FOS 2001 Man's Food: Lesson 4 - Digestion and Absorption of Chemicals in the Human Body
FOS 2001 Man's Food: Lesson 4 - Digestion and Absorption of Chemicals in the Human Body Fos 2001
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This 9 page Class Notes was uploaded by Sarah Sherr on Friday January 22, 2016. The Class Notes belongs to Fos 2001 at University of Florida taught by Agata Olga Kowalewska in Summer 2015. Since its upload, it has received 28 views. For similar materials see Man's Food in Nutrition and Food Sciences at University of Florida.
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Date Created: 01/22/16
Lesson 4: Digestion and Absorption of Chemicals in the Human Body Digestive System Terminology Define peristalsis and gastrin. Peristalsis – The forward, rhythmic motion that moves food through the digestive system. Gastrin – A digestive hormone produced in the stomach that stimulates digestive activities and increases motility and emptying. What are the four accessory organs in the digestive system? Salivary Glands Liver Gallbladder Pancreas Digestion and Absorption What is digestion? Digestion is the breaking down of macronutrients contained in foods into basic building blocks, or elements, required for the body’s nourishment. Even though fiber is nondigestible it offers what advantage in the digestive tract? Prevents/minimizes the risk of diverticular disease. Digestion and Absorption Link Define absorption. The movement of nutrients, salts, and water across the GI epithelium into blood or lymph. Know each of the components of the three most abundant dietary disaccharides: sucrose, lactose, and maltose. Sucrose = Glucose/Fructose Lactose = Glucose/Galactose Maltose = Glucose Starch is digested to glucose. What are proteins digested into? Peptide fragments and amino acids. What does most dietary fat consist of? Triglycerides Triglycerides are digested to monoglycerides and fatty acids. How are polar and nonpolar substances absorbed in digestion? Polar are absorbed via carriermediated transport. Nonpolar are absorbed across the intestinal epithelium by simple diffusion. Plant starch and Glycogen are the most abundant dietary carbohydrates. Where and how does the digestion of starch occur? It occurs in the mouth with the usage of salivary amylase. Where and how does the digestion of protein occur? It occurs in the stomach with the usage of pepsin. Which enzyme is maximally active at an acidic pH? Pepsin. Define a peptide. A chain of amino acids linked by peptide bonds. What organ provides the enzymes for digestion? Pancreas Where does most of the digestion and absorption occur in the G.I. tract? Small Intestine Humans lack digestive enzymes for what type(s) of carbohydrates? Cellulose (Plant polysaccharide) What does fiber do for humans in the digestive tract? Increases bulk of the stool and promotes its timely movement through the colon. By which two ways can salt and water be absorbed in the small intestine? Transcellular transport (intestinal epithelial cells) Paracellular transport (tight junctions) Describe transcellular transport. Active transport of sodium (ion channels/gradients/transports) – osmostic pressure The bacteria in the large intestine are responsible for synthesizing what vitamins? Some B complex vitamins and vitamin K. What is vitamin K’s function? Essential for liver synthesis of some blood clotting proteins. The Digestive System Know the fourteen components of the digestive system. Salivary Glands Oral Cavity Tongue Esophagus Stomach Liver Gallbladder Bile Duct Pancreas Pancreas Duct Large Intestine (colon) Small Intestine Rectum Anus The Digestive System and Nutrition Link What is the role of saliva? Moisten food and make chewing easier. Begin the chemical breakdown of carbohydrates in the food so that the stomach can continue converting the food into fuel for the body. What are the three glands that produce saliva? Parotid Submandular Sublingual What causes the epiglottis to cover the larynx to prevent your food from going down the wrong pipe? Gag reflexes What is another word for gum? Gingival How does the esophagus move the bolus toward the stomach? Gravity and muscle contractions (peristalsis) The cardiac sphincter connects the esophagus to the stomach and prevents food from backing up into the esophagus. What is the function of fundus? “Holds” the food and doses it with enzymes. Chime is sent through the one way exit of the stomach, Pyloric Sphincter, and into the small intestine. Name the three sections of the small intestine in order. DuodenumJejunumIleum Describe the action/function that occurs in each of the sections of the small intestine. Duodenum – Alkaline solution administered to neutralize stomach acids Jejunum – absorbs nutrients Ileum – Completes digestion, absorption of B12 and salts, and dumps to large intestine. Give a brief description on the functions of the liver, the gallbladder, and the pancreas in digestion. Liver – Produces enzymes for digestion, processes nutrients, removes toxins, and produces bile. Gallbladder – Releases bile Pancreas – Produces amylase for starch, Lipase for fat, Proteinase (protease) for protein The three functions of the large intestines: 1. Bacteria within the colon make and secrete vitamins necessary for your metabolism 2. Stores undigested and dead materials until they can be eliminated 3. Vitamins, minerals, and water are absorbed through walls of large intestine. The three components of the large intestine are Cecum, Colon, and