C H A P T E R 11 Anatomy and Physiology of the Human Body

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Digestive System 10 U N I T

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Defining Digestion Digestion is the activity performed by the organs of the digestive system. Digestion is defined as the process by which food is broken down, mechanically and chemically, in the gastrointestinal tract into enzymes that are usable by the cells of the body.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The 4 Phases of the Digestive Process 1. Ingestion: taking in food and water 2. Digestion: breaks food down into nutrients 3. Absorption: enzymes used in the intestines 4. Elimination: urination or defecation of waste

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Raw Materials Required for a Healthy Body Carbohydrates provide energy. Proteins build and repair cells and tissue. Fats are a secondary energy source. Minerals (continued)

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Raw Materials Required for a Healthy Body Vitamins are chemicals needed for growth and to control bodily activities. Water regulates temperature, adds moisture to waste, and lubricates. Roughage speeds up the digestive process.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Pathway of Food through the Gastrointestinal (GI) Tract

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Structures of the Mouth Teeth  Break up food to make it easier to swallow and prepare it to become digestive enzymes Tongue  Moves food around within the mouth to bring it into contact with the teeth Salivary glands  3 glands that begin the chemical process of breaking down food

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Digestive Process That Occurs in the Mouth Teeth chop and grind down the food. The salivary glands secrete the enzyme ptyalin to break down carbohydrates into sugars. The saliva also cleans the teeth; the combination of mashed foods and saliva is called a bolus.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Process of Swallowing The bolus can go in three directions: 1. Up the nose 2. Down and forward into the trachea 3. Down into the esophagus The bolus raises the soft palate as it is swallowed and closes off the nasal cavity. (continued)

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Process of Swallowing The epiglottis moves across the opening to the larynx as the tongue pushes the bolus against the palate. At the moment of swallowing, the larynx moves upward against the epiglottis to close the opening off to the larynx. The bolus enters the esophagus.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved How the Esophagus Works Involuntary muscle action, called peristalsis, moves the bolus down the esophagus by alternately contracting and relaxing against the bolus. The bolus then moves down into the stomach.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Structure and Function of the Stomach The upper opening to the stomach is called the cardiac sphincter. This sphincter opens to allow the bolus to enter, and closes to prevent the bolus from going back up into the esophagus. (continued)

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Structure and Function of the Stomach The stomach is an organ made up of three layers of strong muscle tissue. The stomach has folds, called rugae, that allow it to expand as the bolus enters. The stomach begins to contract when the bolus enters and the bolus is mixed with gastric enzymes and hydrochloric acid as the chemical process of breaking down food continues. (continued)

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Structure and Function of the Stomach The bolus of partially digested food is changed into a semiliquid solution called chyme. When the consistency of the chyme is right, the pyloric sphincter muscle at the end of the stomach opens and allows the chyme to enter the small intestine.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Structure and Function of the Small Intestine The small intestine absorbs the nutrients from the chyme. At 20 feet in length, the small intestine has 3 sections: 1. Duodenum 2. Jejunum 3. Ileum

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Duodenum The duodenum receives the highest concentration of acids from the stomach. It is especially prone to the development of ulcers.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Functions of the Liver The largest gland in the body Secretes bile, which is required to digest fats Stores glycogen to be used when the body needs additional blood sugar. (continued)

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Functions of the Liver Processes proteins that burn fats as fuel or store fats Manufactures substances required for the process of clotting blood Produces antibodies to counteract certain disease organisms

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Portal Circulation Connection and the Liver The portal vein conveys absorbed nutrients and other substances from the abdominal organs for processing by the liver.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Role of the Gallbladder The sole purpose of the gallbladder is to concentrate and store bile to aid in the digestion of fats.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Association of the Gallbladder and the Liver The hepatic duct and the common bile duct, which branches off the gallbladder, must remain intact and functional for the liver to function.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Location and Function of the Pancreas The pancreas lies beneath the stomach with its head in the curve of the duodenum. The pancreas has 2 functions as a gland: 1. Exocrine gland: secretes pancreatic juices directly into the duodenum 2. Endocrine gland: secretes insulin directly into the bloodstream

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved How and Where Nutrients Are Absorbed Absorption occurs in the millions of villi that line the major part of the small intestine. The swinging motion of the villi keeps the chyme mixed with digestive juices. The external cells of the villi absorb nutrients, minerals, and water from the chyme. With useful nutrients and other substances absorbed from the chyme, waste enters the large intestine.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Sections of the Colon The large intestine is also called the colon. The ascending colon continues upward along the right side of the abdomen. The transverse colon extends in a loop across the abdominal cavity. The descending colon extends down the left side of the abdomen until it reaches the edge of the pelvic cavity.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Function of the Colon The large intestine absorbs excess liquid from the chyme. This water, plus some salts and proteins, are filtered out of the blood to be eliminated in urine. This waste forms feces to be eliminated through the rectum.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Function of the Rectum The rectum serves as a collecting area for feces, the remains of digestion.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Structure and Function of the Anal Canal The anal canal is a narrow passageway that extends from rectum to anus. This passageway is a voluntarily controlled muscle that is used to empty the rectum.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved The Structure and Function of the Anus The anus is the opening of the anal canal to the outside of the body.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Diagnostic Exams

