Lecture Discovering nutrition - Chapter 3: The human body: From food to fuel

Chapter 3 presents the following content: Taste and smell: the beginnings of our food experience, the gastrointestinal tract, overview of digestion: physical and chemical processes, overview of absorption, assisting organs, putting it all together: digestion and absorption, circulation of nutrients, signaling systems.

Chapter The Human Body: From Food to Fuel • Taste and Smell: The Beginnings of Our Food Sight, smell, thought, taste, and sound Experience – Trigger a set of responses that prepare the digestive tract to receive food The Gastrointestinal Tract • Variety of functions, including: – Ingestion of food – Transport of ingested food – Secretion of digestive enzymes, acid, mucus, and bile – Absorption of end products of digestion – Movement of undigested material – Elimination of digestive waste products The Gastrointestinal Tract • Several layers to the GI tract, including – Mucosa – Circular muscle – Longitudinal muscle – Sphincters Overview of Digestion • Physical movement – Peristalsis • • – Wavelike, muscular contractions Transport food and nutrients along the GI tract Segmentation • • Series of muscular contractions in the small intestines Divides and mixes the chyme Overview of Digestion • Chemical breakdown – Enzymes • – Proteins that catalyze chemical reactions Other secretions • Acid • Base • Bile • Mucus Putting it All Together: Digestion and Absorption • Large Intestine – Absorption • • • – Water Sodium, potassium, and chloride Vitamin K (produced by bacteria) Elimination Circulation of Nutrients • • Vascular system – Veins and arteries – Carries oxygen and nutrients to tissues – Removes wastes Lymphatic system – Vessels that drain lymph – Empties into the bloodstream near the neck Circulation of Nutrients • Excretion and elimination – Lungs • – Excrete water and carbon dioxide Kidneys filter blood • Excrete waste; maintain water and ion balance • Signaling Systems: Command, Control, and Nervous system Defense – • Regulates GI activity • Enteric nervous system • Autonomic nervous system Hormonal system – Increases or decreases GI motility and secretions – Influence your appetite • Signaling Systems: Command, Control, and Immune system Defense – Protects us from foreign invaders – Role of GI tract • Barrier • Immune response • – Natural killer cells – Macrophages Location of lymphoid tissues – Lymphocytes • Influences on Digestion and Absorption Psychological influences – • Chemical influences – • Taste, smell, and presentation of food Type of protein you eat and the way it is prepared Bacterial influences – Hydrochloric acid kills Nutrition and GI Disorders • • Constipation – Hard, dry, infrequent stools – Reduced by high fiber, fluid intake, exercise Diarrhea – Loose, watery, frequent stools – Symptom of diseases/infections – Can cause dehydration – Broth, tea, toast, and other low-fiber foods can help reduce Nutrition and GI Disorders • • Diverticulosis – Pouches along colon – High-fiber diet reduces formation Heartburn and GERD – Reduced by smaller meals, less fat – Smoking weakens the esophageal sphincter – Being overweight often worsens symptoms Nutrition and GI Disorders • Irritable bowel syndrome – Causes abdominal pain, diarrhea or constipation, and cramps – Stress and certain foods aggravate the symptoms – Can usually be controlled by diet and lifestyle modifications • Stress management Nutrition and GI Disorders • Colorectal cancer – • Gas – • Fiber-rich diet may reduce risk Most foods that contain carbohydrates can cause Ulcers – Pain in the upper abdomen – Can cause nausea, vomiting, loss of appetite, and weight loss Nutrition and GI Disorders • Functional dyspepsia – Chronic pain in the upper abdomen – Treat with medicine and stress reduction ... Taste and Smell: The Beginnings of Our Food Sight, smell, thought, taste, and sound Experience – Trigger a set of responses that prepare the digestive tract to receive food The Gastrointestinal... Digestion and Absorption • Esophagus – Transports food to stomach – Esophageal sphincter Putting it All Together: Digestion and Absorption • Stomach – Hydrochloric acid prepares protein for digestion... absorptive surface • Most nutrients absorbed here • Fat-soluble nutrients go into lymph • Other nutrients go into blood Putting it All Together: Digestion and Absorption • Large intestine – Sections