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  • Figure 3-2 The Colon The colon begins with the ascending colon rising upward toward the liver. It becomes the transverse colon as it turns and crosses the body toward the spleen. The descending colon turns downward and becomes the sigmoid colon, which extends to the rectum. Along the way, the colon mixes the intestinal contents, absorbs water and salts, and forms stools.
  • Figure 3.2: The Colon. The colon begins with the ascending colon rising upward toward the liver. It becomes the transverse colon as it turns and crosses the body toward the spleen. The descending colon turns downward and becomes the sigmoid colon, which extends to the rectum. Along the way, the colon mixes the intestinal contents, absorbs water and salts, and forms stools.
  • Figure 3-8 A bsorption of Nutrients Absorption of nutrients into intestinal cells typically occurs by simple diffusion, facilitated diffusion, or active transport. Occasionally, a large molecule is absorbed by endocytosis — a process in which the cell membrane engulfs the molecule, forming a sac that separates from the membrane and moves into the cell.
  • Figure 3.9: Absorption of Nutrients. Absorption of nutrients into intestinal cells typically occurs by simple diffusion, facilitated diffusion, or active transport. Occasionally, a large molecule is absorbed by endocytosis — a process in which the cell membrane engulfs the molecule, forming a sac that separates from the membrane and moves into the cell.

Chapter32012 Chapter32012 Presentation Transcript

  • Digestion,Digestion, Absorption, andAbsorption, and TransportTransport Chapter 3Chapter 3
  • DigestionDigestion • Breaking down foods into nutrients • Prepare for absorption • Challenges of digestion • Tasks of the mouth • Diaphragm • Steady movement • Lubrication of food • Digestive enzyme functions • Excretion of waste
  • Anatomy of the Digestive TractAnatomy of the Digestive Tract • Gastrointestinal (GI) tract • Flexible and muscular • Path • Mouth → esophagus → stomach → small intestine → large intestine → rectum → anus • Lumen • Continuous
  • The Gastrointestinal TractThe Gastrointestinal Tract
  • Anatomy of the Digestive TractAnatomy of the Digestive Tract • Mouth • Process of digestion begins • Mastication • Four basic taste sensations • Savory • Aroma, texture, and temperature • Pharynx • Bolus
  • Anatomy of the Digestive TractAnatomy of the Digestive Tract • Esophagus • Two sphincters • Upper esophageal sphincter • Lower esophageal sphincter • Stomach • Movement of bolus • Chyme • Pyloric sphincter
  • Anatomy of the Digestive TractAnatomy of the Digestive Tract • Small intestine • Common bile duct • Pancreas and gall bladder • Three segments • Large intestine (colon) • Ileocecal valve • Withdrawal of water • Rectum and anus
  • Transverse colon Ascending colon Descending colon Sigmoid colonAnus Rectum Appendix Opening from small intestine to large intestine End of small intestine Stepped Art Figure 3-2 p72
  • Transverse colon Ascending colon Descending colon Sigmoid colonAnus Rectum Appendix Opening from small intestine to large intestine End of small intestine Stepped Art Fig. 3-2, p. 72
  • Muscular Action of DigestionMuscular Action of Digestion • Peristalsis • Circular and longitudinal muscles working together • Rate and intensity of contractions vary • Factors that may interfere with peristalsis • Stomach action • Circular, longitudinal, and diagonal muscles • Timing the release of chyme
  • Stomach MusclesStomach Muscles
  • Muscular Action of DigestionMuscular Action of Digestion • Segmentation • Contraction of circular muscles in small intestine • Mix chyme • Promote contact with absorption cells • Sphincter contractions • Periodically open and close • Control pace of GI tract contents
  • An Example of a SphincterAn Example of a Sphincter MuscleMuscle
  • Secretions of DigestionSecretions of Digestion • Five organs • Salivary glands, stomach, pancreas, liver, small intestine • Secretions • Water • Enzymes • Protein facilitator of chemical reactions • Hydrolysis
  • Secretions of DigestionSecretions of Digestion • Saliva • Moisten food for easy passage • Protective role • Carbohydrate digestion • Gastric juice • Protein digestion • Mucus • pH units
  • The Salivary Glands
  • Secretions of DigestionSecretions of Digestion • Pancreatic juice and intestinal enzymes • Released via ducts into duodenum • Enzymes act on all three energy nutrients • Sodium bicarbonate • Bile • Liver • Gallbladder
  • Summary of Digestive Secretions & Their Major Actions
  • The Final StageThe Final Stage • Undigested residues • Exercise intestinal muscles • Retention of water • Colon • Intestinal bacteria • Recyclable materials • Water and dissolved salts
  • AbsorptionAbsorption • Small intestine • Majority of absorption • Ten feet long • Surface area • Absorption techniques • Simple diffusion • Facilitated diffusion • Active transport
  • Carrier loads nutrient on outside of cell . . . Carrier loads nutrient on outside of cell . . . Outside cell Cell membrane . . . and then releases it on inside of cell. . . . and then releases it on inside of cell. Inside cell FACILITATED DIFFUSION Some nutrients (such as the water- soluble vitamins) are absorbed by facilitated diffusion. They need a specific carrier to transport them from one side of the cell membrane to the other. (Alternatively, facilitated diffusion may occur when the carrier changes the cell membrane in such a way that the nutrients can pass through.) ACTIVE TRANSPORT Some nutrients (such as glucose and amino acids) must be absorbed actively. These nutrients move against a concentration gradient, which requires energy. Stepped Art Some nutrients (such as water and small lipids) are absorbed by simple diffusion. They cross into intestinal cells freely. SIMPLE DIFFUSION Figure 3-8 p77
