I want a complete and detailed learning guide in gastroenterology from scratch to advanced level. Please teach me about all major and minor gastrointestinal diseases, including their causes, symptoms, diagnosis methods, and treatment options. Cover diseases like GERD, peptic ulcers, inflammatory bowel diseases (Crohn’s, ulcerative colitis), liver diseases (hepatitis, cirrhosis), pancreatitis, GI infections, GI cancers, functional disorders (IBS, motility issues), and more. Explain clinical presentations with real-life case examples, diagnostic techniques (endoscopy, imaging, lab tests), and step-by-step treatment plans including medications, endoscopic procedures, surgery, and lifestyle modifications (diet, exercise, stress management). Also, provide guidance on preventive care, patient counseling, follow-up management, and handling complications. Include the latest advances and evidence-based practices. Make the content practical, clear, and clinically relevant so I can confidently understand, diagnose, and manage GI diseases like a skilled gastroenterologist. Please structure the information logically, starting from basic anatomy and physiology, moving to diseases and treatments, and finishing with advanced clinical knowledge and case-based learning.