Digestive System Notes PDF

Official (Closed) - Non Sensitive Topic 4 Digestive System Marieb (2006) Fundamentals of Biology, PFP, LSCT, Ngee Ann...

Official (Closed) - Non Sensitive Topic 4 Digestive System Marieb (2006) Fundamentals of Biology, PFP, LSCT, Ngee Ann Polytechnic  Official (Closed) - Non Sensitive Terms Digest = Break down into smaller pieces Absorb = Deliver into the blood stream Enzyme = biological catalyst that speeds up reaction 2  Official (Closed) - Non Sensitive Learning objectives Outline the functions of various nutrients Identify the organs of the digestive system and relate them to their functions Distinguish between peristalsis and segmentation Describe the physical (mechanical) digestion of food Describe the chemical (enzymatic) digestion of food Outline the fate of various foods we eat in terms of their digestion, absorption and utilization 3  Official (Closed) - Non Sensitive Functions of the digestive system Ingest (take in) food Digest (break down) food into smaller pieces. Mechanical (physical) Enzymatic (chemical) Absorb and provide nutrients to the body cells Eliminate waste 4  Official (Closed) - Non Sensitive Nutrients Carbohydrates Proteins Lipids Vitamins Ions/Minerals/Electrolytes (e.g. Na, K, Ca, P, Mg) Water 5  Official (Closed) - Non Sensitive Carbohydrates (elements C, H, O) Depending on number of subunits (n) Monosaccharides Disaccharides Oligosaccharides (n =3 to 10) Polysaccharides 6  Official (Closed) - Non Sensitive Monosaccharides Small enough to be absorbed directly into blood Common monosaccharides (6C) Glucose (Source of ATP) Fructose (Found in fruits, soft drinks) Galactose (Found in milk) 7  Official (Closed) - Non Sensitive Disaccharides Made up of _____ monosaccharide subunits Digested by enzymes into monosaccharide before absorption into the blood Common Disaccharides Sucrose (table sugar) = glucose + fructose Maltose = glucose + glucose Lactose (milk sugar) = glucose + galactose Maltose by Chelsey. Fresh Milk © Table sugar by Tim Ster CC BY 3.0 Oneida County Tourism CC BY-SA 2.5 8  Official (Closed) - Non Sensitive Polysaccharides Many monosaccharides (e.g. glucose) joined together by glycosidic bonds Digested into ___________before absorption Major polysaccharides Starch from plants Main source in our diet Digested into glucose Glycogen from animals Not an important source in our diet. Cellulose from plants Indigestible Provides fibre in our diet Chitin cell wall of fungi 9  Official (Closed) - Non Sensitive Proteins Made up of elements C, H, N, O, S Long chains of amino acids joined by peptide bonds 20 common amino acids Essential; must be supplied in diet Non-essential; our body can make them Many types of proteins possible 10  Official (Closed) - Non Sensitive https://www.scienceabc.com/pure-sciences/what-are-the-two-rare-amino-acids.html  Official (Closed) - Non Sensitive Proteins have many diverse functions 1. Enzymes (speed up reactions; e.g. amylase, pepsin, proteases, lipases) 2. Muscle contraction, e.g. actin and myosin 3. Hormones, e.g. insulin, parathyroid hormone, growth hormone 4. Hemoglobin (for oxygen transport) 5. Antibodies (for immune defense) 6. Ion channels, carriers and pumps 7. Membrane receptors 8. Energy source (after glucose/glycogen and fats are exhausted) 12  Official (Closed) - Non Sensitive What are enzymes? Enzymes are biological protein catalysts that speed up reactions. One characteristic of enzymes is that they recognise specific molecules. For example, the amylase in our saliva recognizes and breaks down only starch. 