Chapter 3 Digestion From Meals to Molecules Chapter 3 Learning Define the following terms digestion absorption mucus Objectives 1 2 3 4 5 6 hormones enzymes epiglottis Identify the organ systems that assist with digestion and absorption of nutrients and those that assist with the elimination of metabolic waste products List the organs that make up the digestive system including the accessory organs Describe how each of the organs involved with the digestion system assists with digestion and absorption List the 3 sphincters associated with the gastrointestinal tract GIT discussed in this lecture and describe where they are located Distinguish between mechanical digestion and chemical digestion Copyright 2010 John Wiley Sons Inc Chapter 3 Learning Explain the roles of saliva mucus enzymes bicarbonate Objectives hormones and hydrochloric acid in digestion 7 8 9 10 11 12 13 Identify the enzyme or group of enzymes responsible for digestion of the macronutrients Explain how the structure of the lumen of the small intestine aids in the function of the small intestine Outline the process of digestion and absorption from the mouth to the anus Discuss the methods of the absorption of nutrients from the small intestine Describe the role of the cardiovascular system and lymphatic system in distributing nutrients and oxygen to the cells in the body and in the elimination of waste Explain how the GIT protects us from infection Copyright 2010 John Wiley Sons Inc Chapter 3 Learning Objectives Discuss the role of the microflora gut flora in maintaining 13 14 15 16 17 18 19 20 21 health including their function in metabolism of nutrients Define prebiotics and probiotics Describe the causes of food allergies Describe celiac disease Identify food groups that those with celiac disease may consume and food groups that need to be avoided Define GERD why it occurs and identify complications associated with it if left untreated Define peptic ulcer and discuss its major cause Describe diarrhea constipation and diverticula Identify primary causes for constipation and diarrhea Copyright 2010 John Wiley Sons Inc Organs and organ systems Definitions Organ Organ system A structure that is made up of more than one tissue that performs a specialized function A group of organs that work together to perform a specific task Multiple organ systems in the body Copyright 2010 John Wiley Sons Inc Organ systems 2012 John Wiley Sons Inc All rights reserved Organ systems 2012 John Wiley Sons Inc All rights reserved Organ systems 2012 John Wiley Sons Inc All rights reserved Organ systems 2012 John Wiley Sons Inc All rights reserved Digestion vs absorption What is the definition of digestion What is the difference between mechanical digestion and chemical digestion What is the definition of absorption Which comes first Digestive system secretions chemical digestion Mucus is secreted from mucosal cells lining the digestive tract Enzymes speed up reactions moistens lubricates and protects the digestive system for digestion help breakdown larger molecules into smaller ones Hormones chemicals secreted from cells which travel through the bloodstream to signal cells in another part of the body 2012 John Wiley Sons Inc All rights reserved Digestive enzymes 2012 John Wiley Sons Inc All rights reserved Digestion in the Mouth Mechanical and chemical digestion begins Saliva Teeth detect food chemicals Tongue break down food particles Taste buds secreted from salivary glands after the sight smell or presence of food Contains lubricants enzymes and other substances helps mix food and aids chewing Bolus formed 2012 John Wiley Sons Inc All rights reserved Pharnyx Part of digestive and respiratory systems Epiglottis blocks food from entering the trachea windpipe and lungs during swallowing 2012 John Wiley Sons Inc All rights reserved The esophagus to the Peristalsis stomach Lower esophageal sphincter Copyright 2010 John Wiley Sons Inc The Stomach Pyloric Sphincter Thought smell sight of food starts gastric motility and increase gastric secretions Food enters stomach stimulates release Gastrin Increases secretion of gastric juices Stomach Temporary storage of food Stomach lining produces gastric juice containing Water Pepsinogen activated into the digestive enzyme pepsin Digestive enzyme for protein precursor Hydrochloric acid Kills micro organism Unfolds proteins activates pepsin Inhibits amylase Mucus 2012 John Wiley Sons Inc All rights reserved Stomach Churning of stomach muscles to mix food Little absorption water alcohol aspirin acetaminophen Tylenol are absorbed End result chyme leaves the stomach to enter the small intestine through a sphincter Stomach emptying is regulated by signals from the small intestines and is affected by meal size and composition 2012 John Wiley Sons Inc All rights reserved Food enters small intestine stretches it decrease stomach motility decrease gastric juice secretion The Small Intestine Narrow tube that is approximately 20 ft long Main site for digestion absorption Divided into three segments Duodenum Jejunum Ileum Copyright 2010 John Wiley Sons Inc Structure of the Small Intestine Copyright 2010 John Wiley Sons Inc Small intestines Chyme moved by peristalsis and mixed by rhythmic constrictions called segmentation Undigested substances pass from the small intestines to the large intestines through a sphincter ileocecal sphincter 2012 John Wiley Sons Inc All rights reserved Accessory organs involved in digestion in SI http www webmd com digestive disorders picture of the gallbladder Copyright 2010 John Wiley Sons Inc Small intestine secretions Pancreas secretes pancreatic juice containing Bicarbonate neutralizes stomach acid Pancreatic amylase carbohydrates Pancreatic proteases proteins Pancreatic lipases fats Brush border secretes digestive enzymes for carbohydrates proteins 2012 John Wiley Sons Inc All rights reserved Small intestine secretions Pancreatic sections cont Liver produces and secretes bile emulsifies fat breaks up droplets so lipases can access molecules Gall bladder stores bile Small intestines chemical digestion 2012 John Wiley Sons Inc All rights reserved Transport across membranes Diffusion movement of substances from areas of higher concentration to areas of lower concentration Simple diffusion diffusion across membranes Facilitated diffusion diffusion through a membrane protein Osmosis diffusion of water across membranes Active transport movement of substances across membranes