Digestive System Processes

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DIGESTIVE SYSTEM DIGESTIVE SYSTEM Objectives: - Identify the organs of the digestive system and list their major functions. (stomach, small intestine, large intestine and salivary glands, pancreas, liver, gall bladder) - Explain the processes by which materials move through the digestive tract. - Outline the mechanisms that regulate digestion. The digestive system consists of a muscular tube, the digestive tract, also called the gastrointestinal tract (GI) or alimentary canal, and various accessory organs. The nutrition for the cells of the body must be in a simple The nutrition for the cells of the body must be in a simple form: amino acids, simple sugars, and fatty acids. form: amino acids, simple sugars, and fatty acids. The digestion process: The digestion process: The digestive system takes the The digestive system takes the complex organic molecules of the foods we ingest — complex organic molecules of the foods we ingest — proteins, carbohydrates, and fats — and break them down proteins, carbohydrates, and fats — and break them down into their simple form. The simple molecules (nutrients) are into their simple form. The simple molecules (nutrients) are absorbed from the digestive system by the cardiovascular absorbed from the digestive system by the cardiovascular and lymphatic systems and transported to cells throughout and lymphatic systems and transported to cells throughout the body. the body. The digestive system may The digestive system may divide into two parts: divide into two parts: - A muscular tube, known - A muscular tube, known as the alimentary canal or as the alimentary canal or digestive tract: the mouth, digestive tract: the mouth, pharynx, esophagus, pharynx, esophagus, stomach, small intestine, and stomach, small intestine, and large intestine. large intestine. - The accessory digestive - The accessory digestive organs and glands that help organs and glands that help in the digestive process in the digestive process include the tongue, teeth, include the tongue, teeth, salivary glands, pancreas, salivary glands, pancreas, liver, and gall bladder. liver, and gall bladder. Functions of the Digestive System : - Ingestion occurs when materials enter the digestive tract via the mouth. Ingestion is an active process involving conscious choice and decision making. - Mechanical processing is crushing and shearing that makes materials easier to propel along the digestive tract. It also increases their surface area, making them more susceptible to enzymatic attack. - Digestion refers to the chemical breakdown of food into small organic fragments suitable for absorption by the digestive epithelium. Simple molecules in food, such as glucose, can be absorbed intact, but epithelial cells cannot to absorb molecules the size and complexity of proteins, polysaccharides, or triglycerides. These molecules must be splitted by digestive enzymes prior to absorption. - Secretion is the release of water, acids, enzymes, buffers, and salts by the epithelium of the digestive tract and by glandular organs. - Absorption is the movement of organic substrates, electrolytes (inorganic ions), vitamins, and water across the digestive epithelium and into the interstitial fluid of the digestive tract. - Excretion is the removal of waste products from body fluids. Peristalsis : - The muscularis externa propels materials from one portion of the Digestive System Processes Digestive System Processes Bởi: OpenStaxCollege Obtaining nutrition and energy from food is a multi-step process For true animals, the first step is ingestion, the act of taking in food This is followed by digestion, absorption, and elimination In the following sections, each of these steps will be discussed in detail Ingestion The large molecules found in intact food cannot pass through the cell membranes Food needs to be broken into smaller particles so that animals can harness the nutrients and organic molecules The first step in this process is ingestion Ingestion is the process of taking in food through the mouth In vertebrates, the teeth, saliva, and tongue play important roles in mastication (preparing the food into bolus) While the food is being mechanically broken down, the enzymes in saliva begin to chemically process the food as well The combined action of these processes modifies the food from large particles to a soft mass that can be swallowed and can travel the length of the