The Digestive System

Digestion Gastrointestinal (GI) tract (Alimentary canal) Digestive system is responsible for the physical and chemical breakdown of food so it can be taken into the bloodstream and used by body cells and tissues Gastrointestinal (GI) tract (Alimentary canal) Mouth Oral Cavity Pharynx Esophagus Stomach Duodenum Jejunum Ileum Cecum Ascending colon Transverse colon Anus 1

Mouth Receives food as it enters the body Actions in the mouth food is tasted broken down physically by the teeth lubricated and partially digested by saliva swallowed

Mouth Teeth special structures in the mouth break down food physically by chewing and grinding the food, a process called mastication

Mouth Tongue 2 muscular organ contains special receptors that taste sweet, salt, sour, and bitter also aids in chewing and swallowing of food 2

Mouth Hard Palate 21 bony structure that forms the roof of the mouth separates the mouth from the nasal cavities 21

Mouth Soft Palate Uvula located behind the hard palate separates the mouth from the nasopharynx Uvula helps prevent food from entering the nasopharynx during swallowing 16

Mouth Salivary glands 22 23 three pairs of glands parotid, sublingual, and submandibular produce liquid called saliva lubricates the mouth during speech an chewing moistens food so it can be swallowed contains enzymes called salivary amylase speeds up chemical reaction begins the breakdown of carbohydrates into sugars 22 23

Pharynx After the food is chewed and mixed with saliva, it is called a bolus and it enters the pharynx or throat Tube that carries both air and food Carries the air to the trachea Carries the food to the esophagus when bolus is swallowed, muscle action causes the epiglottis to close over the larynx prevents bolus from entering the respiratory tract (trachea) in this way, the bolus enters the esophagus 3 4

Esophagus Muscular tube dorsal to the trachea receives bolus from the pharynx and carries it to the stomach relies on a rhythmic, wavelike involuntary movement of its muscles, called peristalsis, to move the food in a forward direction

Peristalsis

Stomach Enlarged part of the alimentary canal Receives the food from the esophagus Mucous membrane lining contains folds called rugae, which disappear as the stomach fills with food and expands Cardiac sphincter circular muscle between the esophagus and the stomach closes after food enters the stomach prevents food from going back up into the esophagus 24

Stomach Pyloric sphincter circular muscle between the stomach and stomach intestine keeps food in the stomach until it is ready to enter the small intestine food usually remains in the stomach for about one to four hours 25

Stomach Gastric juices 5 26 produced by glands in the stomach convert food into a semifluid material called chyme juices contain hydrochloric acid lipase, which begins the chemical breakdown of fats pepsin, which starts protein digestion in an infant, enzyme rennin is secreted aids in digestion of milk not present in adults 5 26

Small Intestine Coiled section of the alimentary canal about 20 feet long and 1 inch in diameter Where most of digestion takes place Three sections duodenum first 9 to 10 inches bile from the gallbladder and liver and pancreatic juice from the pancreas enter this section through ducts or tubes jejunum about 8 feet long and forms the middle section ileum final 12 feet connects with the large intestine at the cecum circular muscle called the ileocecal valve separates the ileum and cecum and prevents food from returning to the ileum 6

Small Intestine

Small Intestine 32 Completes the process of digestion Absorbs the products of digestion into the blood stream for use by body cells. Intestinal juices produced by the small intestine contain the enzymes maltase, sucrase, and lactase, which break down sugars into simpler forms contain enzymes known as peptidases, which complete the digestion of proteins contain the enzyme steapsin, which aids in the digestion fat Bile liquid that enters small intestine from liver and gallbladder emulsifies or physically breaks down fats 32

Small Intestine Pancreatic juice 29 liquid that enters small intestine from liver and gallbladder contains enzymes that complete the process of digestion pancreatic amylase or amylopsin, which acts on sugars trypsin and chymotrypsin, which act on proteins lipase or steapsin, which acts on fats 29

Small Intestine Villi fingerlike projections that line wall of small intestine allow food to be absorbed or taken into bloodstream contain blood capillaries and lacteals blood capillaries absorb the digested nutrients and carry them to the liver where they are stored or released into general circulation for use by body cells lacteals pick up most of the digested fats and carry them to the thoracic duct in the lymphatic system, which releases them into the circulatory system 7 28