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Colonoscopy An exam that uses a fiber optic scope to view the entire large intestine This exam requires patient preparation to clear the intestine of feces. This is indicated in patients with complaints of diarrhea, constipation, bleeding, or pain.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Gastrointestinal X-Rays Barium swallow  Uses a fluoroscope to view the action of the esophagus as the patient swallows a radiopaque liquid called barium Upper GI  After the barium swallow, additional barium is swallowed and the passage of the barium throughout the small intestine is observed. (continued)

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Gastrointestinal X-Rays Lower GI  The barium mixture is administered as an enema and outlines the structure of the large intestine.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Gastroscopy A fiber optic scope is used to view the esophagus, stomach, and upper duodenum. This procedure can also be used to remove small foreign objects that may be blocking the air passage.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Occult Blood Test This test is performed on feces to detect the presence of hidden blood in the stool.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Proctoscopy An examination of the lower rectum and anal canal; it’s preceded by a digital exam that evaluates the condition of the anal sphincter.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Sigmoidoscopy Uses a sigmoidoscope to view the lower portion of the sigmoid colon and the rectum This exam aids in the diagnosis of inflammation, infection, or ulcerative conditions.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Diseases and Disorders

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Anorectal Abscess and Fistula Anorectal abscesses  Painful, throbbing lumps that are a collection of exudate. Fistulas  The escape tracts that exudate may develop into the rectum.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Appendicitis and Cirrhosis Appendicitis  An acute inflammation of the appendix Cirrhosis  Chronic liver disease that causes destruction of liver cells; interferes with the life-preserving functions of the liver

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Colitis and Colostomy Colitis  Inflammation of the colon; causes tenderness and discomfort Colostomy  Surgical creation of an artificial opening of the colon, allowing fecal material to be excreted from the body through the abdominal wall

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Colorectal Cancer and Constipation Colorectal cancer  Malignancy of the colon or rectum Constipation  Sluggish bowel action that results in dry, hard, infrequent bowel movements

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Crohn’s Disease and Diarrhea Crohn’s disease  Inflammation of any portion of the GI tract Diarrhea  Repeated passage of unformed waste characterized by frequent, liquid stools

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Diverticulosis and Esophageal Varices Diverticulosis  Presence of bulging pouches in the walls of the GI tract where the lining has pushed into the surrounding muscle Esophageal varices  Dilated, tortuous veins in the lower section of the esophagus that result in fluids entering the abdominal cavity

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Anal Fissures and Gastroenteritis Anal fissures  Cracks or tears in the lining of the anus Gastroenteritis  Inflammation of the stomach and intestines that causes fever, nausea, abdominal cramping, diarrhea, and vomiting

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Gastroesophageal Reflux Disease and Hemorrhoids Gastroesophageal reflux disease (GERD)  Results from a backflow of gastric and sometimes duodenal contents into the esophagus through the sphincter just above the stomach Hemorrhoids  Veins in the folds of the anal canal become dilated, causing them to bulge or protrude outside the body

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Hepatitis Liver infection that can result in cell destruction and death  Type A  Transmitted through the fecal-oral route when waste organisms get into food  Type B  Transmitted through blood and sexual contact with an infected person

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Hernia Hernia: protrusion of an internal organ through a natural opening in the body wall  Hiatal hernia  A portion of the stomach slips through the diaphragmatic opening at the end of the esophagus  Inguinal hernia  Spermatic cords pass through the lower abdominal walls

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Ileostomy Surgical opening of the ileum to allow the chyme of the small intestine to empty through the abdominal wall

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Irritable Bowel Syndrome Chronic or periodic diarrhea and alternating constipation This condition is also called spastic colon.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Oral Cancer About 90% of oral cancers are squamous cell cancers that develop in the tissue linings of the mouth, lip, tongue, and throat. The use of snuff or tobacco, alcohol abuse, and overexposure to the sun are the primary risk factors for oral cancers.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Pancreatitis and Paralytic Ileus Pancreatitis  Chronic or acute inflammation of the pancreas  Enzymes that are normally produced and excreted into the pancreatic duct remain and digest pancreatic tissue Paralytic ileus  Physiological intestinal obstruction that usually occurs in the small intestine  Peristalsis is either dramatically reduced or totally absent.

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Peptic Ulcer Encircled lesions in the mucous membrane lining of the stomach, lower esophagus, duodenum, or jejunum

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Polyps and Pruritus Ani Polyps  Mass of tissue that results from an overgrowth of upper epithelial cells in the mucosal membrane of the GI tract Pruritus ani  Itching of the areas surrounding the anus; often associated with irritation and burning

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Pyloric Stenosis and Ulcerative Colitis Pyloric stenosis  A narrowing of the pyloric sphincter muscle; interferes with the emptying of the stomach Ulcerative colitis  An often chronic inflammatory disease that affects the mucosa of the colon, beginning in the sigmoid colon and extending upward into the whole colon

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Unit Summary List the organs, in order, of the GI tract through which food passes. Why is the duodenum vital to digestion?