esophagus Digestion and Absorption Digestion is the mechanical and chemical break down of food into small organic fragments It is important to break down macromolecules into smaller fragments that are of suitable size for absorption across the digestive epithelium Large, complex molecules of proteins, polysaccharides, and lipids must be reduced to simpler particles such as simple sugar before they can be absorbed by the digestive epithelial cells Different organs play specific roles in the digestive process The animal diet needs carbohydrates, protein, and fat, as well as vitamins and inorganic components for nutritional balance How each of these components is digested is discussed in the following sections Carbohydrates The digestion of carbohydrates begins in the mouth The salivary enzyme amylase begins the breakdown of food starches into maltose, a disaccharide As the bolus of food travels through the esophagus to the stomach, no significant digestion of carbohydrates takes place The esophagus produces no digestive enzymes but does produce mucous 1/9 Digestive System Processes for lubrication The acidic environment in the stomach stops the action of the amylase enzyme The next step of carbohydrate digestion takes place in the duodenum Recall that the chyme from the stomach enters the duodenum and mixes with the digestive secretion from the pancreas, liver, and gallbladder Pancreatic juices also contain amylase, which continues the breakdown of starch and glycogen into maltose, a disaccharide The disaccharides are broken down into monosaccharides by enzymes called maltases, sucrases, and lactases, which are also present in the brush border of the small intestinal wall Maltase breaks down maltose into glucose Other disaccharides, such as sucrose and lactose are broken down by sucrase and lactase, respectively Sucrase breaks down sucrose (or “table sugar”) into glucose and fructose, and lactase breaks down lactose (or “milk sugar”) into glucose and galactose The monosaccharides (glucose) thus produced are absorbed and then can be used in metabolic pathways to harness energy The monosaccharides are transported across the intestinal epithelium into the bloodstream to be transported to the different cells in the body The steps in carbohydrate digestion are summarized in [link] and [link] Digestion of carbohydrates is performed by several enzymes Starch and glycogen are broken down into glucose by amylase and maltase Sucrose (table sugar) and lactose (milk sugar) are broken down by sucrase and lactase, respectively Digestion of Carbohydrates Enzyme Produced By Site of Action Substrate Acting On Salivary amylase Salivary glands Mouth Disaccharides Polysaccharides (maltose), (Starch) oligosaccharides Pancreatic amylase Pancreas Oligosaccharidases Lining of the intestine; brush End Products Disaccharides Small Polysaccharides (maltose), intestine (starch) monosaccharides Small Disaccharides intestine Monosaccharides (e.g., glucose, 2/9 Digestive System Processes Digestion of Carbohydrates Enzyme Produced By border membrane Site of Action Substrate Acting On End Products fructose, galactose) Protein A large part of protein digestion takes place in the stomach The enzyme pepsin plays an important role in the digestion of proteins by breaking down the intact protein to peptides, which are short chains of four to nine amino acids In the duodenum, other enzymes—trypsin, elastase, and chymotrypsin—act on the peptides reducing them to smaller peptides Trypsin elastase, carboxypeptidase, and chymotrypsin are produced by the pancreas and released into the duodenum where they act on the chyme Further breakdown of peptides to single amino acids is aided by enzymes called peptidases (those that break down peptides) Specifically, carboxypeptidase, dipeptidase, and aminopeptidase play important roles in reducing the peptides to free amino acids The amino acids are absorbed into the bloodstream through the small ... System Processes and Memory Management Objectives Upon completion of this module, you should be able to: • Identify processes on your system using the ps command • Find a process using the pgrep command • Control processes using the jobs command • Terminate unwanted processes using the kill and pkill commands Discussion – At times an application that you are running will freeze or cause your system to become inaccessible. How would you regain control of your workstation? System Process Overview Each task you perform in the Linux