  • Carrier loads nutrient on outside of cell . . . Carrier loads nutrient on outside of cell . . . Outside cell Cell membrane . . . and then releases it on inside of cell. . . . and then releases it on inside of cell. Inside cell FACILITATED DIFFUSION Some nutrients (such as the water- soluble vitamins) are absorbed by facilitated diffusion. They need a specific carrier to transport them from one side of the cell membrane to the other. (Alternatively, facilitated diffusion may occur when the carrier changes the cell membrane in such a way that the nutrients can pass through.) ACTIVE TRANSPORT Some nutrients (such as glucose and amino acids) must be absorbed actively. These nutrients move against a concentration gradient, which requires energy. Stepped Art Some nutrients (such as water and small lipids) are absorbed by simple diffusion. They cross into intestinal cells freely. SIMPLE DIFFUSION Fig. 3-9, p. 78
  • Anatomy of the AbsorptiveAnatomy of the Absorptive SystemSystem • Villi • Select and regulate nutrients absorbed • Microvilli • Enzymes and “pumps” • Crypts • Secretion of intestinal juices • Goblet cells • Mucus secretion
  • A Closer Look at the IntestinalA Closer Look at the Intestinal CellsCells • Villi cells • Regulate nutrient absorption based on needs • Microvilli • Enzymes and ‘pumps’ • Specialized cells • Food combining • Enhanced use in the body
  • A Closer Look at the Intestinal Cells • Transport pathways • Bloodstream • Water-soluble nutrients and smaller products of fat digestion • Liver • Lymphatic system • Larger fats and fat-soluble vitamins • Chylomicrons • Bypass liver at first
  • The Vascular SystemThe Vascular System • Closed system of vessels • Heart pump • Blood • Delivers oxygen and nutrients • Removes carbon dioxide and wastes • Blood flow • Special routing for digestive system • Liver
  • The Vascular SystemThe Vascular System
  • The LiverThe Liver
  • The Lymphatic SystemThe Lymphatic System • One-way route • No pump • Circulation between cells • Entry into bloodstream • Subclavian vein • Nutrients in lymphatic vessels • Bypass liver at first
  • Health and Regulation of the GIHealth and Regulation of the GI TractTract • Gastrointestinal bacteria – flora • Most are not harmful • Benefits of gastrointestinal bacteria • Factors influencing bacteria presence • Diet – probiotics • Prebiotics • Others • Digestion of fibers and complex proteins • Vitamin production
  • Gastrointestinal Hormones andGastrointestinal Hormones and Nerve PathwaysNerve Pathways • Homeostatic regulation • Endocrine system • Nervous system • Feedback mechanisms • Examples • GI hormones • Gastrin • Secretin • Cholecystokinin (CCK)
  • An Example of a NegativeAn Example of a Negative Feedback LoopFeedback Loop
  • The Primary actions ofThe Primary actions of Selected GI HormonesSelected GI Hormones
  • The System at Its BestThe System at Its Best • Sensitive and responsive to environment • Immunity against intestinal diseases • Defense against foreign invaders • Health of digestive system • Healthy supply of blood • Lifestyle factors • Types of foods eaten • Balance, moderation, adequacy, and variety
  • Common DigestiveCommon Digestive ProblemsProblems Highlight 3Highlight 3
  • ChokingChoking • Food slips into trachea • Cuts off breathing • International sign for choking • Heimlich maneuver • Foods commonly associated with choking • Prevention of choking
  • Normal Swallowing andNormal Swallowing and ChokingChoking
  • First Aid for ChokingFirst Aid for Choking
  • VomitingVomiting • Vomiting • Adaptive mechanism of the body • Medical treatment • Dehydration • Self induced
  • Diarrhea • Diarrhea • Symptom of medical conditions & treatments • Irritable bowel syndrome (IBS) • Colitis • Treatment
  • Irritable Bowel Syndrome and Colitis • Irritable bowel syndrome • Characterization • Cause • Unknown • Triggers • Colitis • Inflammation of large intestine
  • Celiac Disease • Autoimmune disease • Inflammation of small intestine • Gluten-containing foods • Symptoms • Treatment • Rehydration
  • ConstipationConstipation • Not a disease • Symptoms of constipation • Causes • Lifestyle • Side effect of medications • Prevention • Fiber and water • Physical activity
  • Constipation • Hemorrhoids • Diverticulosis • Laxatives • Harmful practices • Colonic irrigation
  • Belching and GasBelching and Gas • Belching • Swallowed air • Prevention • Intestinal gas • Consumption of certain foods • Individually determined
  • Heartburn andHeartburn and “Acid“Acid Indigestion”Indigestion” • Gastroesophageal reflux (heartburn) • Causes • Prevention • Indigestion • Causes • Antacids and acid controllers • Damage to esophagus • Barrett’s esophagus
  • Gastroesophageal Reflux
  • UlcersUlcers • Peptic ulcers • Gastric ulcers • Duodenal ulcers • Causes • Bacterial infection • Anti-inflammatory drugs • Excessive gastric acid secretion • Ulcer treatment regimen
  • Strategies to Prevent or Alleviate Common GI Problems