13  Official (Closed) - Non Sensitive Lipids Triglycerides (“fats”) Made of glycerol + 3 fatty acids Digested by lipases Fatty acids Saturated Unsaturated Cholesterol Phospholipids Made of glycerol + 2 fatty acids + 1 phosphate group e.g. lecithin found in egg yolk and soya bean 14  Official (Closed) - Non Sensitive Functions of lipids Lipid Uses in the body Triglycerides and fatty Source of energy (ATP) acids (e.g. during overnight fasting) Adipose tissues Cushion and protect internal organs Insulate body Store energy Phospholipids Forms bilayer of cell membrane Cholesterol Component of cell membranes Precursor for synthesis of steroid hormones e.g. sex hormones Component of bile salts which emulsify fats to aid in their digestion and absorption. 15  Official (Closed) - Non Sensitive Vitamins Organic chemicals needed in small quantities but essential for life Vitamin Functions A Vision B Coenzymes for enzymes complex C Antioxidant, collagen synthesis, etc D Absorption of calcium in intestines E Antioxidant 16  Official (Closed) - Non Minerals (Ions, Sensitive electrolytes) Mineral Functions Calcium (Ca) Strong bone and teeth; muscle and nerve functions; blood clotting Sodium (Na) Osmoregulation; nerve and muscle functions Potassium (K) Nerve and muscle functions Iron (Fe) Component of hemoglobin; components of enzymes Phosphorous (P) Component of ATP, nucleic acids, phospholipids, cell membranes 17  Official (Closed) - Non Sensitive Water Medium for all biochemical reactions Transport of solutes Maintain body heat 18  Official (Closed) - Non Sensitive Organs of the digestive system 19  Official (Closed) - Non Sensitive Digestive tract (“hollow Accessory organs tube”) Teeth Mouth Salivary glands Throat (Pharynx) Pancreas Esophagus Liver Stomach Gall bladder Small intestine Large intestine (colon) Lumen of entire digestive tract is lined Anus with various epithelial tissues for protective, secretive or absorptive functions https://www.kcvl.cz/en/atlas.aspx?nID=100 20  Official (Closed) - Non Sensitive Mouth (oral cavity) Saliva secreted by salivary glands Moistens food Lubricates mouth Saliva contains lysozyme (antibacterial) and salivary amylase which digests starch Teeth cut, tear, crush and grind food which physically break down food into smaller particles 21  Official (Closed) - Non Sensitive Throat (Pharynx) Common gateway to the entrance of trachea and esophagus When we swallow food and drink, epiglottis closes the opening of the trachea so food and drink enter the esophagus instead of trachea http://www.drugs.com/health-guide/images/205051.jpg 22  Official (Closed) - Non Sensitive Esophagus Muscular tube carrying food from throat to stomach Behind the trachea Once swallowed, food is propelled down esophagus into stomach within seconds by strong smooth muscular contractions (peristalsis) Marieb (2006) 23  Official (Closed) - Non Sensitive Stomach Muscular bag that can expand to 20x its original size Holds up to 2 L of food and gastric juice Muscular stomach wall mixes and churn food with acidic gastric juice Stomach lining contains gastric glands which secrete gastric juice Protein digestion begins here Pyloric sphincter acts like a valve to release small amounts of stomach content into small intestine Marieb (2006) 24  Official (Closed) - Non Sensitive Gastric Juice Components Marieb (2006) Gastric Secreted by: Functions secretions Mucous Mucous neck cells Coats and protects stomach lining from digestion by pepsin HCl Parietal cells Convert pepsinogen to pepsin Inhibits salivary amylase Inhibits bacteria Pepsinogen Chief cells Precursor of pepsin. Pepsin digests proteins Hormones Endocrine cells Gastrin controls gastric juice (E.g. Gastrin) secretion. Excessive secretion of gastric juice causes gastric ulcers because the corrosive action of HCl (pH1-2) eats into the stomach wall. 25  Official (Closed) - Non Sensitive Small intestine Major site for digestion and absorption About 6 m long 3 sections Duodenum (25 cm) Jejunum (2.5 m) Ileum (3.5 m) Marieb (2006) 26  Official (Closed) - Non Sensitive Small intestine is highly adapted for absorption Increased surface area for absorption 1. Wall forms circular folds 2. Villi, finger-like projections from Small intestine https://www.kcvl.cz/en/atlas.aspx?nID=100 the circular folds 3. S.I. epithelial cells possess microvilli Blood capillaries and lacteals run through the villi Capillaries transport amino acids and glucose to the liver Lacteal transports lipids to the lymphatic circulation https://www2.indstate.edu/ Villi [Online image]. thcme/mmmoga/histology/ slide69.html 27  Official (Closed) - Non Sensitive Where are the circular folds, villi, microvilli, lacteal and blood capillaries? Marieb (2006) 28  Official (Closed) - Non Segmentation in small Sensitive intestine Mix food back and forth Distribute food throughout the S.I. to ensure good absorption Marieb (2006). 29  Official (Closed) - Non Sensitive Large intestine 1.5 m long Caecum Appendix attached to the caecum Colon Rectum Anus (opening) Functions Absorbs remaining water, minerals and vitamins Eliminates indigestible food as faeces Many resident bacteria here Colon E. coli in colon provides host with vitamin https://www.nursingtimes.net/clinical-archive/gastroenterology/ K in return for nutrients and shelter gastrointestinal-tract-5-anatomy-functions-large-intestine-23-09- 2019/ Resident bacteria prevent harmful ones from colonizing 30  Official (Closed) - Non Sensitive Accessory organs of the digestive system 31  Official (Closed) - Non Sensitive Pancreas Behind stomach Secretes alkaline pancreatic juice into S.I; Juice contains Amylases  digest _____ Proteases  digest ______ Lipases  digest _________ Bicarbonate (HCO3-) ion  neutralize HCl Secrete hormones insulin and glucagon which regulate blood glucose levels Marieb (2006) Insulin lowers blood glucose Glucagon raises blood glucose 32  Official (Closed) - Non Sensitive Liver Located on the right side of the body under the diaphragm Connected to the gall bladder Absorbed monosaccharides and amino acids are transported from the small intestine to liver before delivery to rest of body Many functions: Produce bile which emulsifies fat Detoxify drugs and toxins Store excess glucose as Marieb (2006) glycogen 33  Official (Closed) - Non Sensitive Gall bladder Stores bile produced by liver Bile is secreted into duodenum via bile duct Bile aids in mechanical digestion of fats (emulsification) Marieb (2006) 34  Official (Closed) - Non Sensitive Food digestion and absorption 35  Official (Closed) - Non Sensitive Digestion: Breaking down large molecules into smaller molecules Physical Chemical Chewing HCl Mixing and Amylases, churning disaccharidases Segmentation Proteases, Emulsification of peptidases fats Lipases 36  Official (Closed) - Non Sensitive Identify the major nutrients in the following food: https://www.smallstarter.com/ https://aromacookery.com/2010/05/25/chef-han-chicken-rice/https://www.clipartkey.com/search/glass-of-milk/ browse-ideas/bread-bakery- business/ 37  Official (Closed) - Non Sensitive Mouth Digestion begins in mouth Teeth cut, tear and grind food into smaller pieces Salivary gland secretes salivary amylase Salivary glands Salivary amylase Starch Oligosacchari + Maltose Mouth des (Dextrins) 38  Official (Closed) - Non Sensitive Stomach Mixing and churning break down food Salivary amylase inhibited by HCl Protein digestion begins Chief cells Pepsinogen Pariet (inactive) al HCl cells Pepsin Proteins Shorter proteins Stomach (polypeptides) 39  Official (Closed) - Non Sensitive Small intestine Segmentation breaks up food and spreads food All 3 classes of food are digested here Pancreatic amylase, proteases, lipases in pancreatic juice Bile secretion from gall bladder/ liver Disaccharidases attached