environment starts a process. An example of a process is using vi to edit a letter, or sending a file to the printer. Each process is assigned a unique process identification number (PID), which is used by the system to identify the process. The following pages define useful commands on how to locate a process and terminate processes. Process Hierarchy There are five types of processes on a Linux system: • Daemon • Parent • Child • Orphan • Zombie or defunct Daemon processes are processes that are started by the kernel and exist for a specific purpose. For instance, the lpd daemon exists for the sole purpose of handling print jobs. When no printing is taking place on the system, the lpd daemon is running but inactive. When a print job is submitted, this daemon becomes active until the job is finished. The login daemon provides the CDE login screen at the beginning of a user’s session and again after the user exits CDE. Following system boot-up, a process called init is invoked. This process is at the top of the process hierarchy and is responsible for spawning many system processes. The login daemon is spawned by init and init is, therefore, referred to as the parent process of the login daemon. When a user is working in a terminal window in CDE, that terminal’s PID is the parent process ID (PPID) of any commands issued in the terminal. These commands are child processes of the terminal process. The parent process receives and displays the output from the child process and then “kills” the process. If a command is issued in a terminal window and the window is closed before the command returns output, that process becomes an orphan. The system passes the orphan process to init which then becomes the parent process and terminates the child process. Occasionally a child process does not return to the parent process with its output. This process becomes “lost” in the system. The only resource this process uses is a slot in the process table; it cannot be stopped in a conventional manner. This type of process is called a zombie or defunct process. The only way to kill a defunct process is to reboot the system. Processes and PIDs Use the ps command to list the processes currently running on the system. The output of this command will display the PID number and the command associated with it. Many times a PID number is needed for use with the kill command . Command Format ps [-options] Options -e Print information about every process on the system. -f Generate a full listing. (Refer to the man pages for a description of the headings displayed.) Because of the number of processes usually running on a system, it is useful to pipe the ps -ef command to more so that the output can be read a page at a time, as in the example on the next page. Displaying a Full Listing of All Processes $ ps -ef | more UID PID PPID C STIME TTY TIME CMD root 0 0 80 16:46:41 ? 0:01 sched root 1 0 80 16:46:44 ? 0:40 /etc/init - root 2 0 27 16:46:44 ? 0:00 pageout root 3 0 80 16:46:44 ? 4:33 fsflush root 236 1 80 16:48:08 ? 0:01 /usr/lib/saf/sac root 844 1 54 12:12:10 ? 0:00 /usr/lib/lpsched aster 1292 1 80 06:48:51 console 0:01 -ksh root 241 236 69 16:48:14 ? 0:01 /usr/lib/saf/ttymon rose GEOCHEMISTRY – EARTH'S SYSTEM PROCESSES Edited by Dionisios Panagiotaras Geochemistry – Earth's System Processes Edited by Dionisios Panagiotaras Published by InTech Janeza Trdine 9, 51000 Rijeka, Croatia Copyright © 2012 InTech All chapters are Open Access distributed under the Creative Commons Attribution 3.0 license, which allows users to download, copy and build upon published articles even for commercial purposes, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. 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Publishing Process Manager Mia Macek Technical Editor Teodora Smiljanic Cover Designer InTech Design Team First published April, 2012 Printed in Croatia A free online edition of this book is available at www.intechopen.com Additional hard copies can be obtained from orders@intechopen.com Geochemistry – Earth's System Processes, Edited by Dionisios Panagiotaras p. cm. ISBN 978-953-51-0586-2 Contents Preface IX Chapter 1 Geochemical and Sedimentation History of Neogene Lacustrine Sediments from the Valjevo-Mionica Basin (Serbia) 1 Aleksandra Šajnović, Ksenija Stojanović, Vladimir Simić and Branimir Jovančićević Chapter 2 Arsenic Geochemistry in Groundwater System 27 Dionisios Panagiotaras, George Panagopoulos, Dimitrios Papoulis and Pavlos Avramidis Chapter 3 