Eating and Human Digestion - NUTR 1100 Student Slides PDF

Eating and Human Digestion NUTR 1100 Stephanie Gladman, MHSc, RD Registered Dietitian  Learning Outcomes Recall the anatomy and function of the gastrointestinal tract, major structures and their role Describe nutrition-related physiological processes, e.g.,...

Eating and Human Digestion NUTR 1100 Stephanie Gladman, MHSc, RD Registered Dietitian  Learning Outcomes Recall the anatomy and function of the gastrointestinal tract, major structures and their role Describe nutrition-related physiological processes, e.g., digestion, absorption, transport, and elimination and their role to deliver and use energy and nutrients in the body. Differentiate between the different types of absorption (water and fat soluble), including which system is used and rationale. Describe metabolism processes and the role to use energy and nutrients in the body.  Digestion (Brightspace content: videos, links Read + view all content)  Digestive System – Where does food travel? Digestive System – Accessory Organs  Human Digestion The act of breaking down nutrients to their smallest parts The smallest parts of food are the nutrients: Carbohydrates into ___________ I’m not absorbing smarties and spaghetti Fats (lipids) into _____ _______ + ____________ noodles, I’m just eating them ! Proteins into _______ ________ I am absorbing some Vitamins monosaccharides ! Minerals Water This Photo by Unknown Author is licensed under CC BY-SA  Human Digestion Mechanical digestion: _____________ _________ down into smaller parts Mouth (teeth – chewing) Stomach (smooth muscles) Muscular contractions (peristalsis) Chemical digestion: _________________________ food – their chemical bonds Enzymes (speed up chemical breakdown) Acids (hydrochloric acid – gastric juice)  Digestive System Lumen = inside space of GI tract GI (gastrointestinal) 30 ft long hollow tube, lumen which is lined by mucosal cells GI tract supplies body with a constant supply of water and nutrients by Passage of food through the tract Mucosal cells Secretion of digestive juices and enzymes surround the Digestion of food lumen (open space) Absorption of water and nutrients Circulating blood to distribute the absorbed nutrients  Digestive System Each part of the digestive tract has specific functions Passage of food Temporary storage Digest food Absorb food Eliminate waste  Structure, Enzymes + Secretions Mouth Teeth Taste buds Saliva (1-1.5L produced/day Moistens Taste carried to taste buds Contains enzymes (salivary amylase the enzyme that break down starch) Protects teeth Forms a ________ Structure, Enzymes and Secretions Throat (pharynx) Trachea →lungs Esophagus → stomach Epiglottis: prevents food from going down the wrong tube Watch the swallowing video in D2L This Photo by Unknown Author is licensed under CC BY-NC-ND Pharynx Esophagus Connects pharynx to stomach Bolus of food is moved by rhythmic muscle contractions called ____________ Food passes through a muscular ring called a __________ at the end of the esophagus to enter the stomach No digestion takes place in the esophagus  Structures, Enzymes & Secretions Stomach Temporary storage until it can be processed https://www.refluxgate.com/sphincter-laryngopharyngeal- reflux-disease Mechanical digestion + chemical digestion Gastric glands produce gastric juice containing Water ___________: inactive form of protein-digesting enzyme pepsin _____________ _________: kills microorganisms, unfolds proteins, activates pepsinogen to pepsin, and inhibits amylase (enzyme that works on starch i.e. carbohydrates)  Structures, Enzymes & Secretions https://www.refluxgate.com/sphincter-laryngopharyngeal- Stomach reflux-disease __________ protects stomach lining from pepsin and hydrochloric acid __________ is a semi-liquid blend of foods and gastric secretions The chyme leaves the stomach to enter the small intestine through the ____________ _____________ Structures, Enzymes & Secretions Stomach emptying is regulated by chyme and signals from nerves and hormones like the brain, stomach, small intestine) affected by meal size large meal > small meal > liquid meal solids > liquids affected by meal composition fat > fibre and protein > carbohydrates and sugars ➔ affects satiety: importance of balanced meal  Structure, Enzymes + Secretions Small intestine is the main site of chemical digestion and absorption and has 3 parts as seen in the image This Photo by Unknown Author is licensed under CC BY-SA-NC  Structure, Enzymes + Secretions Accessory organs play a role: _________ makes: Bicarbonate Pancreatic amylase Protease Lipase _______ makes bile _________ stores the bile  Structure, Enzymes + Secretions Bile emulsifies lipids (fats) a type of mechanical digestion) It makes fat particles small enough so enzymes can break the bonds (chemical) Lipases (enzymes) can then break the bonds to release glycerol and fatty acids (chemical digestion) This Photo by Unknown Author is licensed under CC BY-SA-NC Structure, Enzymes + Secretions Large Intestine Things that are not absorbed end up here Some absorption happens… Water Vitamins (ex: vitamin K) Fibre takes action Prebiotics Probiotics This Photo by Unknown Author is licensed under CC BY Structure, Enzymes + Secretions Rectum Storage area Packs all the wastes and expels through anus Transit Time Amount of time from mouth to anus varies: Mouth to small intestine: 6-8 hours Mouth to large