Large Intestine Final section of the alimentary canal About 5 feet long and about 2 inches in diameter Functions absorption of water and any remaining nutrients storage of indigestible materials before they are eliminated from the body synthesis and absorption of some B-complex vitamins and vitamin K by bacteria present in intestine transportation of the waste products out of the alimentary canal 31

Large Intestine 8 11 27 Cecum Colon Rectum first section connects with the ileum of the small intestine contains a small projection called the vermiform appendix Colon ascending colon continues up the right side of the body from the cecum to the lower part of the liver transverse colon extends across the abdomen, below the liver and stomach, but above the small intestine descending colon extends down the left side of the body sigmoid colon connects with descending colon, is S-shaped and joins with the rectum Rectum final 6 to 8 inches storage area for the indigestibles or wastes fecal material or stool, the final waste product of the digestive process, is expelled through the anus 8 11 27

Large Intestine

Liver Largest gland in the body Accessory organ for the digestive tract Located under the diaphragm in the upper right quadrant of the abdomen 9

Liver Functions secretes bile used to emulsify or physically break up fats also makes fats water soluble for absorption stores sugar glycogen is converted to glucose released into the bloodstream when additional sugar is needed stores iron and certain vitamins produces heparin to prevent clotting produces blood proteins (fibrinogen/prothrombin) to help clotting produces cholesterol detoxifies substances such as alcohol and pesticides and detoxifies bacteria in blood from the intestine

Liver

Gallbladder 10 Small muscular sac Located under the liver and attached to it by connective tissue Stores and concentrates bile, which it receives from the liver When the bile is needed in the digestive tract to emulsify fats, it contracts and pushes the bile through the common bile duct into the duodenum 10

Gallbladder

Pancreas Fish-shaped organ located behind the stomach Produces pancreatic juices juices enter the duodenum through pancreatic duct contain enzymes to digest food amylase or amylopsin for sugars trypsin and chymotrypsin for proteins lipase or steapsin for fats Produces insulin secreted into blood stream regulates metabolism or burning of carbohydrates to convert glucose (blood sugar) to energy 30

Pancreas

Diseases and abnormal conditions Appendicitis acute inflammation of the appendix usually caused by an obstruction and infection generalized abdominal pain that later localizes at the lower right quandrant nausea and vomiting fever elevated WBC count if appendix ruptures, infectious material spills out into peritoneal cavity and causes peritonitis, a serious problem 18

Diseases and abnormal conditions Cholecystitis inflammation of the gallbladder cholelithiasis: gallstones form from crystallized cholesterol, bile salts, and bile pigments symptoms frequently occur after eating fatty foods indigestion, nausea and vomiting pain under the rib that radiates to the right shoulder if gallstone blocks bile duct, gallbladder can rupture and cause peritonitis treatment includes low fat diets; lithotripsy (shock waves); cholecystectomy 34

Diseases and abnormal conditions Cirrhosis chronic destruction of liver cells accompanied by the formation of fibrous connective and scar tissue causes: malnutrition associated w/alcoholism, hepatitis, bile duct disease, and chemical toxins symptoms vary and become more severe hepatomegaly anemia and nosebleeds indigestion, nausea, and vomiting jaundice ascites or an accumulation of fluid in abdominal peritoneal cavity when liver fails, disorientation, hallucinations, hepatic coma, and death can occur treatment directed toward preventing further damage avoiding alcohol and preventing infections proper nutrition and vitamin supplementation rest and appropriate exercise 33

Diseases and abnormal conditions Constipation condition that occurs when fecal material remains in the colon too long, causing excessive reabsorption of water feces or stool becomes hard, dry and difficult to eliminate causes: poor bowel habits, chronic use of laxatives, causing lazy bowels, diets low in fiber, and certain digestive diseases usually corrected by a diet high in fiber, adequate fluids and exercise at times, laxatives used to stimulate defecation frequent use can be habit forming 19

Diseases and abnormal conditions Diarrhea condition characterized by frequent watery stools causes: infections, stress, diet, an irritated colon, and toxic substances extremely dangerous in infants and small children due to the excessive fluid loss treatment eliminate cause provide adequate fluid intake modify the diet