Geochemistry of Hydrothermal Alteration in Volcanic Rocks 39 Silvina Marfil and Pedro Maiza Chapter 4 Estimated Background Values of Some Harmful Metals in Stream Sediments of Santiago Island (Cape Verde) 61 Marina M. S. Cabral Pinto, Eduardo A. Ferreira da Silva, Maria M. V. G. Silva and Paulo Melo-Gonçalves Chapter 5 The Relevance of Geochemical Tools to Monitor Deep Geological CO 2 Storage Sites 81 Jeandel Elodie and Sarda Philippe Chapter 6 Sm-Nd and Lu-Hf Isotope Geochemistry of the Himalayan High- and Ultrahigh-Pressure Eclogites, Kaghan Valley, Pakistan 105 Hafiz Ur Rehman, Katsura Kobayashi, Tatsuki Tsujimori, Tsutomu Ota, Eizo Nakamura, Hiroshi Yamamoto, Yoshiyuki Kaneko and Tahseenullah Khan Chapter 7 Geochemistry and Metallogenic Model of Carlin-Type Gold Deposits in Southwest Guizhou Province, China 127 Yong Xia, Wenchao Su, Xingchun Zhang and Janzhong Liu VI Contents Chapter 8 Behaviors of Mantle Fluid During Mineralizing Processes 157 Liu Xianfan, Li Chunhui, Zhao Fufeng, Tao Zhuan, Lu Qiuxia and Song Xiangfeng Chapter 9 Trace Metals Digestive System Digestion • Phases Include Ingestion Movement Mechanical and Chemical Digestion Absorption Elimination Digestion • Types – Mechanical (physical) • Chew • Tear • Grind • Mash • Mix – Chemical • Enzymatic reactions to improve digestion of – Carbohydrates – Proteins – Lipids Digestive System Organization • Gastrointestinal (Gl) tract – – – Tube within a tube Direct link/path between organs Structures • • • • • • • Mouth Pharynx Esophagus Stomach Small intestine Large Intestine Rectum Mouth • Teeth mechanically break down food into small pieces Tongue mixes food with saliva (contains amylase, which helps break down starch) • Epiglottis is a flap-like structure at the back of the throat that closes over the trachea preventing food from entering it It is located in the Pharynx Esophagus • Approximately 20 cm long • Functions include: Secrete mucus Moves food from the throat to the stomach using muscle movement called peristalsis • If acid from the stomach gets in here that’s heartburn Mouth, Pharynx and Esophagus Video Stomach • J-shaped muscular bag that stores the food you eat, breaks it down into tiny pieces • Mixes food with Digestive Juices that contain enzymes to break down Proteins and Lipids Lipids • Acid (HCl) in the stomach Kills Bacteria • Food found in the stomach is called Chyme Small Intestine • Small intestines are roughly meters long • Lining of intestine walls has finger-like projections called villi, to increase surface area • The villi are covered in microvilli which further increases surface area for absorption Crash Course Review Small Intestine • Nutrients from the food pass into the bloodstream through the small intestine walls • Absorbs: – 80% ingested water – Vitamins – Minerals – Carbohydrates – Proteins – Lipids • Secretes digestive enzymes Large Intestine • About 1.5 meters long • Accepts what small intestines don’t absorb • Rectum (short term storage which holds feces before it is expelled) • Functions Large Intestine – Bacterial digestion • Ferment carbohydrates Absorbs more water – Concentrate wastes – Accessory Organs The Glands • Not part of the path of food, but play a critical role • Include: Liver, gall bladder, and pancreas Liver • Directly affects digestion by producing bile – Bile helps digest fat • filters out toxins and waste including drugs and alcohol and poisons 13 Gall Bladder • Stores bile from the liver, releases it into the small intestine • Fatty diets can cause gallstones Pancreas • Produces digestive enzymes to digest fats, carbohydrates and proteins • Regulates blood sugar by producing insulin Web Page Reinforcement Video On a sheet of paper, write the name of each colored organ: • • • • • • • Green: Red: Pink: Brown: Purple: Green: Yellow: How’d you do? • • • • • • • Green: Esophagus Red: Stomach Pink: Small Intestine Brown: Large Intestine Purple: Liver Green: Gall Bladder Yellow: Pancreas Great Job! References and Links • Your Digestive System and How It Works – Digestive system diagram comes from this site • • • • The Real Deal on the Digestive System Pancreas: Introduction and Index Your Gross and Cool Body - Digestive System Laurentian Regional High School Data Base - you must know the Username and Password [...]