Rectum. What is the cause of aphthous ulcers or canker sores? Faulty immune system or a nutritional defect What does it mean to have a lip or palate that is cleft? There was not enough tissue for the upper lip/jaw bone to fuse or for the root of the mouth to fully close. What are the symptoms of GERD? Inflammation Large production of stomach acid Cardiac Sphincter not working correctly Define hiatal hernia. A protrusion of the stomach through the diaphragm and up into the thoracic cavity. Where is peptic ulcer disease located? Lower esophagus Stomach Duodenum How can hepatitis be transmitted? Sexually Contaminated food Exposure to contaminated blood Define Crohn’s disease and list the symptoms. It is an inflammatory bowel disease that affects the colon and ileum by making them swell, causing severe pains, and diarrhea. Symptoms o Abdominal pain o Rectal bleeding o Arthritis When is TPN used? When a patient is unable to eat. Known all five of the common pathologies. Pathology Definition of Condition Treatment Explanation of Treatment Choledocholithiasis Presence of gallstones Choledocholithotripsy Crushing a gallstone in the common bile duct Diverticulitis Inflammation of the Diverticulectomy Surgical removal of a diverticula, caused when diverticulum food is trapped within the diverticula Anal fistula An abnormal tubelike Fistulectomy Removal of a fistula opening from the anus to the rectum; most begin as anal abscesses Hemorrhoids Varicose veins in the Hemorrhoidectomy Removal of a hemorrhoid rectum from the anorectal area Cholecystitis Inflammation of the Laparoscopic Surgical removal of the gallbladder; may be Cholecystectomy gallbladder with a caused by gallstones laparoscope Chemical Process of Digestion – The Beginning How is digestion stimulated by the brain? Sight, smell, and thought triggers secretion of various juices and hormones. What is the primary area of the brain responsible for regulating the cephalic phase of digestion? Medula Oblongata Which enzyme is responsible for the breakdown of starch in the mouth? Salivary Amylase Define bolus. A soft mass made up of a mixture of chewed food and saliva. The Esophagus and Beyond What are the two types of muscles that make up the esophagus and how do these muscles assist in the movement of the bolus to the abdominal cavity? Inner Circular Muscles – Constrict to make sure the bolus does not move backwards. Outer Longitudinal Muscles – Push forward and help break down the bolus. The Stomach What action gave rise to the term acid reflux? The cardiac sphincter allows the food to enter the stomach. If this valve does not shut completely, you get acid from the stomach moving back into the esophagus or gastric gases moving back into the esophagus; this is called “reflux.” Because the stomach is very low in pH, reflux causes irritation, burning, and inflammation of the esophagus, and that is where we get the term acid reflux, or heartburn. What is the major purpose of the stomach? A grinding organ that reduces the bolus into a very fine, liquefied material to increase its surface area. How is the stomach unique? Made of three types of muscular structure: Inner structure has a diagonal type of muscle Intermediate (middle) muscle layer is a circular type of muscle Outer layer is a longitudinal type of muscle Stomach Processes List and explain the function of the three substances present in the gastric juices. Pepsin – A protease which helps break down the protein component within the food or chime into smaller fragments called peptides. Pepsin works pretty well under the extreme acid conditions present in the stomach. Lipases – Start to digest smaller fats, especially dairy type fats which have smaller fatty acids. Glycoprotein – An important molecule because it bonds to the vitamin B12, and protects it from being broken down by the gastric juices. Without glycoprotein, you would not have active vitamin B12 in your system. Moving Through the Small Intestine Compare the pHs of the stomach to the small intestine. Goes from 2 in the stomach to above a level of 7 in the small intestine. Sodium Bicarbonate is also present to help neutralize the acidic chime coming from the stomach. Digesting Carbohydrates What are the simplest units that carbohydrates are broken into? Monosaccharides What makes enzymes so efficient? Body does not have to keep making new molecules for each enzyme. Digesting Fats What is the problem that we face with fat digestion in the small intestine and how is it solved? Fat is not soluble in water/small intestine is an aqueous environment. It is solved due to the fact that bile emulsifies the fat which allows it to be digested in the aqueous environment. How does fat travel? Travel in threes (triglycerides which are composed of fatty acids and glycerol) It is eventually broken up by lipase. Digesting Proteins What three protease enzymes help break down the molecules into amino acid fragments? Trypsin, Chymotrypsin, Carboxypeptidase Large Intestine Absorbing Nutrients How do the folds in the small intestine aid in absorption? They increase the surface area of the intestinal lining (increases the efficiency of the intestine). Define villi. They are fingerlike projections that increase the surface area of the intestine even further (help entrap small particles of food to help further digest it). Regulating Digestion Which hormone is secreted by the intestine that signals the pancreas to secrete sodium bicarbonate? Secretin
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