Digestion Absorption and Transport Chapter 3 Digestion 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 Tract Gastrointestinal GI tract Flexible and muscular Path Mouth esophagus stomach small intestine large intestine rectum anus Lumen Continuous space within the GI tract The Gastrointestinal Tract Anatomy of the Digestive Tract Mouth Process of digestion begins Once food is broken down Four basic taste sensations Sour Sweet Bitter Salty Umami Savory not sweet Pharynx directs food towards esophagus Food changes to bolus Anatomy of the Digestive Tract Esophagus Two sphincters Upper esophageal sphincter prevents food to come back up Lower esophageal sphincter releases it into stomach Stomach Movement of bolus Chyme Pyloric sphincter sends to small intenstine Anatomy of the Digestive Tract Small intestine Three segments Duodenum Jejunum Ileum Large intestine colon Ileocecal valve connect small intestine to large intestine colon The Colon Stomach Muscles Muscular Action of Digestion Peristalsis Segmentation Sphincter contractions Periodically open and close Control pace of GI tract contents An Example of a Sphincter Muscle Secretions of Digestion Salivary glands stomach pancreas liver Five organs small intestine Secretions Water Enzymes Secretions of Digestion Saliva comes from salivary glands Protects teeth lining of mouth Starts digestion of carbs Gastric juice comes from stomach Mixture of water enzymes and hydrochloric acid Used for protein digestion The pH Scale Secretions of Digestion Pancreatic juice and intestinal enzymes Released via ducts into duodenum Enzymes act on all three energy nutrients Sodium bicarbonate helps neutralize the acid Bile emulsifier Made in Liver Stored in Gallbladder Summary of Digestive Secretions Their Major Actions The Final Stage Colon Intestinal bacteria Recyclable materials Water and dissolved salts Absorption Small intestine Majority of absorption Ten feet long 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 Inside cell SIMPLE DIFFUSION FACILITATED DIFFUSION ACTIVE TRANSPORT and then releases it on inside of cell and then releases it on inside of cell Some nutrients such as water and small lipids are absorbed by simple diffusion They cross into intestinal cells freely 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 Some nutrients such as glucose and amino acids must be absorbed actively These nutrients move against a concentration gradient which requires energy Stepped Art Fig 3 9 p 78 Anatomy of the Absorptive System Villi inside of small intestine Select and regulate nutrients absorbed Microvilli on villi suck in nutrients Enzymes and pumps Crypts Secretion of intestinal juices Goblet cells on villi Mucus secretion A Closer Look at the Intestinal Cells Villi cells Regulate nutrient absorption based on needs Microvilli Specialized cells Food combining myth Enhanced use in the body A Closer Look at the Intestinal Cells Transport pathways Bloodstream Water soluble nutrients and smaller products of fat digestion Lymphatic system fats The 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 routes out toxins The Vascular System The Liver The 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 GI Tract Gastrointestinal bacteria flora Most are not harmful Benefits of gastrointestinal bacteria Factors influencing bacteria presence Probiotics found in fermented food Examples pickles sour kraut miso tofu Prebiotics components found in food Not digested Found in bacteria Gastrointestinal Hormones and Nerve Pathways Homeostatic regulation Endocrine system hormones are released Nervous system Feedback mechanisms Examples Getting cold getting goose bumps An Example of a Negative Feedback Loop The Primary actions of Selected GI Hormones Common Digestive Problems Highlight 3 Diarrhea Diarrhea Symptom of medical conditions treatments Irritable bowel syndrome IBS Women are 30x more likely to have than men Diarrhea and Constipation Treatment lifestyle diet Irritable Bowel Syndrome and Colitis Irritable bowel syndrome Characterization Constipation diarrhea bloating Cause Unknown Triggers Colitis Inflammation of large intestine Celiac Disease Autoimmune disease your body cannot digest protein found in wheat gluten Causes malnutrition stunted growth osteoporosis Constipation joint pain fatigue hair loss memory loss Non Celiac Sensitivity aren t tests Diet would still be the same Treatment cannot eat gluten ever Constipation Not a disease Causes Slow moving digestion lack of fiber lack of fluid lack of exercise Prevention drink more water exercise eat more fiber Gas Intestinal gas Consumption of certain foods Individually determined Heartburn and Acid Indigestion Gastroesophageal reflux heartburn Causes Esophageal sphincters don t close up properly Prevention Strategies to Prevent or Alleviate Common GI Problems
View Full Document
Unlocking...