intestine: ~40 hours Transit Time Impacts on transit times: Diet composition – meat longer, fibre + water faster Physical activity level Emotional state Health status, diarrhea – very fast Use of laxatives The shorter the time, the healthier the intestinal wall The longer it take the more harmful bacteria are produced Absorption Absorption Most absorption happens in _________ ___________ Once food is digested into their smallest molecules (NUTRIENTS) they now must cross the gastrointestinal wall into the circulatory system Absorption There are folds, villi and microvilli in small intestine They are little finger-like projections each with access to the circulatory system, all to absorb the maximum number of nutrients that you eat  3 Methods of Absorption Passive / Simple diffusion Facilitated diffusion Active transport Passive diffusion Passive/Simple diffusion- Nutrients absorbed due to a concentration gradient When the concentration is greater in the GI tract than the inside of the intestinal wall, nutrient is forced to enter the cell membrane No energy is required Facilitated diffusion Facilitated diffusion- similar to passive diffusion, from a high concentration to low No energy is required However, requires a special protein carrier to carry nutrients across Active diffusion Nutrients are absorbed from a low concentration to a high concentration - Process requires energy and a carrier to shuttle nutrients across the cell membrane  Post Absorption Circulatory / cardiovascular system Urinary system Waste removal  Movement of Nutrients Post absorption, nutrients are delivered to the cells by the circulatory / cardiovascular system AND the lymph system Water soluble nutrients are delivered via the circulatory system GIT cells > capillaries in the villi > hepatic portal vein (bloodstream) > liver Fat soluble nutrients are delivered via the lymph system GIT cells > lymph system (also involved in immunity) Most fat and fat soluble vitamins cannot be absorbed directly into the blood because water + fat don't mix so they are packaged within protein vehicle – they are too big for capillaries - these fat packages go from the intestinal villi to the neck are and dumped into the blood (not filtered by the liver)  Circulatory / Cardiovascular System Transports nutrients to cells and waste away from cells Consists of: heart, blood and blood vessels Nutrients are absorbed in the small intestine and go to the liver by the hepatic portal vein. From the liver the blood goes to the heart by the inferior vena cava and then to the lungs to get oxygen and then goes to all body cels  Liver An incredibly complex organ : Collects nutrients absorbed in the digestive track Stores nutrients Converts nutrients into substances that the body can use. Filters blood and removes toxic substances and converts them into harmless substance to be removed from the body  Lymphatic system 1.Removes fluid from tissues and filters it before returning it to the blood 2. Very involved with immunity as well: contains immune cells to fight antigens 3.Transports & absorbs fat- soluble nutrients Waste Removal Removal of Waste Undigested/unabsorbed materials (feces): GI tract Metabolic wastes: 1. kidneys (primary site): filter water and small molecules out of blood, reabsorb what’s needed, excretes excess (urine) 2. lungs: CO2, water 3. skin (sweat): water, minerals, N-containing wastes  Excretion and Waste This Photo by Unknown Author is licensed under This Photo by Unknown Author is licensed under CC BY-NC-ND CC BY Review differences: Digestion Break down of food into its constituent, simple nutrients Absorption Nutrients enter the body by crossing the gastrointestinal wall and go into the circulatory system Metabolism What happens to the nutrients once inside the body Metabolism Once absorbed nutrients used for energy is called __________ __ When larger structures are built, this is known as __________ __ and this requires energy When larger structures are broken down, this is known as __________ __ and this creates energy  Digestive system summary Gastrointestin al tract Mouth Pharnyx Small Large Esophagus Stomach Rectum intestines intestines Saliva Peristalsis Food Most Absorb Stores lubricates Epiglottis starts storage water feces digestion & keeps absorption Amylase food from Acid kills Bacteria starts airways bacteria, Pancreatic digest starch unfolds enzymes fiber, digestion proteins, digest food make activates & vitamins Chewing pepsin bicarbonate breaks neutralizes down Produces acid food chyme Bile breaks fat Source: Sorensen, J., Langara College, & Nutrition and Food Service Management Program. (n.d.). The Digestive System. Retrieved from https://pressbooks.bccampus.ca/nutr1100/chapter/the-digestive-system-2/  Student Independent Activities Review Allergies and Intolerances section  Outcome Reviews Recalled the anatomy and function of the gastrointestinal tract, major structures and their role Described nutrition-related physiological processes, e.g., digestion, absorption, transport, and elimination and their role to deliver and use energy and nutrients in the body. Differentiated between the different types of absorption (water and fat soluble), including which system is used and rationale. Described metabolism processes and the role to use energy and nutrients in the body.  Participation Activity 1. Go to kahoot.it 2. Enter the PIN 3. Put your first name + last 3 digits of your ID