation — elimination of feces.
Action Items / Next Steps
- Review digestive system word parts and medical terms.
- Complete anatomy labeling and practice activities.
- Watch the video: "How your digestive system works" by Emma Bryce (TED-Ed).
- Study diseases, disorders, and diagnostic procedures related to the digestive system.