to the microvilli (brush border ) of SI epithelium Peptidases inside the SI epithelial cells 40  Official (Closed) - Non Sensitive Small intestine-Carbohydrate digestion Note: Strategic location of sucrase, maltase and lactase at microvilli 41  Official (Closed) - Non Small intestine -Protein Digestion & Sensitive Absorption Protein digestion continues and is completed here; pepsin inhibited by alkaline pancreatic juice Pepsin Polypeptides Stomach Protein Pancreatic s proteases SI Lumen (trypsin, chymotrypsin, carboxypeptida hepatic portal vein to liver Amino acids, tripeptides, se) Blood capillary dipeptides Peptidases Microvilli Absorption Amino acids 42  Official (Closed) - Non Sensitive Small Intestine: Fat digestion H20 H20 Large aggregate of triglycerides S.I. Lumen + Emulsification H20 H20 Triglycerides Bile salts Emulsified triglycerides hydrophobic Amphipathic (micelles) Pancreati c lipase Fatty acids Monoglycerides 43  Official (Closed) - Non Small intestine -Fat is absorbed into Sensitive lacteals In villi Van Putte, Regan & Russo (2010) 44  Official (Closed) - Non Sensitive Large intestine No digestion Remaining water, minerals and vitamins absorbed Semi-solid indigestible material eliminated as feces 45  Official (Closed) - Non Sensitive Key Concepts Mechanical and enzymatic processes digest food into smaller particles that can be readily absorbed Because enzymes are specific, a variety of enzymes are required in the chemical digestion of carbohydrates, proteins and lipids Monosaccharides and amino acids are absorbed into blood capillary and then delivered to liver Lipids are absorbed into the lacteal and enter the lymphatic system 46  Official (Closed) - Non Sensitive Summary of CHO digestion Enzyme Produced Site of Substrate Product by action Salivary Salivary Mouth Starch Maltose, amylase glands dextrins Pancreatic Pancreas Lumen of Starch, Maltose, amylase small dextrins glucose intestine Disacharridas Microvilli Brush Maltose, es (maltase, (Brush border of Sucrose, sucrose, border) of small Lactose lactase) small intestine intestine 47  Official (Closed) - Non Sensitive Summary of protein digestion Enzyme Produced by Site of Substrate Product action Pepsin Stomach Proteins Shorter proteins (Peptides) Pancreati Pancreas Lumen of Proteins Tri- c small Peptides, protease intestine di-peptides, s amino acids Peptidas Microvilli Brush Tri- and di- Amino es (Brush border) border of Peptides acids of small small intestine intestine 48  Official (Closed) - Non Sensitive References Chelsey. Maltose. Contributions to https://cornellbiochem.wikispaces.com/ are licensed under a Creative Commons Attribution 3.0 License. Claybrook, T. Flexible Endoscopic Evaluation of Swallowing 2 [Video file]. Retrieved from https://www.youtube.com/watch?v=DB_E2BygPJk Colon [Online image]. Retrieved from http://indalohealth.com/wp-content/uploads/2010/06/colonic_irrigation_diagram_colon_large.gif Fatty acids [Online image]. Retrieved from https://figures.boundless-cdn.com/18562/large/figure-03-03-05.jpeg Forward, D. Through the Esophagus The Function of Peristalsis [Video file]. Retrieved from https://www.youtube.com/watch?v=rJS-Kh5wCQU Marieb, E.N. (2006). Essentials of Human Anatomy and Physiology, (8th ed). Pearson. McAnimation: Organs of Digestion [Video file]. Retrieved from http://highered.mheducation.com/sites/0072495855/student_view0/chapter26/animation__organs_of_dige stion.html Oneida County Tourism (June 24, 2011). Fresh milk. All rights reserved Small intestine [Online image]. Retrieved from http://www.kcvl.cz/atlas/278.jpg Tim Ster (2016, June 8). Table sugar. CC BY-SA 2.5 Van Putte, C., Regan, J. & Russo, A. (2010). Seeley's Essentials of Anatomy and Physiology (7th Ed). McGraw-Hill. Villi [Online image]. Retrieved from 49