Diseases and abnormal conditions Diverticulitis inflammation of diverticula, pouches or sacs that form in the intestine as the mucosal lining pushes through the surrounding muscle when fecal material and bacteria become trapped in diverticula, inflammation occurs can cause an abscess or rupture leading to peritonitis symptoms vary depending on the amount of inflammation abdominal pain; irregular bowel movements; flatus; constipation; diarrhea; abdominal distention; fever; nausea; vomiting treatment can include antibiotics, stool softener, pain medication and surgery. 12

Diseases and abnormal conditions Gastroenteritis inflammation of mucous membrane lining the stomach and intestinal tract food poisoning, infections, and toxins symptoms abdominal cramping nausea and vomiting fever diarrhea treatment usually rest and increased fluid intake antibiotics, intravenous fluids, and medications to slow peristalsis

Diseases and abnormal conditions Hemorrhoids painful, dilated or varicose veins of rectum and/or anus caused by straining to defecate or constipation pressure during pregnancy insufficient fluid intake abuse of laxatives prolonged sitting or standing symptoms include pain, itching and bleeding treatment high fiber diet with increased fluid intake stool softeners sitz baths or warm moist compresses hemorrhoidectomy

Diseases and abnormal conditions Hepatitis viral inflammation of the liver type A (HAV) or infectious hepatitis highly contagious transmitted in food or water that has been contaminated by the feces of an infected person vaccine is available type B (HBV) or serum hepatitis transmitted by blood and serum more serious than type A and can lead to chronic hepatitis or cirrhosis hepatitis B vaccine recommended for all health workers other strains in C, D, and E symptoms include fever, anorexia, nausea, vomiting, fatigue, dark urine, clay colored stool, enlarged liver and jaundice treatment rest diet high in protein and calories and low in fat liver transplant if necessary 13 20

Diseases and abnormal conditions Hernia occurs when an internal organ pushes through a weakened area or natural opening in a body wall hiatal hernia stomach protrudes through the diaphragm into the chest cavity symptoms: heartburn, distention of the stomach, chest pain, dysphagia treatment: bland diet, small, frequent meals, not lying down after meals, and surgical repair inguinal hernia section of the small intestine protrudes through the inguinal rings of the lower abdominal wall (indirect) protrudes directly through abdominal muscle (direct) if hernia cannot be pushed back in place, a herniorrhapy is done. 14

Diseases and abnormal conditions Pancreatitis inflammation of the pancreas in which pancreatic enzymes begin to digest the pancreas pancreas becomes necrotic, inflamed and edematous if damage extends to blood vessels in the pancreas, hemorrhage and shock occur causes excessive alcohol consumption blockage of ducts by gallstones idiopathic origins 17

Diseases and abnormal conditions Pancreatitis symptoms include severe abdominal pain that radiates to the back, nausea, vomiting, diaphoresis and jaundice if swelling blocks the common bile duct treatment cholecystectomy analgesics nutritional support pancreatitis caused by alcoholism has a poor prognosis and often results in death

Diseases and abnormal conditions Peritonitis inflammation of the abdominal peritoneal cavity usually occurs when a rupture in the intestine allows fecal contents to enter this cavity ruptured appendix or gallbladder are causes symptoms include abdominal pain distention fever nausea vomiting 18

Diseases and abnormal conditions Ulcer open sore on the lining of the digestive tract peptic ulcers include gastric and duodenal Heliobacter pylori bacterium that burrow into stomach membranes allows stomach acids and digestive juices to create and ulcer symptoms: burning pain, indigestion, hematemesis and melena treatment antacids and bland diet decreasing stress avoiding irritants (alcohol, fried foods, tobacco, caffeine) antibiotics if H. pylori is present and a bismuth prep surgery 15 35

Diseases and abnormal conditions Ulcerative colitis severe inflammation of the colon with the formation of ulcers and abscesses thought to be caused by stress, allergic reactions to food, or an autoimmune reaction symptoms diarrhea w/blood, pus, and mucous weight loss, weakness, abdominal pain, anemia periods of remission and exacerbation are common treatment control inflammation reduce stress, proper nutrition, avoid aggravation foods surgical removal of affected colon or colostomy