Gastrointestinal System and Related Health Issues

Pre-Quizzes in Education

• Educational psychology supports the use of pre-quizzes to enhance learning.
• They aid memory formation, preparing students for discussion in lectures.

Gastrointestinal (GI) Tract Overview

• Major Functions:
• Digest food
• Absorb nutrients
• Motility through peristaltic waves
• Secretion of about 9 liters/day of fluids, enzymes, and bile into the GI tract; only 6 ounces are reabsorbed by the body.
• Digestive Process:

1. Ingestion: Mouth, esophagus, stomach (first digestion)
2. Absorption: Small intestine (duodenum, jejunum, ileum - 90% absorption occurs here)
3. Elimination: Large intestine (colon)

Structure of the GI Tract:

• Upper GI: Mouth, esophagus, stomach
• Middle GI: Duodenum, jejunum, ileum (total of about 9 feet long)
• Lower GI: Cecum, colon (1.5 feet long)
• Over 2-6 pounds of bacteria reside in the colon contributing to immune function and digestion.

Digestive Health and Bacteria:

• Role of bacteria in digesting vitamins like Vitamin K and D.
• Ileocecal valve prevents backflow into the small intestine, essential for maintaining gut health.

Accessory Organs:

• Liver: Produces bile and performs detoxification; knowledge of liver anatomy is crucial.

Emesis (Vomiting) Process:

• Involves multiple systems: the sympathetic system can trigger vomiting due to pain or anxiety.
• Emetic reflex controlled by various brain areas including the medulla.

Types of Diarrhea:

1. Osmotic Diarrhea: Caused by poorly absorbed solutes that pull water, e.g., lactose intolerance.
2. Secretory Diarrhea: Triggered by toxins or infections, e.g., cholera leading to severe fluid loss.
3. Altered Motility: Increased peristalsis due to stress.

Abdominal Pain:

• Dull, squeezed pain (visceral) varies according to organ involvement (e.g., sharp pain indicates inflammation).

Esophagus:

• A collapsible tube (~10 inches) with a critical role in swallowing and peristaltic motion.
• Dysfunctional signs include dysphagia (difficulty swallowing) and achalasia (failure of lower esophageal sphincter to relax).

Gastroesophageal Reflux Disease (GERD):

• Caused by relaxed lower esophageal sphincter allowing stomach acid to penetrate the esophagus.
• Symptoms include burning chest pain and potential heart attack mimicking symptoms.

Peptic Ulcers:

• Erosion in the wall of the GI tract popular in the stomach and duodenum.
• Risk factors include H. pylori, NSAIDs, and smoking.

Inflammatory Bowel Disease (IBD):

• Crohn's Disease: Can affect any GI area with skip lesions, causing abdominal pain, diarrhea, and malabsorption.
• Ulcerative Colitis: Affects only the colon, leading to bloody diarrhea and increased cancer risk.
• Both conditions show an immune response to gut bacteria, could be triggered by antibiotics or diet.

Cholecystitis and Cholelithiasis:

• Cholecystitis: Inflammation of the gallbladder, usually from a blocked bile duct.
• Cholelithiasis: Formation of gallstones, increasing risk from obesity and diet.

Pancreatitis:

• Acute: Reversible inflammation usually due to gallstones or alcohol; symptoms include severe upper abdominal pain and fever.
• Chronic: Irreversible damage from repeated inflammation leading to diabetes over time.

Liver Overview:

• Largest internal organ, performs vital detox and metabolic functions (e.g., synthesizing bile, blood clotting factors).
• Hepatitis can arise from several viral sources, leading to liver inflammation, jaundice, fatigue.

Cirrhosis:

• End-stage liver disease with significant fibrosis often due to chronic alcohol use or fatty liver disease (NAFLD).
• Complications include portal hypertension, ascites (fluid accumulation), and risk for liver cancer.