... Large Intestine Purple: Liver Green: Gall Bladder Yellow: Pancreas Great Job! References and Links • Your Digestive System and How It Works – Digestive system diagram comes from this site • • • • The Real Deal on Physiology The Digestive System www.cambodiamed.com Functions of the GI Tract  Motility: • Movement of of food through the GI tract • Ingestion: • Taking food into the mouth • Mastication: • Chewing the food and mixing it with saliva • Deglutition: • Swallowing the food • Peristalsis: • Rhythmic wave-like contractions that move food through GI tract www.cambodiamed.com Functions of the GI Tract (continued) • Secretion: • Includes both exocrine and endocrine secretions • Exocrine: • HCl, H20, HC03-, bile, lipase, pepsin, amylase, trypsin, elastase, and histamine are secreted into the lumen of the GI tract • Endocrine: • Stomach and small intestine secrete hormones to help regulate the GI system • Gastrin, secretin, CCK, GIP, GLP-1, guanylin, VIP, and somatostatin www.cambodiamed.com Functions of the GI Tract (continued) • Digestion: • Breakdown of food particles into subunits (chemical structure change) • Absorption: • Process of the passage of digestion (chemical subunits) into the blood or lymph • Storage and elimination: • Temporary storage and elimination of indigestible food www.cambodiamed.com Digestive System (GI) • GI tract divided into: Insert fig 18.2 • Alimentary canal • Accessory digestive organs • GI tract is 30 ft long and extends from mouth to anus www.cambodiamed.com Layers of GI Tract • Composed of tunics: • Mucosa • Submucosa Muscularis Serosa  www.cambodiamed.com Mucosa • Lines the lumen of GI tract • Consists of simple columnar epithelium • Lamina propria: • Thin layer of connective tissue containing lymph nodules • Muscularis mucosae: • Thin layer of smooth muscle responsible for the folds • Folds increase surface area for absorption • Goblet cells: • Secrete mucus www.cambodiamed.com Submucosa • Thick, highly vascular layer of connective tissue • Absorbed molecules enter the blood and lymphatic vessels • Submucosal plexus (Meissner’s plexus): • Provide autonomic nerve supply to the muscularis mucosae www.cambodiamed.com Muscularis • Responsible for segmental contractions and peristaltic movement through the GI tract • Inner circular layer of smooth muscle • Outer longitudinal layer of smooth muscle • Contractions of these layers move food through the tract; pulverize and mix the food • Myenteric plexus located between the muscle layers • Major nerve supply to GI tract • Fibers and ganglia from both sympathetic and parasympathetic nervous systems www.cambodiamed.com Serosa • Binding and protective outer layer • Consists of areolar connective tissue covered with simple squamous epithelium www.cambodiamed.com Gastric Phase (continued) • Secretion of HCl is also regulated by a negative feedback effect: Insert Fig 18.30 • HCl secretion decreases if pH < 2.5 • At pH of 1.0, gastrin secretion ceases • D cells stimulate secretion of somatostatin • Paracrine regulator to inhibit secretion of gastrin www.cambodiamed.com Intestinal Phase • Inhibits gastric activity when chyme enters the small intestine • Arrival of chyme increases osmolality and distension • Activates sensory neurons of vagus and produces an inhibitory neural reflex: • Inhibits gastric motility and secretion • In the presence of fat, enterogasterone inhibits gastric motility and secretion • Hormone secretion: • Inhibit gastric activity: • Somatostatin, CCK, and GLP-1 www.cambodiamed.com Enteric Nervous System • Submucosal and myenteric plexuses contain 100 million neurons • Include preganglionic parasympathetic axons, ganglion cell bodies, postganglionic sympathetic axons; and afferent intrinsic and extrinsic sensory neurons www.cambodiamed.com Enteric Nervous System • Peristalsis: • ACh and substance P stimulate smooth muscle contraction above the bolus • NO, VIP, and ATP stimulate smooth muscle relaxation below the bolus (continued) Insert fig 18.31 www.cambodiamed.com Paracrine Regulators of the Intestine • Serotonin (5-HT): • Stimulates intrinsic afferents, which send impulses into intrinsic nervous system; and activates motor neurons • .. .Digestive System Processes for lubrication The acidic environment in the stomach stops the action of the... (starch) monosaccharides Small Disaccharides intestine Monosaccharides (e.g., glucose, 2/9 Digestive System Processes Digestion of Carbohydrates Enzyme Produced By border membrane Site of Action... small intestines The steps in protein digestion are summarized in [link] and [link] 3/9 Digestive System Processes Protein digestion is a multistep process that begins in the stomach and continues